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Pentazocine and Acetaminophen
(pen TAZ oh seen & a seet a MIN oh fen)
- Acetaminophen and Pentazocine
- Pentazocine Hydrochloride and Acetaminophen
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Tablet: Pentazocine 25 mg and acetaminophen 650 mg [DSC]
- Analgesic Combination (Opioid)
- Analgesic, Opioid
- Analgesic, Opioid Partial Agonist
Pentazocine: Agonist of kappa opiate receptors and partial agonist of mu opiate receptors in the CNS, causing inhibition of ascending pain pathways, altering the perception of and response to pain; produces analgesia, respiratory depression and sedation similar to opioids
Acetaminophen: Although not fully elucidated, the analgesic effects are believed to be due to activation of descending serotonergic inhibitory pathways in the CNS. Interactions with other nociceptive systems may be involved as well (Smith 2009). Antipyresis is produced from inhibition of the hypothalamic heat-regulating center.
Use: Labeled Indications
Relief of mild-to-moderate pain
Hypersensitivity to pentazocine, acetaminophen, or any component of the formulation; hypersensitivity to sulfites (contains metabisulfite)
Note: Maximum daily intake of acetaminophen from all sources should not exceed 4 g.
Analgesic: Oral: One caplet (pentazocine 25 mg/acetaminophen 650 mg) every 4 hours as needed (maximum: 6 caplets/day)
Refer to adult dosing. Use with caution; may be more sensitive to analgesic and sedative effects.
Analgesic: Oral: Children ≥12 years: Refer to adult dosing.
Dosing: Renal Impairment
No dosage adjustment provided in manufacturer’s labeling. Use with caution.
Dosing: Hepatic Impairment
No dosage adjustment provided in manufacturer’s labeling. However, dosage adjustment may be necessary due to decreased metabolism and predisposition to adverse effects. Use with caution.
Store at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).
Alvimopan: Opioid Analgesics may enhance the adverse/toxic effect of Alvimopan. This is most notable for patients receiving long-term (i.e., more than 7 days) opiates prior to alvimopan initiation. Management: Alvimopan is contraindicated in patients receiving therapeutic doses of opioids for more than 7 consecutive days immediately prior to alvimopan initiation. Consider therapy modification
Amphetamines: May enhance the analgesic effect of Opioid Analgesics. Monitor therapy
Anticholinergic Agents: May enhance the adverse/toxic effect of Opioid Analgesics. Specifically, the risk for constipation and urinary retention may be increased with this combination. Monitor therapy
Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
Buprenorphine: Opioids (Mixed Agonist / Antagonist) may diminish the therapeutic effect of Buprenorphine. This combination may also induce opioid withdrawal. Avoid combination
Busulfan: Acetaminophen may increase the serum concentration of Busulfan. Monitor therapy
Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Consider therapy modification
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Cholestyramine Resin: May decrease the absorption of Acetaminophen. Effect is minimal if cholestyramine is administered 1 hour after acetaminophen. Consider therapy modification
CNS Depressants: May enhance the CNS depressant effect of Opioid Analgesics. Management: Avoid concomitant use of opioid analgesics and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification
Dapsone (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy
Dasatinib: Acetaminophen may enhance the hepatotoxic effect of Dasatinib. Dasatinib may increase the serum concentration of Acetaminophen. Consider therapy modification
Desmopressin: Opioid Analgesics may enhance the adverse/toxic effect of Desmopressin. Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Diuretics: Opioid Analgesics may enhance the adverse/toxic effect of Diuretics. Opioid Analgesics may diminish the therapeutic effect of Diuretics. Monitor therapy
Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification
Eluxadoline: Opioid Analgesics may enhance the constipating effect of Eluxadoline. Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification
Gastrointestinal Agents (Prokinetic): Opioid Analgesics may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Monitor therapy
Imatinib: Acetaminophen may enhance the hepatotoxic effect of Imatinib. Monitor therapy
Isoniazid: May enhance the adverse/toxic effect of Acetaminophen. Monitor therapy
Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification
MetyraPONE: May increase the serum concentration of Acetaminophen. More importantly, by inhibiting the conjugative metabolism of acetaminophen, metyrapone may shift the metabolism towards the oxidative route that produces a hepatotoxic metabolite. Monitor therapy
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy
Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Mipomersen: Acetaminophen may enhance the hepatotoxic effect of Mipomersen. Monitor therapy
