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Acetaminophen and Salicylates (Systemic)

This monograph includes information on the following:

1) Acetaminophen and Aspirin 
2) Acetaminophen, Aspirin, and Salicylamide 
3) Acetaminophen and Salicylamide 


INN:
Acetaminophen— Paracetamol

VA CLASSIFICATION
Primary: CN103
Secondary: CN105; CN850

Commonly used brand name(s): Excedrin Extra-Strength Caplets1; Excedrin Extra-Strength Tablets1; Excedrin Migraine1; Gelpirin1; Goody's Fast Pain Relief1; Goody's Headache Powders1; Rid-A-Pain Compound3; Saleto2; Supac1; Vanquish Caplets1.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

Not commercially available in Canada.



Category:


Analgesic—

antimigraine—

antipyretic—

Indications

Accepted

Headache, migraine (treatment)—Acetaminophen, aspirin, and caffeine combination is indicated for the relief of mild to moderate pain associated with migraine headaches {40}.

Pain (treatment)
Pain, arthritic, mild (treatment) or
Fever (treatment)—Acetaminophen and salicylate combinations are indicated to relieve mild to moderate pain and reduce fever. Salicylamide is less effective than acetaminophen or aspirin. These medications provide only symptomatic relief; additional therapy to treat the cause of the pain or fever should be instituted when necessary.
—Acetaminophen and salicylate combinations are indicated to provide temporary relief of pain caused by mild inflammation or arthritis. Although acetaminophen may be effective in relieving pain caused by mild osteoarthritis, it has minimal anti-inflammatory activity. Salicylamide also has minimal anti-inflammatory activity. Therefore, efficacy in relieving pain caused by inflammation or arthritis may depend upon the quantity of aspirin present in the individual product.

Note: The Food and Drug Administration (FDA) has proposed that salicylamide be classified as a Category III ingredient (i.e., lacking documentation of efficacy) in OTC analgesic/antipyretic products. {04}


Unaccepted
Acetaminophen and salicylate combinations are not recommended for the treatment of severe inflammation or severe arthritic pain, or for long-term treatment of chronic arthritis. Achieving and maintaining therapeutically effective salicylate plasma concentrations may require ingestion of undesirably large daily doses of other ingredients present in these formulations. Also, prolonged high-dose administration of these combinations is not recommended because of the risk of analgesic nephropathy.


Pharmacology/Pharmacokinetics

Physicochemical characteristics:
Molecular weight—
    Acetaminophen: 151.16 {05}
    Aspirin: 180.16 {05}
    Salicylamide: 137.14 {05}
    Caffeine (anhydrous): 194.19 {05}

pKa—
    Aspirin: 3.5

Mechanism of action/Effect:


Analgesic:

Acetaminophen or

Salicylates: The mechanism of analgesic action has not been fully determined. Acetaminophen and salicylates may act by inhibiting prostaglandin synthesis in the central nervous system (CNS) and through a peripheral action by blocking pain-impulse generation. The peripheral action may also be due to inhibition of the synthesis of prostaglandins or to inhibition of the synthesis or actions of other substances that sensitize pain receptors to mechanical or chemical stimulation. Acetaminophen may act predominantly in the CNS, whereas salicylates may act predominantly via peripheral actions.

Caffeine: A mild CNS stimulant. Caffeine-induced constriction of cerebral blood vessels, which leads to a decrease in cerebral blood flow and in the oxygen tension of the brain, {06} may contribute to relief of some types of headache. Also, it has been suggested that the addition of caffeine to acetaminophen and/or aspirin may provide a more rapid onset of action and/or enhanced pain relief with lower doses of analgesics. The U.S. FDA has determined that studies have shown that caffeine is an effective adjuvant to aspirin, but that studies performed to date have failed to demonstrate that it is an effective adjuvant to acetaminophen. {07}



Antipyretic:

Acetaminophen and salicylates may produce antipyresis by acting centrally on the hypothalamic heat-regulating center to produce peripheral vasodilation, resulting in increased cutaneous blood flow, sweating, and heat loss. The central action may involve inhibition of prostaglandin synthesis in the hypothalamus. However, there is some evidence that salicylates may also act through other mechanisms to relieve fevers caused by endogenous pyrogens that do not act via a prostaglandin mechanism.



Other actions/effects:


Aspirin:

Also inhibits platelet aggregation.

Also has anti-inflammatory and antirheumatic actions; however, the required plasma concentrations may not be achievable with the quantities present in these combination medications. The exact mechanisms of anti-inflammatory activity have not been determined, but aspirin may act peripherally in inflamed tissue, probably by inhibiting the synthesis of prostaglandins and possibly by inhibiting the synthesis and/or actions of other mediators of the inflammatory response. Inhibition of leukocyte migration, inhibition of the release and/or actions of lysosomal enzymes, and actions on other cellular and immunological processes in mesenchymal and connective tissues may also be involved. Antirheumatic actions are effected via analgesic and anti-inflammatory mechanisms; the therapeutic effects are not due to pituitary-adrenal stimulation.

Large doses may decrease hepatic synthesis of procoagulant factors and prolong prothrombin time.


Absorption:


Following oral administration:

Acetaminophen: Rapid and almost complete; may be decreased if taken following a high-carbohydrate meal.

Salicylates: Generally rapid and complete but may vary according to specific salicylate used and other factors such as tablet dissolution rate and gastric or intraluminal pH. Food decreases the rate, but not the extent, of absorption.

Caffeine: Well absorbed from the gastrointestinal tract.


Distribution:


In breast milk:

Acetaminophen: Peak concentrations of 10 to 15 mcg per mL (66.2 to 99.3 micromoles/L) have been measured 1 to 2 hours following maternal ingestion of a single 650-mg dose.

Aspirin: As salicylate—Peak salicylate concentrations of 173 to 483 mcg per mL (17.3 to 48.3 mg per 100 mL; 960 to 2680 mmol/L) have been measured 5 to 8 hours after maternal ingestion of a single 650-mg dose.


Protein binding:

Acetaminophen—Not significant with usual analgesic doses.

Salicylate (from aspirin)—High (to albumin); decreases as plasma salicylate concentration increases, with reduced plasma albumin concentration or renal dysfunction, and during pregnancy. {08}

Salicylamide—Not extensively bound to plasma proteins.

Caffeine—Low.

Biotransformation:

Acetaminophen—Approximately 90 to 95% of a dose is metabolized in the liver, primarily by conjugation with glucuronic acid, sulfuric acid, and cysteine. An intermediate metabolite is hepatotoxic.

Aspirin—Largely hydrolyzed in the gastrointestinal tract, liver, and blood to salicylate, which is further metabolized, primarily in the liver.

Salicylamide—Not hydrolyzed to salicylate in vivo . Although it is chemically and pharmacologically related to the salicylates, it is not considered a true salicylate.

Caffeine—Hepatic.

Half-life:


Acetaminophen:

1 to 4 hours; does not change with renal failure but may be prolonged in some forms of hepatic disease, in overdose, in the elderly, and in the neonate; may be somewhat shortened in children.

In breast milk: 1.35 to 3.5 hours.



Aspirin:

15 to 20 minutes (for intact molecule); rapidly hydrolyzed to salicylate.

In breast milk (as salicylate): 3.8 to 12.5 hours (average, 7.1 hours) following a single 650-mg dose.



Salicylate (from aspirin):

Dependent on dose and urinary pH; about 2 to 3 hours with usual analgesic doses.



Caffeine:

3 to 4 hours.


Time to peak concentration:

Acetaminophen—0.5 to 2 hours.

Aspirin—Generally 1 to 2 hours with single doses.

Peak serum concentration

Acetaminophen—5 to 20 mcg per mL (33.1 to 132.4 micromoles/L), with doses up to 650 mg.

Therapeutic plasma concentration

Analgesic and antipyretic—Salicylate (from aspirin): 25 to 50 mcg per mL (2.5 to 5 mg per 100 mL [0.18 to 0.36 mmol/L]); these concentrations are generally reached with doses of 325 to 650 mg.

Time to peak effect

Acetaminophen—1 to 3 hours.

Duration of action:

Acetaminophen—3 to 4 hours.

Elimination:


Acetaminophen—
        Renal, as metabolites, primarily conjugates; 3% of a dose may be excreted unchanged.


In dialysis—
        Hemodialysis—120 mL per minute (for unmetabolized drug); metabolites also cleared rapidly.
        Hemoperfusion—200 mL per minute.
        Peritoneal dialysis—< 10 mL per minute.