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Nalmefene: May diminish the therapeutic effect of Opioid Analgesics. Management: Avoid the concomitant use of nalmefene and opioid analgesics. Discontinue nalmefene 1 week prior to any anticipated use of opioid analgesics. If combined, larger doses of opioid analgesics will likely be required. Consider therapy modification
Naltrexone: May diminish the therapeutic effect of Opioid Analgesics. Management: Seek therapeutic alternatives to opioids. See full drug interaction monograph for detailed recommendations. Consider therapy modification
Nitric Oxide: May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when nitric oxide is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine. Monitor therapy
Opioid Analgesics: Opioids (Mixed Agonist / Antagonist) may diminish the analgesic effect of Opioid Analgesics. Management: Seek alternatives to mixed agonist/antagonist opioids in patients receiving pure opioid agonists, and monitor for symptoms of therapeutic failure/high dose requirements (or withdrawal in opioid-dependent patients) if patients receive these combinations. Exceptions: Buprenorphine; Butorphanol; Meptazinol; Nalbuphine; Pentazocine. Avoid combination
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination
Pegvisomant: Opioid Analgesics may diminish the therapeutic effect of Pegvisomant. Monitor therapy
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification
Phenylephrine (Systemic): Acetaminophen may increase the serum concentration of Phenylephrine (Systemic). Monitor therapy
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Monitor therapy
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy
Prilocaine: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Prilocaine. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Management: Monitor patients for signs of methemoglobinemia (e.g., hypoxia, cyanosis) when prilocaine is used in combination with other agents associated with development of methemoglobinemia. Avoid lidocaine/prilocaine in infants receiving such agents. Monitor therapy
Probenecid: May increase the serum concentration of Acetaminophen. Probenecid may also limit the formation of at least one major non-toxic metabolite, possibly increasing the potential for formation of the toxic NAPQI metabolite. Consider therapy modification
Ramosetron: Opioid Analgesics may enhance the constipating effect of Ramosetron. Monitor therapy
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy
Selective Serotonin Reuptake Inhibitors: CNS Depressants may enhance the adverse/toxic effect of Selective Serotonin Reuptake Inhibitors. Specifically, the risk of psychomotor impairment may be enhanced. Monitor therapy
Serotonin Modulators: Opioid Analgesics may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Exceptions: Nicergoline. Monitor therapy
Sodium Nitrite: Methemoglobinemia Associated Agents may enhance the adverse/toxic effect of Sodium Nitrite. Combinations of these agents may increase the likelihood of significant methemoglobinemia. Monitor therapy
Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification
SORAfenib: Acetaminophen may enhance the hepatotoxic effect of SORAfenib. SORAfenib may increase the serum concentration of Acetaminophen. Consider therapy modification
Succinylcholine: May enhance the bradycardic effect of Opioid Analgesics. Monitor therapy
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification
Tetracaine (Topical): May enhance the adverse/toxic effect of Methemoglobinemia Associated Agents. Monitor therapy
Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination
Vitamin K Antagonists (eg, warfarin): Acetaminophen may enhance the anticoagulant effect of Vitamin K Antagonists. This appears most likely with daily acetaminophen doses exceeding 1.3 or 2 g/day for multiple consecutive days. Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification
See individual agents.
Adverse reactions attributed to pentazocine 50 mg. Frequency not defined. See Acetaminophen monograph for acetaminophen-related reactions.
Cardiovascular: Circulatory depression, facial edema, flushing, hypertension, hypotension, syncope, tachycardia
Central nervous system: Chills, confusion, depression, disorientation, dizziness, drowsiness, drug dependence (physical and physological), euphoria, excitement, hallucination, headache, increased intracranial pressure, insomnia, irritability, nightmares, paresthesia, sedation, seizure, withdrawal syndrome
Dermatologic: Dermatitis, diaphoresis, erythema multiforme, pruritus, skin rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
Gastrointestinal: Abdominal distress, anorexia, biliary colic, constipation, diarrhea, nausea, vomiting, xerostomia
Genitourinary: Urinary retention
Hematologic & oncologic: Agranulocytosis, decreased white blood cell count, eosinophilia
Neuromuscular & skeletal: Tremor, weakness
Ophthalmic: Blurred vision, miosis
Respiratory: Respiratory depression
Postmarketing and/or case reports: Hypogonadism (Brennan, 2013; Debono, 2011)
Concerns related to adverse effects:
• Adrenal insufficiency: Use with caution in patients with adrenal insufficiency, including Addison's disease. Long-term opioid use may cause secondary hypogonadism, which may lead to sexual dysfunction, infertility, mood disorders, and osteoporosis (Brennan, 2013).
• CNS effects: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving). Confusion, disorientation, and visual hallucinations have occurred in some patients, but usually clears within a few hours; observe patients closely.
• Hepatotoxicity: [US Boxed Warning]: Acetaminophen may cause severe hepatotoxicity, potentially requiring liver transplant or resulting in death; hepatotoxicity is usually associated with excessive acetaminophen intake (>4 g/day). Risk is increased with alcohol use, pre-existing liver disease, and intake of more than one source of acetaminophen-containing medications. Chronic daily dosing in adults has also resulted in liver damage in some patients.
• Hypersensitivity/anaphylactic reactions: Hypersensitivity and anaphylactic reactions have been reported with acetaminophen use; discontinue immediately if symptoms of allergic or hypersensitivity reactions occur.
• Skin reactions: Rarely, acetaminophen may cause serious and potentially fatal skin reactions such as acute generalized exanthematous pustulosis, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Discontinue treatment if severe skin reactions develop.
• Abdominal conditions: May obscure diagnosis or clinical course of patients with acute abdominal conditions.
• Adrenal insufficiency: Use with caution in patients with adrenal insufficiency, including Addison disease.
• Biliary tract impairment: Use pentazocine with caution in patients with biliary tract dysfunction, including acute pancreatitis; may cause constriction of sphincter of Oddi.
• Bowel disease: Use with caution in patients with inflammatory or obstructive bowel disease.
• CNS depression/coma: Avoid use in patients with CNS depression or coma as these patients are susceptible to intracranial effects of CO2 retention.
• Drug abuse: Use opioids for chronic pain with caution in patients at increased risk for misuse; factors associated with increased risk include previous substance use disorder, younger age, concomitant depression (major), and psychotropic medication use. Consider offering naloxone prescriptions in patients with factors associated with an increased risk for overdose, such as history of overdose or substance use disorder, higher opioid dosages (≥50 morphine milligram equivalents/day orally), and concomitant benzodiazepine use (Dowell [CDC 2016]).
• Ethanol use: Use with caution in patients with alcoholic liver disease; consuming ≥3 alcoholic drinks/day may increase the risk of liver damage.
• G6PD deficiency: Use with caution in patients with known G6PD deficiency.
• Head trauma: Use with extreme caution in patients with head injury, intracranial lesions, or elevated intracranial pressure; exaggerated elevation of ICP may occur.
• Hepatic impairment: Use with caution in patients with hepatic dysfunction.
• Mental health conditions: Use opioids with caution for chronic pain in patients with mental health conditions (eg, depression, anxiety disorders, post-traumatic stress disorder) due to increased risk for opioid use disorder and overdose; more frequent monitoring is recommended (Dowell [CDC 2016]).
• Myocardial infarction (MI): Use with caution in patients with acute MI or MI with nausea/vomiting; hypertension may occur with pentazocine use.
• Porphyria: Use with caution in patients with a history of porphyria; may exacerbate condition.
• Prostatic hyperplasia/urinary stricture: Use with caution in patients with prostatic hyperplasia and/or urinary stricture, especially when combined with medications that have anticholinergic effects.
• Renal impairment: Use with caution in patients with renal dysfunction.
• Respiratory disease: Use with caution in patients with pre-existing respiratory compromise (hypoxia and/or hypercapnia), COPD or other obstructive pulmonary disease, and kyphoscoliosis or other skeletal disorder which may alter respiratory function; critical respiratory depression may occur, even at therapeutic dosages.
• Seizures: Effects may be potentiated when used with other sedatives, including opioids or ethanol.
• Sleep-disordered breathing: Use opioids with caution for chronic pain and titrate dosage cautiously in patients with risk factors for sleep-disordered breathing, including HF and obesity. Avoid opioids in patients with moderate to severe sleep-disordered breathing (Dowell [CDC 2016]).
• Thyroid dysfunction: Use with caution in patients with hypothyroidism.
Concurrent drug therapy issues:
• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
• Sedatives: Effects may be potentiated when used with other sedatives, including opioids or ethanol. In the setting of chronic pain, avoid prescribing opioids and benzodiazepines concurrently whenever possible; epidemiologic studies suggest there is an increased risk for potentially fatal overdose with concurrent use (Dowell [CDC 2016]).
• Debilitated patients: Use with caution in debilitated patients; there is a greater potential for critical respiratory depression, even at therapeutic dosages.