Aspirin—
        Renal, primarily as free salicylic acid and conjugated metabolites. There are large interindividual variations in elimination kinetics. Also, the rate of excretion of total salicylate and the quantity of free salicylic acid eliminated are increased in alkaline urine and decreased in acidic urine.


In dialysis—
        As salicylate—
        Hemodialysis: Clearances of 35 to 100 mL per minute have been reported.
        Peritoneal dialysis: Removed more slowly than with hemodialysis; clearances of 45 to 90 mL per hour have been reported in infants.





Salicylamide—
        Excreted as conjugated metabolites.



Caffeine—
        Renal, primarily as metabolites. About 10% of a dose is excreted unchanged.



Precautions to Consider

Cross-sensitivity and/or related problems


Acetaminophen

Patients sensitive to aspirin may not be sensitive to acetaminophen; however, mild bronchospastic reactions with acetaminophen have been reported in some aspirin-sensitive patients (less than 5% of those tested).



Salicylates

Patients sensitive to one salicylate, including methyl salicylate (oil of wintergreen), may be sensitive to other salicylates also. However, patients sensitive to aspirin may not necessarily be sensitive to salicylamide.

Patients sensitive to other nonsteroidal anti-inflammatory drugs (NSAIDs) also may be sensitive to salicylates, especially aspirin.


Pregnancy/Reproduction
Fertility—

Acetaminophen

Chronic toxicity studies in animals have shown that high doses of acetaminophen cause testicular atrophy and inhibition of spermatogenesis; the relevance of this finding to use in humans is not known.


Pregnancy—

Acetaminophen

Problems in humans have not been documented. Although controlled studies have not been done, it is known that acetaminophen crosses the placenta.



Salicylates


First trimester—

Salicylate readily crosses the placenta. It has been reported that aspirin use during pregnancy may increase the risk of birth defects in humans; however, controlled studies using usual therapeutic doses of aspirin have not shown proof of teratogenicity. Studies in humans with salicylamide have not been done.

Studies in animals have shown that aspirin causes increased fetal resorptions and birth defects, including fissure of the spine and skull; facial clefts; eye defects; and malformations of the CNS, viscera, and skeleton (especially the vertebrae and ribs).



Third trimester—

Pregnant women should not take aspirin during the last trimester unless aspirin therapy is prescribed and monitored by a physician. Chronic, high-dose aspirin therapy may result in prolonged gestation, increased risk of postmaturity syndrome (fetal damage or death due to decreased placental function when pregnancy is greatly prolonged), and increased risk of maternal prepartum hemorrhage.

Ingestion of aspirin during the last 2 weeks of pregnancy may increase the risk of fetal or neonatal hemorrhage. Also, the possibility must be considered that regular use of aspirin during late pregnancy may result in constriction or premature closure of the fetal ductus arteriosus, possibly leading to persistent pulmonary hypertension and heart failure in the neonate.

Overuse or abuse of aspirin late in pregnancy has been reported to reduce birth weight and to increase the risk of still birth or neonatal death, possibly because of prepartum maternal or fetal hemorrhage or premature ductus arteriosus closure; however, studies using therapeutic doses of aspirin have not shown these adverse effects.




Caffeine

Caffeine crosses the placenta and achieves blood and tissue concentrations in the fetus similar to maternal concentrations. Studies in humans have not shown that caffeine causes birth defects. However, excessive intake of caffeine by pregnant women has resulted in fetal arrhythmias. {09} {10} Also, a study demonstrated an elevated risk of intrauterine growth retardation and low birth weight to be associated with the intake of more than 300 mg of caffeine a day continuing past the 6th week of pregnancy. {11}

Studies in animals have shown that caffeine causes skeletal abnormalities in the digits and phalanges (when given in doses equivalent to the caffeine content of 12 to 24 cups of coffee daily throughout pregnancy or when given in very large single doses, i.e., 50 to 100 mg per kg of body weight [mg/kg]) and retarded skeletal development (when given in lower doses).



Aspirin—
Chronic, high-dose aspirin therapy late in pregnancy may result in prolonged labor, complicated deliveries, and increased risk of maternal or fetal hemorrhage.

Breast-feeding


Acetaminophen:

Problems in humans have not been documented. Although peak concentrations of 10 to 15 mcg per mL (66.2 to 99.3 micromoles/L) have been measured in breast milk 1 to 2 hours following maternal ingestion of a single 650-mg dose, neither acetaminophen nor its metabolites were detected in the urine of the nursing infants. The half-life in breast milk is 1.35 to 3.5 hours.



Aspirin:

Salicylate is distributed into breast milk; however, problems in humans with usual analgesic doses have not been documented.

In one study, peak salicylate concentrations of 173 to 483 mcg per mL (17.3 to 48.3 mg per 100 mL [1.25 to 3.5 mmol/L]) were measured in breast milk 5 to 8 hours after maternal ingestion of a single 650-mg dose of aspirin. The half-life in breast milk was 3.8 to 12.5 hours (average 7.1 hours).



Caffeine:

Caffeine is distributed into breast milk in very small amounts; at recommended doses of caffeine-containing analgesic combinations, concentration in the infant is considered insignificant. However, it is recommended that breast-feeding mothers limit their total daily intake of caffeine to the quantity contained in 1 or 2 cups of caffeine-containing beverages. The beverage with the highest caffeine content is nondecaffeinated brewed coffee, 2 cups of which may provide up to 360 mg of caffeine. Accumulation of caffeine in the infant, leading to signs of caffeine stimulation such as hyperactivity and wakefulness, may occur when a breast-feeding mother ingests large quantities of caffeine (i.e., 6 to 8 cups of caffeine-containing beverages a day). {12}


Pediatrics


All acetaminophen and salicylate combinations:

The use of acetaminophen and salicylate combinations in children is controversial. Many clinicians recommend that these medications not be given to children younger than 12 years of age. However, other clinicians state that these medications may be given to children, provided that proper dosage can be achieved with the individual product. {13}


Acetaminophen—

Studies performed to date have not demonstrated pediatrics-specific problems that would limit the usefulness of acetaminophen in children.



Salicylates—

Use of a salicylate may be associated with the development of Reye"s syndrome in children with acute febrile illnesses, especially influenza and varicella. It is recommended that a salicylate not be administered to febrile pediatric patients until after the presence of such an illness has been ruled out. {14}

Pediatric patients, especially those with fever and dehydration, may be more susceptible to the toxic effects of salicylates.



Caffeine—

Appropriate studies on the relationship of age to the effects of caffeine have not been performed in children younger than 12 years of age. However, no pediatrics-specific problems have been documented to date. {15}





Adolescents

Use of a salicylate may be associated with the development of Reye"s syndrome in adolescents with acute febrile illnesses, especially influenza and varicella. It is recommended that aspirin not be administered to febrile adolescent patients until after the presence of such an illness has been ruled out. {14}


Geriatrics



All acetaminophen and salicylate combinations:

Geriatric patients are more likely to have age-related renal function impairment, which may increase susceptibility to the adverse renal effects of combinations containing two or more analgesic/antipyretic medications. Geriatric patients should preferably not take these medications for longer than 5 days at a time unless more prolonged therapy is prescribed and monitored by a physician.



Acetaminophen:

Studies performed to date have not demonstrated geriatrics-specific problems that would limit the usefulness of acetaminophen in the elderly.



Aspirin:

Geriatric patients may be more susceptible to the toxic effects of salicylates.



Caffeine:

No information is available on the relationship of age to the effects of caffeine in geriatric patients.


Drug interactions and/or related problems
The following drug interactions and/or related problems have been selected on the basis of their potential clinical significance (possible mechanism in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):


Note: Combinations containing any of the following medications, depending on the amount present, may also interact with this medication.
In addition to the interactions listed below, the possibility should be considered that additive or multiple effects leading to impaired blood clotting and/or increased risk of bleeding may occur if a salicylate, especially aspirin, is used concurrently with any medication having a significant potential for causing hypoprothrombinemia, thrombocytopenia, or gastrointestinal ulceration or hemorrhage.


For acetaminophen
» Alcohol, especially chronic abuse of or
Hepatic enzyme inducers (see Appendix II ) or
Hepatotoxic medications, other (see Appendix II )    (risk of hepatotoxicity with single toxic doses or prolonged use of high doses of acetaminophen may be increased in alcoholics, in patients who consume three or more alcoholic beverages per day, or in patients regularly taking other hepatotoxic medications or hepatic enzyme inducers)

    (chronic use of barbiturates [except butalbital] or primidone has been reported to decrease the therapeutic effects of acetaminophen, probably because of increased metabolism resulting from induction of hepatic microsomal enzyme activity; the possibility should be considered that similar effects may occur with other hepatic enzyme inducers)


Anticoagulants, coumarin- or indanedione-derivative    (concurrent chronic, high-dose administration of acetaminophen may increase the anticoagulant effect, possibly by decreasing hepatic synthesis of procoagulant factors; anticoagulant dosage adjustment based on increased monitoring of prothrombin time may be necessary when chronic, high-dose acetaminophen therapy is initiated or discontinued; however, this does not apply to occasional use or to chronic use of doses below 2 grams per day of acetaminophen)


Anti-inflammatory drugs, nonsteroidal (NSAIDs) or
Aspirin or other salicylates    (prolonged concurrent use of acetaminophen with a salicylate is not recommended because recent evidence suggests that chronic, high-dose administration of the combined analgesics [1.35 grams daily, or cumulative ingestion of 1 kg annually, for 3 years or longer] significantly increases the risk of analgesic nephropathy, renal papillary necrosis, end-stage renal disease, and cancer of the kidney or urinary bladder; also, it is recommended that for short-term use, the combined dose of acetaminophen plus salicylate not exceed that recommended for acetaminophen or a salicylate given alone)

    (diflunisal may increase the plasma concentration of acetaminophen by 50%, leading to increased risk of hepatotoxicity)

    (prolonged concurrent use of acetaminophen with NSAIDs other than aspirin may also increase the risk of adverse renal effects; it is recommended that patients be under close medical supervision while receiving such combined therapy)


For aspirin
Acidifiers, urinary, such as
Ammonium chloride
Ascorbic acid
Potassium or sodium phosphates    (acidification of the urine by these medications decreases salicylate [from aspirin] excretion, leading to increased salicylate plasma concentrations)


Alcohol or
» Anti-inflammatory drugs, nonsteroidal (NSAIDs), other or
Corticosteroids, glucocorticoid or
Corticotropin, chronic therapeutic use    (risk of gastrointestinal side effects, including ulceration and gastrointestinal blood loss, may be increased when these agents are used concurrently with aspirin; also, concurrent use of aspirin and other NSAIDs may not provide additional symptomatic relief and is therefore not recommended)

    (aspirin may decrease the bioavailability of many NSAIDs, including diflunisal, fenoprofen, indomethacin, ketoprofen, meclofenamate, piroxicam, and the active sulfide metabolite of sulindac)


» Alkalizers, urinary, such as:
Carbonic anhydrase inhibitors
Citrates or
Antacids, chronic high-dose use, especially calcium- or magnesium-containing or sodium bicarbonate    (alkalinization of the urine by these agents increases salicylate [from aspirin] excretion, leading to decreased salicylate plasma concentrations, reduced effectiveness, and shortened duration of analgesic action)

    (carbonic anhydrase inhibitors may also increase the risk of salicylate intoxication in patients receiving large doses of aspirin because metabolic acidosis induced by carbonic anhydrase inhibitors may increase penetration of salicylate into the brain; the increased risk of severe metabolic acidosis and salicylate toxicity must be considered if acetazolamide is used to produce forced alkaline diuresis in the treatment of aspirin overdose)


» Anticoagulants, coumarin- or indanedione-derivative or
» Heparin or
» Thrombolytic agents, such as:
Alteplase
Anistreplase
Streptokinase
Urokinase    (aspirin may displace a coumarin- or indanedione-derivative anticoagulant from its protein-binding sites and, in high doses, may decrease hepatic synthesis of procoagulant factors, leading to increased anticoagulation and risk of bleeding)

    (concurrent use with combinations containing aspirin is not recommended because aspirin-induced inhibition of platelet function may lead to prolonged bleeding time and hemorrhage in patients receiving anticoagulant or thrombolytic therapy)

    (the potential occurrence of gastrointestinal ulceration or hemorrhage during therapy with aspirin may increase risks to patients receiving anticoagulant or thrombolytic therapy)


Anticonvulsants, hydantoin{29}{30}{31}{32}{33}    (aspirin may decrease metabolism of hydantoin anticonvulsants, leading to increased serum concentrations and to increased therapeutic and/or toxic effects of the anticonvulsant; adjustment of hydantoin dosage may be necessary)


» Antidiabetic agents, oral or
Insulin    (effects of these medications may be increased by large doses of aspirin; dosage adjustments may be necessary; potentiation of oral antidiabetic agents may partially be caused by displacement from serum proteins; glipizide and glyburide, because of their nonionic binding characteristics, may not be affected as much as the other oral agents; however, caution in concurrent use is recommended)


Antiemetics, including antihistamines and phenothiazines    (antiemetics may mask the symptoms of aspirin-induced ototoxicity, such as dizziness, vertigo, and tinnitus)


Bismuth subsalicylate    (ingestion of large repeated doses, as for traveler's diarrhea, may produce substantial plasma salicylate concentrations; concurrent use with large doses of analgesic salicylates may increase the risk of salicylate toxicity)


» Cefamandole or
» Cefoperazone or
» Cefotetan or
» Plicamycin    (these medications may cause hypoprothrombinemia; in addition, plicamycin may inhibit platelet aggregation; concurrent use with aspirin may increase the risk of bleeding because of additive interferences with blood clotting and/or the potential occurrence of gastrointestinal ulceration or hemorrhage during aspirin therapy)


Furosemide    (in addition to an increased risk of ototoxicity, concurrent use of furosemide with high doses of aspirin may lead to salicylate toxicity because of competition for renal excretory sites)


Laxatives, cellulose-containing    (concurrent use may reduce the salicylate effect because of physical binding or other absorptive hindrance; medications should be administered 2 hours apart)


» Methotrexate    (aspirin may displace methotrexate from its binding sites and decrease its renal clearance, leading to toxic plasma concentrations of methotrexate; if used concurrently, methotrexate dosage should be decreased, the patient observed for signs of toxicity, and/or methotrexate plasma concentration monitored; also, it is recommended that salicylate therapy be discontinued 24 to 48 hours prior to administration of a high-dose methotrexate infusion, and not resumed until plasma methotrexate concentrations have decreased to a nontoxic level [usually at least 12 hours postinfusion])


Ototoxic medications, other (see Appendix II ), especially
» Vancomycin    (concurrent or sequential administration of these medications with aspirin should be avoided because the potential for ototoxicity may be increased; hearing loss may occur and may progress to deafness even after discontinuation of the medication; these effects may be reversible, but usually are permanent)


» Platelet aggregation inhibitors, other (see Appendix II )    (concurrent use with combinations containing aspirin is not recommended because of the increased risk of hemorrhage resulting from additive inhibition of platelet aggregation, the potential occurrence of gastrointestinal ulceration or hemorrhage during aspirin therapy, and the hypoprothrombinemic effect of large doses of aspirin)


» Probenecid or
» Sulfinpyrazone    (uricosuric effects of probenecid or sulfinpyrazone may be decreased by doses of aspirin that produce serum salicylate concentrations above 50 mcg per mL [5 mg per 100 mL; 0.36 mmol/L]; also, probenecid may decrease renal clearance and increase plasma concentrations of salicylate, thereby increasing the risk of toxicity)

    (sulfinpyrazone may decrease salicylate [from aspirin] excretion and/or displace salicylate from its protein binding sites, possibly leading to increased salicylate concentrations and toxicity)

    (concurrent use of sulfinpyrazone with aspirin may increase the risk of gastrointestinal ulceration or hemorrhage; also, concurrent use of sulfinpyrazone with aspirin may increase the risk of bleeding at sites other than the gastrointestinal tract because of additive inhibition of platelet aggregation)


Salicylic acid (topical)    (concurrent use with aspirin may increase the risk of salicylate toxicity if significant quantities are absorbed)


Vitamin K    (requirements for this vitamin may be increased in patients receiving high doses of aspirin)


For formulations containing caffeine (in addition to the interactions listed above for acetaminophen or for aspirin)
CNS stimulation–producing medications, other (see Appendix II )    (concurrent use with caffeine may result in excessive CNS stimulation, leading to unwanted effects such as nervousness, irritability, insomnia, or possibly convulsions or cardiac arrhythmias; close observation is recommended)


Lithium    (caffeine increases urinary excretion of lithium, and may thereby reduce its therapeutic effect)


Monoamine oxidase (MAO) inhibitors, including furazolidone, procarbazine, and selegiline    (the sympathomimetic side effects of caffeine may cause dangerous cardiac arrhythmias or severe hypertension when large amounts of caffeine are used concurrently with MAO inhibitors)