• Elderly: Use with caution in the elderly; may be more sensitive to adverse effects. Use opioids for chronic pain with caution in this age group; monitor closely due to an increased potential for risks, including certain risks such as falls/fracture, cognitive impairment, and constipation. Clearance may also be reduced in older adults (with or without renal impairment) resulting in a narrow therapeutic window and increasing the risk for respiratory depression or overdose (Dowell [CDC 2016]).
• Neonates: Neonatal withdrawal syndrome: After chronic maternal exposure to opioids, neonatal withdrawal syndrome may occur in the newborn; monitor neonate closely. Signs and symptoms include irritability, hyperactivity and abnormal sleep pattern, high pitched cry, tremor, vomiting, diarrhea and failure to gain weight. Onset, duration and severity depend on the drug used, duration of use, maternal dose, and rate of drug elimination by the newborn. Opioid withdrawal syndrome in the neonate, unlike in adults, may be life-threatening and should be treated according to protocols developed by neonatology experts.
• Smokers: Pentazocine clearance may be increased.
Dosage form specific issues:
• Sodium metabisulfite: May contain sodium metabisulfite; may cause allergic-type reactions including anaphylaxis.
• Appropriate use: Chronic pain (outside of end-of-life or palliative care, active cancer treatment, sickle cell disease, or medication-assisted treatment for opioid use disorder) in outpatient setting in adults: Opioids should not be used as first-line therapy for chronic pain management (pain >3-month duration or beyond time of normal tissue healing) due to limited short-term benefits, undetermined long-term benefits, and association with serious risks (eg, overdose, MI, auto accidents, risk of developing opioid use disorder). Preferred management includes nonpharmacologic therapy and nonopioid therapy (eg, NSAIDs, acetaminophen, certain anticonvulsants and antidepressants). If opioid therapy is initiated, it should be combined with nonpharmacologic and non-opioid therapy, as appropriate. Prior to initiation, known risks of opioid therapy should be discussed and realistic treatment goals for pain/function should be established, including consideration for discontinuation if benefits do not outweigh risks. Therapy should be continued only if clinically meaningful improvement in pain/function outweighs risks. Therapy should be initiated at the lowest effective dosage using immediate-release opioids (instead of extended-release/long-acting opioids). Risk associated with use increases with higher opioid dosages. Risks and benefits should be re-evaluated when increasing dosage to ≥50 morphine milligram equivalents (MME)/day orally; dosages ≥90 MME/day orally should be avoided unless carefully justified (Dowell [CDC 2016]).
• Dosage limit: Limit acetaminophen dose from all sources (prescription and OTC) to <4 g/day.
• Withdrawal: Concurrent use of agonist/antagonist analgesics may precipitate withdrawal symptoms and/or reduced analgesic efficacy in patients following prolonged therapy with mu opioid agonists. Abrupt discontinuation following prolonged use may also lead to withdrawal symptoms; taper dose to decrease risk of withdrawal symptoms.
Signs or symptoms of hypogonadism or hypoadrenalism (Brennan 2013).
Alternate recommendations: Chronic pain (long-term therapy outside of end-of-life or palliative care, active cancer treatment, sickle cell disease, or medication-assisted treatment for opioid use disorder): Evaluate benefits/risks of opioid therapy within 1 to 4 weeks of treatment initiation and with dose increases. Re-evaluate benefits/risks every 3 months during therapy or more frequently in patients at increased risk of overdose or opioid use disorder. Urine drug testing is recommended prior to initiation and re-checking should be considered at least yearly (includes controlled prescription medications and illicit drugs of abuse). State prescription drug monitoring program (PDMP) data should be reviewed by clinicians prior to initiation and periodically during therapy (frequency ranging from every prescription to every 3 months) (Dowell [CDC 2016]).
Pregnancy Risk Factor
See individual agents.
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience fatigue, nausea, or sweating a lot. Have patient report immediately to prescriber signs of liver problems (dark urine, feeling tired, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or yellow skin or eyes), severe dizziness, passing out, difficulty breathing, slow breathing, shallow breathing, illogical thinking, severe nausea, vomiting, severe constipation, loss of strength and energy, tachycardia, chills, pharyngitis, hallucinations, mood changes, seizures, severe headache, tremors, insomnia, difficult urination, vision changes, or signs of Stevens-Johnson syndrome/toxic epidermal necrolysis (red, swollen, blistered, or peeling skin [with or without fever]; red or irritated eyes; or sores in mouth, throat, nose, or eyes) (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
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