For formulations containing buffering agents (in addition to the interactions listed above for other specific ingredients)
Other medications, oral, especially:
» Ciprofloxacin{34}
» Enoxacin{35}
» Itraconazole{36}
» Ketoconazole{16}
» Lomefloxacin{37}
» Norfloxacin{38}
» Ofloxacin{39}
» Tetracyclines{16}    (antacids present as buffering agents in analgesic products may interfere with the absorption of many other orally administered medications; if used concurrently, a buffered analgesic product should be taken at least 6 hours before or 2 hours after ciprofloxacin or lomefloxacin, 8 hours before or 2 hours after enoxacin, 2 hours after itraconazole, 3 hours before or after ketoconazole, 2 hours before or after norfloxacin or ofloxacin, 3 to 4 hours before or after tetracycline, and at least 1 to 2 hours before or after other orally administered medications)



Laboratory value alterations
The following have been selected on the basis of their potential clinical significance (possible effect in parentheses where appropriate)—not necessarily inclusive (» = major clinical significance):

With diagnostic test results
For acetaminophen
Glucose, blood    (values may be falsely decreased by acetaminophen when measured by the glucose oxidase/peroxidase method but probably not when measured by the hexokinase/glucose-6-phosphate dehydrogenase [G6PD] method)

    (values may be falsely increased when certain instruments are used in glucose analysis if high acetaminophen concentrations are present; consult manufacturer's instruction manual)


5-Hydroxyindoleacetic acid (5-HIAA), serum    (acetaminophen may cause false-positive results in qualitative screening tests using nitrosonaphthol reagent; the quantitative test is unaffected)


Pancreatic function determinations using bentiromide    (administration of acetaminophen prior to the bentiromide test will invalidate test results because acetaminophen is also metabolized to an arylamine and will thus increase the apparent quantity of para-aminobenzoic acid [PABA] recovered; it is recommended that acetaminophen be discontinued at least 3 days prior to administration of bentiromide)


Uric acid, serum    (falsely increased values may occur when the phosphotungstate uric acid test method is used)

For aspirin
Copper sulfate urine sugar tests    (false-positive test results may occur with chronic use of 2.4 grams or more a day)


Gerhardt's test for urine acetoacetic acid    (interference may occur because reaction with ferric chloride produces a reddish color that persists after boiling)


Glucose enzymatic urine sugar tests    (false-negative test results may occur with chronic use of 2.4 grams or more a day)


5-Hydroxyindoleacetic acid (5-HIAA), urine    (aspirin may alter results when fluorescent method is used)


Protirelin-induced thyroid-stimulating hormone (TSH) release determinations    (TSH response to protirelin may be decreased by 2 to 3.6 grams of aspirin daily; peak TSH concentrations occur at the same time after administration, but are reduced)


Renal function test using phenolsulfonphthalein (PSP)    (salicylate [from aspirin] may competitively inhibit renal tubular secretion of PSP, thereby decreasing urinary PSP concentration and invalidating test results)


Thyroid imaging, radionuclide    (chronic aspirin administration may depress thyroid function; aspirin therapy should be discontinued at least 1 week prior to administration of the radiopharmaceutical; however, a rebound effect may occur following discontinuation of salicylate therapy, resulting in a period of 3 to 10 days of increased thyroidal uptake {17})


Vanillylmandelic acid (VMA), urine    (values may be falsely increased or decreased, depending on method used)

For caffeine
Myocardial perfusion imaging, radionuclide, when adenosine or{18} dipyridamole is used as an adjunct to the radiopharmaceutical    (caffeine may reverse the effects of adenosine {18} or dipyridamole on myocardial blood flow, thereby interfering with test results; patients should be advised to avoid caffeine for 8 to 12 {19} hours prior to the test)

With physiology/laboratory test values
For acetaminophen
Bilirubin concentrations, serum and
Lactate dehydrogenase values, serum and
Prothrombin time and
Transaminase values, serum    (may be increased indicating acetaminophen-induced hepatotoxicity, especially in alcoholics, patients taking hepatic enzyme–inducing agents, or those with pre-existing hepatic disease, when single toxic doses [> 8-10 grams] are taken or with prolonged use of lower doses [> 3-5 grams a day])

For aspirin
Bleeding time    (may be prolonged by aspirin for 4 to 7 days because of suppressed platelet aggregation; as little as 40 mg of aspirin affects platelet function for at least 96 hours following administration; however, clinical bleeding problems have not been reported with small doses [150 mg or less])


Cholesterol, serum    (concentrations may be decreased by chronic use of 5 grams or more per day)


Potassium, serum    (concentrations may be decreased because of increased potassium excretion caused by direct effect on renal tubules)


Uric acid, serum    (concentrations may be increased with doses producing plasma salicylate concentrations below 100 to 150 mcg per mL [10 to 15 mg per 100 mL; 0.724 to 1.09 mmol/L] or decreased with doses producing plasma salicylate concentrations above 100 to 150 mcg per mL [10 to 15 mg per 100 mL; 0.724 to 1.09 mmol/L])


Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).


Except under special circumstances, this medication should not be used when the following medical problems exist:

For aspirin:
» Angioedema, anaphylaxis, or other severe allergic reaction induced by aspirin or other NSAIDs, history of    (high risk of recurrence)


» Bleeding ulcers or
» Hemorrhagic states, other, active    (may be exacerbated because of antiplatelet action of aspirin and decreased procoagulant factor synthesis [with high doses])


» Hemophilia or other bleeding problems, including coagulation or platelet function disorders    (increased risk of hemorrhage)


Risk-benefit should be considered when the following medical problems exist

For acetaminophen:
» Alcoholism (active) or
» Hepatic disease or
» Viral hepatitis    (increased risk of hepatotoxicity)


Renal function impairment, severe    (risk of adverse renal effects may be increased with prolonged use of high doses; occasional use is acceptable)


Sensitivity to acetaminophen, history of
For aspirin:
Anemia    (may be exacerbated because of increased gastrointestinal blood loss; also, pseudoanemia may result from peripheral vasodilation)


» Asthma, allergies, and nasal polyps, aspirin-sensitivity induced or
Mild sensitivity reaction to aspirin, history of    (increased risk of severe allergic reactions)


» Gastritis, erosive or
» Peptic ulcer    (may be exacerbated because of ulcerogenic effects; risk of gastrointestinal bleeding is increased)


Gout    (aspirin may increase serum uric acid concentrations; also, may interfere with efficacy of uricosuric agents)


Hepatic function impairment    (salicylates metabolized in liver; also, in severe hepatic impairment, inhibition of platelet function by aspirin may increase risk of hemorrhage)


Hypoprothrombinemia or
Vitamin K deficiency    (increased risk of bleeding because of antiplatelet action of aspirin and decreased procoagulant factor synthesis with high doses)


Renal function impairment    (salicylates excreted via kidneys)


For formulations containing caffeine (in addition to those listed above for acetaminophen or for aspirin):
Cardiac disease, severe    (high doses of caffeine may increase risk of tachycardia or extrasystoles, which may lead to heart failure)


Sensitivity to caffeine, history of

Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):

Hepatic function determinations    (may be required at periodic intervals during high-dose or long-term acetaminophen therapy)


Renal function determinations    (may be advisable at periodic intervals during and following prolonged use of high doses of acetaminophen and salicylate combinations because of the risk of analgesic nephropathy)




Side/Adverse Effects

Note: Abuse of combinations of analgesic/antipyretic medications (defined as chronic ingestion of 1.35 grams of the medications per day or cumulative ingestion of 1 kg of the medications annually) for 3 years or longer may lead to severe analgesic nephropathy, including renal papillary necrosis and end-stage renal disease, and cancer of the kidney or urinary bladder. Although phenacetin has been suspected of being the causative agent, there is some evidence that the risk of analgesic nephropathy is significantly greater with prolonged concurrent use of two or more analgesic/antipyretic medications (including combinations of acetaminophen with aspirin, other salicylates, and possibly nonsteroidal anti-inflammatory drugs other than aspirin) than with use of a single analgesic/antipyretic agent. However, renal tubular necrosis has been reported in severe acetaminophen overdose. Also, although a causal association has not been established, a retrospective study has suggested that long-term daily use of acetaminophen alone may be associated with an increased risk of analgesic nephropathy. {20}
The caffeine in some of the formulations may contribute to analgesic abuse because of its CNS-stimulating effects and because discontinuation of caffeine may lead to withdrawal headache. {21} {22} {23}
Aspirin-induced bronchospasm is most likely to occur in patients with the triad of aspirin-induced asthma, allergies, and nasal polyps. Aspirin-induced angioedema or urticaria may be more likely to occur in patients with a history of recurrent idiopathic angioedema or urticaria.
Gastrointestinal side effects are more likely to occur with aspirin than with other salicylates.

The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
Incidence less frequent or rare
For aspirin
    
Anaphylaxis (bluish discoloration or flushing or redness of skin; coughing; difficulty in swallowing; dizziness or feeling faint, severe; skin rash, hives [may include giant urticaria], and/or itching; stuffy nose; swelling of eyelids, face, or lips; tightness in chest, troubled breathing, and/or wheezing, especially in asthmatic patients)
    
anemia (unusual tiredness or weakness)—may occur secondary to gastrointestinal microbleeding
    
bronchospastic allergic reaction (shortness of breath, troubled breathing, tightness in chest, and/or wheezing)
    
dermatitis, allergic (skin rash, hives, or itching)
    
gastrointestinal ulceration, possibly with bleeding (bloody or black, tarry stools; stomach pain, severe; vomiting of blood or material that looks like coffee grounds)


Incidence rare
For acetaminophen
    
Agranulocytosis (fever with or without chills; sores, ulcers, or white spots on lips or in mouth; sore throat)
    
anemia (unusual tiredness or weakness)
    
dermatitis, allergic (skin rash, hives, or itching)
    
hepatitis (yellow eyes or skin)
    
renal colic (pain, severe and/or sharp, in lower back and/or side)—with prolonged use of high doses in patients with severe renal function impairment
    
renal failure (sudden decrease in amount of urine)—with prolonged use of high doses in patients with renal function impairment; may progress to uremia
    
sterile pyuria (cloudy urine)
    
thrombocytopenia (usually asymptomatic; rarely, unusual bleeding or bruising; black, tarry stools; blood in urine or stools; pinpoint red spots on skin)




Those indicating possible analgesic nephropathy and the need for medical attention if they occur during or following long-term, high-dose use
Incidence rare
    
Renal papillary necrosis leading to renal failure (bloody or cloudy urine; sudden decrease in amount of urine; swelling of face, fingers, feet, or lower legs; weight gain)—may progress to uremia



Those indicating need for medical attention only if they continue or are bothersome
Incidence more frequent
For aspirin
    
Gastrointestinal irritation (mild stomach pain; heartburn or indigestion; nausea with or without vomiting)


Incidence less frequent
For salicylamide
    
Drowsiness

For caffeine-containing formulations
    
CNS stimulation (trouble in sleeping, nervousness, or jitters)






Overdose
For specific information on the agents used in the management of acetaminophen and salicylates overdose, see:    • Acetylcysteine (Systemic) monograph;
   • Charcoal, Activated (Oral-Local); and/or
   • Vitamin K 1 —Phytonadione in Vitamin K (Systemic) monograph.


For more information on the management of overdose or unintentional ingestion, contact a Poison Control Center (see Poison Control Center Listing ).

Clinical effects of overdose
The following effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Acetaminophen
    
Diarrhea
increased sweating
loss of appetite
nausea or vomiting
stomach cramps or pain —these acute symptoms may occur within 6 to 14 hours after ingestion of the overdose and persist for about 24 hours

Note: Early signs and symptoms often do not occur.


    
Hepatotoxicity (pain, tenderness, and/or swelling in upper abdominal area)—these chronic symptoms may occur 2 to 4 days after the overdose is ingested

Note: The first indications of overdosage may be signs and symptoms of possible liver damage and abnormalities in liver function tests, which may not occur until 2 to 4 days after ingestion of the overdose. Maximal changes in liver function tests usually occur 3 to 5 days after ingestion of the overdose.
Overt hepatic disease or failure may occur 4 to 6 days after ingestion of the overdose. Hepatic encephalopathy (with mental changes, confusion, agitation, or stupor), convulsions, respiratory depression, coma, cerebral edema, coagulation defects, gastrointestinal bleeding, disseminated intravascular coagulation, hypoglycemia, metabolic acidosis, renal tubular necrosis leading to renal failure (signs include bloody or cloudy urine and sudden decrease in amount of urine), cardiac arrhythmias, and cardiovascular collapse may occur.



Aspirin
Acute and chronic
    
Continuing ringing or buzzing in ears, or hearing loss
confusion
severe or continuing diarrhea
stomach pain, and/or headache
dizziness or lightheadedness
severe drowsiness
fast or deep breathing
continuing nausea and/or vomiting
uncontrollable flapping movements of the hands, especially in elderly patients
increased thirst
vision problems —symptoms of a mild overdose [salicylism]

    
Bloody urine
convulsions
hallucinations
severe nervousness, excitement, or confusion
shortness of breath or troubled breathing
unexplained fever —symptoms of severe overdose
Note: In young children, the only signs of an overdose may be changes in behavior, severe drowsiness or tiredness, and/or fast or deep breathing.
Laboratory findings in overdose may indicate encephalographic abnormalities, alterations in acid-base balance (especially respiratory alkalosis and metabolic acidosis), hyperglycemia or hypoglycemia (especially in children), ketonuria, hyponatremia, hypokalemia, and proteinuria.





Caffeine
Acute and chronic {24}
    
Abdominal or stomach pain
    
agitation, anxiety, excitement, or restlessness
    
confusion or delirium
    
dehydration
    
fast or irregular heartbeat
    
fever
    
frequent urination
    
headache
    
increased sensitivity to touch or pain
    
irritability
    
muscle trembling or twitching
    
nausea and vomiting, sometimes with blood
    
ringing or other sounds in ears
    
seeing flashes of ``zig-zag'' lights
    
seizures, usually tonic-clonic seizures
    
trouble in sleeping





Treatment of overdose


Acetaminophen and aspirin:
To decrease absorption: Emptying the stomach via induction of emesis or gastric lavage.

Administering activated charcoal. However, activated charcoal may interfere with absorption of oral acetylcysteine (antidote used to protect against acetaminophen-induced hepatotoxicity); removal of activated charcoal via gastric lavage may be advisable prior to acetylcysteine administration.

Supportive care—Monitoring and supporting vital functions.



Acetaminophen:
To enhance elimination: Instituting hemodialysis or hemoperfusion to remove acetaminophen from the circulation may be beneficial if acetylcysteine administration cannot be instituted within 24 hours following ingestion of a massive acetaminophen overdose. However, the efficacy of this treatment in preventing acetaminophen-induced hepatotoxicity is not known.

Specific treatment: Administering acetylcysteine. It is recommended that acetylcysteine administration be instituted as soon as possible after ingestion of an overdose has been reported, without waiting for the results of plasma acetaminophen determinations or other laboratory tests. Acetylcysteine is most effective if treatment is started within 10 to 12 hours after ingestion of the overdose; however, it may be of some benefit if treatment is started within 24 hours. See the package insert or Acetylcysteine (Systemic) for specific dosing guidelines for use of this product.

Monitoring: Determining plasma acetaminophen concentration at least 4 hours following ingestion of the overdose. Determinations performed prior to this time are not reliable for assessing potential hepatotoxicity. Initial plasma concentrations above 150 mcg per mL (993 micromoles/L) at 4 hours, 100 mcg per mL (662 micromoles/L) at 6 hours, 70 mcg per mL (463.4 micromoles/L) at 8 hours, 50 mcg per mL (331 micromoles/L) at 10 hours, 20 mcg per mL (132.4 micromoles/L) at 15 hours, 8 mcg per mL (53 micromoles/L) at 20 hours, or 3.5 mcg per mL (23.2 micromoles/L) at 24 hours postingestion indicate possible hepatotoxicity and the need for completing the full course of acetylcysteine treatment. If the initial determination indicates a plasma concentration below those listed at the times indicated, cessation of acetylcysteine therapy can be considered. However, some clinicians advise that more than one determination should be performed to ascertain peak absorption and half-life of acetaminophen prior to considering discontinuation of acetylcysteine.

Performing liver function tests (serum aspartate aminotransferase [AST; SGOT], serum alanine aminotransferase [ALT; SGPT], prothrombin time, and bilirubin) at 24-hour intervals for at least 96 hours postingestion if the plasma acetaminophen concentration indicates potential hepatotoxicity. If no abnormalities are detected within 96 hours, further determinations are not needed.

Monitoring renal and cardiac function and administering appropriate therapy as required.

Supportive care: Instituting supportive treatment, including maintaining fluid and electrolyte balance, correcting hypoglycemia, and administering vitamin K 1 (if prothrombin time ratio exceeds 1.5) and fresh frozen plasma or clotting factor concentrate (if prothrombin time ratio exceeds 3).



Aspirin:
To enhance elimination: Inducing forced alkaline diuresis to increase salicylate excretion. However, bicarbonate should not be administered orally for this purpose because salicylate absorption may be increased. Also, if acetazolamide is used, the increased risk of severe metabolic acidosis and salicylate toxicity (caused by increased penetration of salicylate into the brain because of metabolic acidosis) must be considered. Some emergency care practitioners recommend that acetazolamide not be used at all in the treatment of salicylate overdose. {27} Others state that acetazolamide may be used, provided that precautions are taken to prevent systemic metabolic acidosis, such as concurrent administration of an alkaline intravenous solution, e.g., one that contains sodium bicarbonate or sodium lactate. {19}

Institution of exchange transfusion, hemodialysis, peritoneal dialysis, or hemoperfusion as needed in severe overdose.

Specific treatment: Administering blood or vitamin K 1 if necessary to treat hemorrhaging. See the package insert or Vitamin K 1 —Phytonadione in Vitamin K (Systemic) .

Monitoring: Serum salicylate concentration should be monitored until it is apparent that the concentration is decreasing to the nontoxic range. Salicylate concentrations of 500 mcg per mL (50 mg per 100 mL; 3.62 mmol/L) 2 hours after ingestion indicate serious toxicity; salicylate concentrations above 800 mcg per mL (80 mg per 100 mL; 5.79 mmol/L) 2 hours after ingestion indicate possible fatality. In addition, prolonged monitoring may be necessary in massive overdosage because absorption may be delayed; if a determination performed prior to 6 hours after ingestion fails to show a toxic salicylate concentration, the determination should be repeated. {25} Salicylate concentrations indicative of varying degrees of toxicity are as follows: {26}

Time after
ingestion
Salicylate concentration
mcg/mL
mg/100 mL
mmol/L
Mild toxicity
     
6 hr
450–650
45–65
3.26–4.71
12 hr
350–550
35–55
2.53–3.98
Moderate toxicity
     
6 hr
650–900
65–90
4.71–6.52
12 hr
550–750
55–75
3.98–5.43
Severe toxicity
     
6 hr
> 900
> 90
> 6.52
12 hr
> 750
> 75
> 5.43


Monitoring: Monitoring for pulmonary edema and instituting appropriate therapy if required.

Correcting hyperthermia; fluid, electrolyte, and acid-base imbalances; ketosis; and plasma glucose concentration as needed.

Patients in whom intentional overdose is confirmed or suspected should be referred for psychiatric consultation.



Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Acetaminophen and Salicylates (Systemic) .

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Before using this medication
»   Conditions affecting use, especially:
Sensitivity to acetaminophen, aspirin, or nonsteroidal anti-inflammatory drugs (NSAIDs)

Pregnancy—Not taking aspirin in third trimester unless prescribed by physician; high-dose chronic use or abuse of aspirin in third trimester may be hazardous to the mother as well as the fetus and/or neonate, causing heart problems in fetus or neonate and/or bleeding in mother, fetus, or neonate; high-dose chronic use or abuse may also prolong and complicate labor and delivery; large quantities of caffeine may cause arrhythmias and growth retardation in the fetus




Use in children——Checking with physician before giving a salicylate to children with symptoms of acute febrile illness, especially influenza or varicella, because of the risk of Reye's syndrome; also, increased susceptibility to aspirin toxicity in children, especially with fever and dehydration




Use in adolescents—
Checking with physician before giving a salicylate to teenagers with symptoms of acute febrile illness, especially influenza or varicella, because of the risk of Reye's syndrome





Use in the elderly—— Increased risk of aspirin toxicity and of combination analgesic–induced adverse renal effects
Other medications, especially alcohol, anticoagulants, antidiabetic agents (oral), those cephalosporins that may cause hypoprothrombinemia, heparin, methotrexate, NSAIDs, platelet aggregation inhibitors, plicamycin, probenecid, sulfinpyrazone, and urinary alkalizers and, for buffered formulations, fluoroquinolone antibiotics, itraconazole, ketoconazole, oral tetracyclines, thrombolytic agents, and vancomycin
Other medical problems, especially alcoholism (active), asthma, coagulation or platelet function disorders, gastrointestinal problems such as ulceration or erosive gastritis (especially a bleeding ulcer), and hepatic disease or viral hepatitis

Proper use of this medication
» Taking with food or a full glass (240 mL) of water to minimize gastrointestinal irritation

» Importance of not taking more medication than recommended on package label, unless otherwise directed by physician, because of risk of acetaminophen-induced liver damage with long-term use or greater-than-recommended doses, gastrointestinal toxicity with salicylates, and acetaminophen or salicylate overdose

» Importance of children not receiving more than five doses per day unless otherwise directed by physician

» Not taking for chronic or severe inflammatory or rheumatic conditions without first checking with physician because prolonged treatment may be necessary and medication may not be effective unless extremely high doses are taken

» Not taking combinations containing aspirin if a strong vinegar-like odor is present

» Proper dosing

» Proper storage

Precautions while using this medication
» Regular visits to physician to check progress if long-term or high-dose therapy is prescribed

Checking with physician because additional treatment may be needed:

   —if taking for pain or fever, and pain persists for longer than 10 days (5 days for children) or fever persists for longer than 3 days, if condition becomes worse, if new symptoms occur, or if the painful area is red or swollen
   —if taking for sore throat, and sore throat is severe, persists for longer than 2 days, or occurs together with or is followed by fever, headache, rash, nausea, or vomiting


Not taking products containing aspirin for 5 days prior to any kind of surgery, unless otherwise directed by physician

» Caution if other medications containing acetaminophen, aspirin, or other salicylates (including diflunisal) are used

» Checking with physician if you consume three or more alcohol-containing beverages per day; alcohol consumption may increase risk of salicylate-induced gastrointestinal toxicity and acetaminophen-induced liver toxicity

» Not using an NSAID together with this medication for more than a few days, unless directed by physician or dentist

» Not taking buffered formulations within 6 hours before or 2 hours after ciprofloxacin or lomefloxacin, 8 hours before or 2 hours after enoxacin, 2 hours after itraconazole, 3 hours before or after ketoconazole, 2 hours before or after norfloxacin or ofloxacin, 3 to 4 hours before or after an oral tetracycline, or 1 to 2 hours before or after other oral medications

Not taking a cellulose-containing laxative within 2 hours of aspirin-containing medications

Possible interference with some laboratory tests; preferably discussing use of the medication with physician in charge 3 to 4 days ahead of time; if this is not possible, informing physician in charge if medication taken within the past 3 or 4 days

Patients with diabetes: Possible false results with blood and urine glucose tests; checking with physician, nurse, or pharmacist if changes in test results noted

Not taking caffeine-containing formulations for 8 to 12 hours prior to adenosine- or dipyridamole-assisted myocardial perfusion imaging test

» Suspected overdose: Getting emergency help at once


Side/adverse effects
Signs of potential side effects, especially allergic reactions, anemia, gastrointestinal toxicity, agranulocytosis, hepatotoxicity, renal failure, sterile pyuria, and thrombocytopenia.


General Dosing Information
Doses are stated in terms of total analgesics present in these combination medications. They are based on USP Advisory Panel recommendations that the total dose of analgesic/antipyretic agents given in combination should be equivalent to the dose recommended for an individual analgesic/antipyretic agent used alone. The stated doses are those proposed by the FDA for over-the-counter (OTC) use of acetaminophen or aspirin given individually. The strengths of individual products, and the doses recommended by manufacturers of individual products, may not conform to the recommended doses.

Medications containing aspirin should be administered with food or a full glass (240 mL) of water to lessen gastric irritation.

Dosage of aspirin should be reduced if fever or illness causes fluid depletion, especially in children.

Because of the possibility of analgesic nephropathy resulting from long-term, high-dose use of analgesic combinations, and possibly even acetaminophen alone, prolonged daily use of these medications probably should be limited to patients who are receiving appropriate medical supervision. {13}

In general, it is recommended that aspirin therapy be discontinued 5 days before surgery to reduce the risk of bleeding problems.

ACETAMINOPHEN AND ASPIRIN


Oral Dosage Forms

ACETAMINOPHEN, ASPIRIN, AND CAFFEINE ORAL POWDERS

Usual adult and adolescent dose
Analgesic or
Antipyretic
Oral, up to a total of approximately 780 mg of acetaminophen and aspirin (combined) every four to six hours as needed, while symptoms persist. {04} {13}


Note: For patient self-medication, it is recommended that a physician be consulted if pain is not relieved within ten days, fever within three days, or sore throat within two days. {04} {13}
For geriatric patients, it may be advisable that acetaminophen and salicylate combinations not be used for longer than five days at a time, because such patients may be more susceptible to adverse renal effects.


Usual adult prescribing limits
For short-term therapy (up to ten days)—A total of approximately 4 grams of acetaminophen and aspirin (combined) daily. {04} {13}

For long-term therapy—A total of approximately 2.6 grams of acetaminophen and aspirin (combined) daily, unless chronic treatment with higher doses is prescribed and monitored by a physician. {13}

Usual pediatric dose
Product of suitable strength not available.

Usual geriatric dose

See Usual adult and adolescent dose . Dosing is based only on the analgesic ingredients.

Note: Because geriatric patients may be more susceptible to adverse renal effects, it may be advisable that they not use acetaminophen and salicylate combinations for longer than five days at a time.


Strength(s) usually available
U.S.—


260 mg of acetaminophen, 520 mg of aspirin, and 32.5 mg of caffeine (OTC) [Goody's Headache Powders{01} (lactose)]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a well-closed container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Avoid alcoholic beverages.
   • Take with a full glass of water or other liquid.


ACETAMINOPHEN, ASPIRIN, AND CAFFEINE TABLETS USP

Usual adult and adolescent dose
Analgesic or
Antipyretic
Oral, up to a total of approximately 650 mg of acetaminophen and aspirin (combined) every four to six hours as needed, while symptoms persist. {04} {13}

Antimigraine
Oral, two tablets (500 mg acetaminophen, 500 mg aspirin, and 130 mg caffeine in combination) every six hours while symptoms persist {40}.

Note: This product should not be taken for longer than forty-eight hours for the pain of a migraine headache {40}.



Usual adult and adolescent prescribing limits
Analgesic or

Antipyretic—

For short-term therapy (up to ten days): A total of approximately 4 grams of acetaminophen and aspirin (combined) daily. {04} {13}

For long-term therapy: A total of approximately 2.6 grams of acetaminophen and aspirin (combined) daily, unless chronic treatment with higher doses is prescribed and monitored by a physician. {13}
Antimigraine
8 tablets (2000 mg acetaminophem, 2000 mg aspirin, 520 mg caffeine in combination) in twenty-four hours.


Usual pediatric dose
Analgesic or
Antipyretic
Children up to 9 years of age: Product of suitable strength not available.

Children 9 to 11 years of age: Oral, up to a total of approximately 400 mg of acetaminophen and aspirin (combined) every four hours as needed, while symptoms persist. {13}

Children 11 to 12 years of age: Oral, up to a total of approximately 480 mg of acetaminophen and aspirin (combined) every four hours as needed, while symptoms persist. {13}

Note: Administration of a specific product to a pediatric patient depends upon ability to achieve suitable dosage for the age of the child.
It is recommended that children up to 12 years of age receive no more than five doses in each twenty-four-hour period, unless otherwise directed by a physician, and that a physician be consulted if pain is not relieved within five days, fever within three days, or sore throat within two days. {13}


Antimigraine
Children up to 12 years of age: Use is not recommended {40}.

Children 12 years of age and older: See Usual adult and adolescent dose {40}.


Usual geriatric dose
See Usual adult and adolescent dose . Dosing is based only on the analgesic ingredients.

Note: Because geriatric patients may be more susceptible to adverse renal effects, it may be advisable that they not use acetaminophen and salicylate combinations for longer than five days at a time.


Strength(s) usually available
U.S.—


130 mg of acetaminophen, 260 mg of aspirin, and 16.25 mg of caffeine (OTC) [Goody's Fast Pain Relief{41}{01}]


250 mg of acetaminophen, 250 mg of aspirin, and 65 mg of caffeine (OTC) [Excedrin Extra-Strength Caplets{01}{02}] [Excedrin Extra-Strength Tablets{01}{02}] [Excedrin Migraine{40}]

Canada—
Not commercially available.

Note: In Canada, Excedrin contains only acetaminophen and caffeine. See Acetaminophen (Systemic).


Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F). Store in a well-closed container.

Auxiliary labeling:
   • Avoid alcoholic beverages.
   • Take with food or a full glass of water.


BUFFERED ACETAMINOPHEN, ASPIRIN, AND CAFFEINE TABLETS

Usual adult and adolescent dose
See Acetaminophen, Aspirin, and Caffeine Tablets USP. Dosing is based only on the analgesic ingredients.

Usual adult prescribing limits
See Acetaminophen, Aspirin, and Caffeine Tablets USP. Dosing is based only on the analgesic ingredients.

Usual pediatric dose
See Acetaminophen, Aspirin, and Caffeine Tablets USP. Dosing is based only on the analgesic ingredients.

Usual geriatric dose
See Acetaminophen, Aspirin, and Caffeine Oral Tablets USP. Dosing is based only on the analgesic ingredients.

Strength(s) usually available
U.S.—


125 mg of acetaminophen, 240 mg of aspirin, 32 mg of caffeine, and buffering agents (OTC) [Gelpirin{01}]


160 mg of acetaminophen, 230 mg of aspirin, 33 mg of caffeine, and 60 mg of calcium gluconate (OTC) [Supac{01} (scored )]


194 mg of acetaminophen, 227 mg of aspirin, 33 mg of caffeine, 50 mg of magnesium hydroxide, and 25 mg of aluminum hydroxide (OTC) [Vanquish Caplets{01}{03}]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a well-closed container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Avoid alcoholic beverages.
   • Take with food or a full glass of water.


ACETAMINOPHEN, ASPIRIN, AND SALICYLAMIDE


Oral Dosage Forms

ACETAMINOPHEN, ASPIRIN, SALICYLAMIDE, AND CAFFEINE TABLETS

Usual adult and adolescent dose
Analgesic or
Antipyretic
Oral, up to a total of approximately 325 to 500 mg of acetaminophen, aspirin, and salicylamide (combined) every three hours, 325 to 650 mg of acetaminophen, aspirin, and salicylamide (combined) every four hours, or 650 mg to 1 gram of acetaminophen, aspirin, and salicylamide (combined) every six hours as needed, while symptoms persist. {04} {13}


Note: For patient self-medication, it is recommended that a physician be consulted if pain is not relieved within ten days, fever within three days, or sore throat within two days. {04} {13}
For geriatric patients, it may be advisable that these medications not be used for longer than five days at a time, because such patients may be more susceptible to adverse renal effects.


Usual adult prescribing limits
For short-term therapy (up to ten days)—A total of approximately 4 grams of acetaminophen, aspirin, and salicylamide (combined) daily. {04} {13}

For long-term therapy—A total of approximately 2.6 grams of acetaminophen, aspirin, and salicylamide (combined) daily, unless chronic treatment with higher doses is prescribed and monitored by a physician. {13}

Usual pediatric dose
Analgesic or
Antipyretic
Children up to 9 years of age: Product of suitable strength not available.

Children 9 to 11 years of age: Oral, up to a total of approximately 320 to 400 mg of acetaminophen, aspirin, and salicylamide (combined) every four hours as needed, while symptoms persist. {13}

Children 11 to 12 years of age: Oral, up to a total of approximately 320 to 480 mg of acetaminophen, aspirin, and salicylamide (combined) every four hours as needed, while symptoms persist. {13}


Note: Administration of a specific product to a pediatric patient depends upon ability to achieve suitable dosage for the age of the child.
It is recommended that children up to 12 years of age receive no more than five doses in each twenty-four-hour period, unless otherwise directed by a physician, and that a physician be consulted if pain is not relieved within five days, fever within three days, or sore throat within two days. {13}


Usual geriatric dose
See Usual adult and adolescent dose .

Note: Because geriatric patients may be more susceptible to adverse renal effects, it may be advisable that they not use acetaminophen and salicylate combinations for longer than five days at a time.


Strength(s) usually available
U.S.—


115 mg of acetaminophen, 210 mg of aspirin, 65 mg of salicylamide, and 16 mg of caffeine (OTC) [Saleto{01}]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a well-closed container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Avoid alcoholic beverages.
   • Take with food or a full glass of water.
   • May cause drowsiness.


ACETAMINOPHEN AND SALICYLAMIDE


Oral Dosage Forms

ACETAMINOPHEN, SALICYLAMIDE, AND CAFFEINE CAPSULES

Usual adult and adolescent dose
Analgesic or
Antipyretic
Oral, 500 mg of acetaminophen and salicylamide (combined) every four hours, or 1 gram of acetaminophen and salicylamide (combined) every six hours as needed, while symptoms persist. {04} {13}


Note: For patient self-medication, it is recommended that a physician be consulted if pain is not relieved within ten days, fever within three days, or sore throat within two days. {04} {13}
For geriatric patients, it may be advisable that these medications not be used for longer than five days at a time, because such patients may be more susceptible to adverse renal effects.


Usual adult prescribing limits
For short-term therapy (up to ten days)—A total of approximately 4 grams of acetaminophen and salicylamide (combined) daily. {04} {13}

For long-term therapy—A total of approximately 2.6 grams of acetaminophen and salicylamide (combined) daily, unless chronic treatment with higher doses is prescribed and monitored by a physician. {13}

Usual pediatric dose
Analgesic or
Antipyretic
Children up to 6 years of age: Product of suitable strength not available.

Children 6 to 9 years of age: Oral, up to a total of approximately 320 mg of acetaminophen and salicylamide (combined) every four hours as needed, while symptoms persist. {13}

Children 9 to 11 years of age: Oral, up to a total of approximately 320 to 400 mg of acetaminophen and salicylamide (combined) every four hours as needed, while symptoms persist. {13}

Children 11 to 12 years of age: Oral, up to a total of approximately 320 to 480 mg of acetaminophen and salicylamide (combined) every four hours as needed, while symptoms persist. {13}


Note: Administration of a specific product to a pediatric patient depends upon ability to achieve suitable dosage for the age of the child.
It is recommended that children up to 12 years of age receive no more than five doses in each twenty-four-hour period, unless otherwise directed by a physician, and that a physician be consulted if pain is not relieved within five days, fever within three days, or sore throat within two days. {08}


Usual geriatric dose
See Usual adult and adolescent dose .

Note: Because geriatric patients may be more susceptible to adverse renal effects, it may be advisable that they not use acetaminophen and salicylate combinations for longer than five days at a time.


Strength(s) usually available
U.S.—


226.8 mg of acetaminophen, 97.2 mg of salicylamide, and 32.4 mg of caffeine (OTC) [Rid-A-Pain Compound{01}]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a well-closed container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Avoid alcoholic beverages.
   • Take with food or a full glass of water.
   • May cause drowsiness.



Revised: 07/02/2002



References

Note: All references used in the development and earlier revisions of this monograph have not yet been incorporated into the computer database and, therefore, are not listed below. Citations for information not yet referenced in the monograph will be provided upon request.

  1. Red book 1993. Montvale, NJ: Medical Economics Data; 1993. p.141, 225, 226, 242, 263, 270, 462, 487, 492, 494, 535, 570, 585.
  1. Excedrin Extra-Strength Analgesic Tablets and Caplets (Bristol Myers). In: PDR Physicians' desk reference for nonprescription drugs. 14th ed. 1993. Montvale, NJ: Medical Economics Data; 1993. p.526.
  1. Vanquish Caplets (Sterling Health). In: PDR Physicians' desk reference for nonprescription drugs. 14th ed. 1993. Montvale, NJ: Medical Economics Data; 1993. p. 756.
  1. Tentative final monograph. Notice of proposed rulemaking for internal analgesic, antipyretic, and antirheumatic drug products for over-the-counter human use. Washington, DC: Federal Food and Drug Administration. Federal Register 53 (221), 1988 Nov 16: 46204-58.
  1. Fleeger CA, editor. USAN 1994. USAN and the USP dictionary of drug names. Rockville, MD: The United States Pharmacopeial Convention, Inc, 1993: 17, 59, 110, 591.
  1. Reviewers' responses to Caffeine (Systemic) monograph draft 1986.
  1. FDA OTC Drugs Advisory Panel meeting, 4/8/93.
  1. Panel consensus, Salicylates (Systemic) monograph revision 1983.
  1. Reviewer comment, Caffeine (Systemic) monograph 8/89.
  1. Oei SG, Vosters RPL, van der Hagen NLJ. Fetal arrhythmia caused by excessive intake of caffeine by pregnant women. Br Med J 1989; 298: 568.
  1. Fenster L, Eskenazi B, Windham GC, Swan SH. Caffeine consumption during pregnancy and fetal growth. Am J Public Health 1991 Apr; 81(4): 458-61.
  1. Breast-feeding: a guide for the medical profession. St. Louis: Mosby; 1980. p.157-70.
  1. Reviewers' responses to ballot 11/3/89.
  1. Reviewers' responses to Salicylates monograph revision 1991.
  1. Reviewers' responses to Caffeine (Systemic) monograph revision 1991.
  1. Reviewers' responses to Antacids (Oral-Local) monograph revision 1989.
  1. Reviewers' responses to Sodium Iodide I 123 (Systemic) and Sodium Iodide I 131 (Systemic) monograph revisions 1/17/90.
  1. Adenocard (Fujisawa): In: PDR Physicians' desk reference 48th ed. 1994. Montvale, NJ: Medical Economics Data; 1994. p.958-9.
  1. Panel consensus, Dipyridamole (Systemic) monograph, prepared 1/92.
  1. Sandler DP, Smith JC, Weinberg CR, et al. Analgesic use and chronic renal disease. N Engl J Med 1989 May 11; 320: 1238-43.
  1. Elkind AH. Drug abuse and headache. Med Clin North Am 1991; 75: 717-32.
  1. Greden JG, Viscor BS, Fontaine P, Lubetsky M. Caffeine-withdrawal headache: a clinical profile. Psychosomatics 1980; 21: 411-3, 417-8.
  1. Smith R. Caffeine withdrawal headache. J Clin Pharm Ther 1987; 12: 53-7.
  1. Reviewers' responses to Caffeine (Systemic) monograph revision 1987.
  1. Committee on accident and poison prevention, American Academy of Pediatrics. Salicylates. In: Aronow R, editor. Handbook of common poisonings in children. Evanston, Illinois: American Academy of Pediatrics; 1983. p.126-30.
  1. Dugandzic RM, Tierney MG, Dickinson GE, Dolan MC, McKnight DR. Evaluation of the validity of the Done nomogram in the management of acute salicylate intoxication. Ann Emerg Med 1989 Nov; 18: 1186-90.
  1. Panelist comment.
  1. Panelist comment Salicylates monograph revision 1988.
  1. Larsen JR, Larsen LS. Clinical features and management of poisoning due to phenytoin. Med Toxicol Adverse Drug Exp 1989; 4(4): 229-45.
  1. Hansten PD, Horn JR. Drug interactions. 5th ed. Philadelphia: Lea & Febiger; 1985. p.121-38.
  1. Shinn AF, Shrewsbury RP. EDI: evaluation of drug interactions. 3rd ed. St Louis: Mosby; 1985. p.229-70.
  1. Nation RL, Evans AM, Milne RW. Pharmacokinetic drug interactions with phenytoin (Part I). Clin Pharmacokinet 1990 Jan; 18(1): 37-60.
  1. Dilantin/Phenytoin “Right Dose” Program. Advances in the management of acute seizures in hospitalized patients. Resource Manual. Health Sciences Institute, 1990.
  1. Hoffken G, et al. Pharmacokinetics and bioavailability of ciprofloxacin and ofloxacin: effects of food and antacid intake. Rev Infect Dis 1988; 19 Suppl 1: S138-S139.
  1. Penetrex (Rhone-Poulenc Rorer). In: PDR Physicians' desk reference. 48th ed. 1994. Montvale, NJ: Medical Economics Data Production Company; 1994. p.1861-3.
  1. Panel response to Itraconazole monograph revision 1993.
  1. Shimada J, et al. Effect of antacid on absorption of the quinolone lomefloxacin. Antimicrob Agents Chemother 1992; 36(6): 1219-24.
  1. Nix DE, et al. Inhibition of norfloxacin absorption by antacids. Antimicrob Agents Chemother 1990; 34(3): 432-5.
  1. Flor S, et al. Effects of magnesium-aluminum hydroxide and calcium carbonate antacids on bioavailability of ofloxacin. Antimicrob Agents Chemother 1990; 34(12): 2436-8.
  1. Excedrin Migraine package insert (Bristol-Myers Squibb—US), New 3/98, Rec 9/98.
  1. Red book 2002 Online. Montvale, NJ: Medical Economics Data; 6/27/2002
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