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Interactions between Loxapine and Zflex

1 drug interaction and 55 additional warnings found for the following 2 drugs:

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Drug interactions

Moderate drug interactions

Moderate:

loxapine phenyltoloxamine

Applies to: loxapine and Zflex (acetaminophen / phenyltoloxamine)
Monitor

Agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) may have additive effects when used in combination. Excessive parasympatholytic effects may result in paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention, and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy, and seizures. Central nervous system-depressant effects may also be additively or synergistically increased when these agents are combined, especially in elderly or debilitated patients. Use of neuroleptics in combination with other neuroleptics or anticholinergic agents may increase the risk of tardive dyskinesia. In addition, some neuroleptics and tricyclic antidepressants may cause prolongation of the QT interval and theoretically, concurrent use of two or more drugs that can cause QT interval prolongation may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death.

Management

Caution is advised when agents with anticholinergic properties are combined, particularly in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A reduction in anticholinergic dosages may be necessary if excessive adverse effects develop.

References (15)
  1. Stadnyk AN, Glezos JD (1983) "Drug-induced heat stroke." Can Med Assoc J, 128, p. 957-9
  2. Zelman S, Guillan R (1970) "Heat stroke in phenothiazine-treated patients: a report of three fatalities." Am J Psychiatry, 126, p. 1787-90
  3. Mann SC, Boger WP (1978) "Psychotropic drugs, summer heat and humidity, and hyperplexia: a danger restated." Am J Psychiatry, 135, p. 1097-100
  4. Warnes H, Lehmann HE, Ban TA (1967) "Adynamic ileus during psychoactive medication: a report of three fatal and five severe cases." Can Med Assoc J, 96, p. 1112-3
  5. Gershon S, Neubauer H, Sundland DM (1965) "Interaction between some anticholinergic agents and phenothiazines." Clin Pharmacol Ther, 6, p. 749-56
  6. Sarnquist F, Larson CP Jr (1973) "Drug-induced heat stroke." Anesthesiology, 39, p. 348-50
  7. Johnson AL, Hollister LE, Berger PA (1981) "The anticholinergic intoxication syndrome: diagnosis and treatment." J Clin Psychiatry, 42, p. 313-7
  8. Lee BS (1986) "Possibility of hyperpyrexia with antipsychotic and anticholinergic drugs." J Clin Psychiatry, 47, p. 571
  9. Forester D (1978) "Fatal drug-induced heat stroke." JACEP, 7, p. 243-4
  10. Moreau A, Jones BD, Banno V (1986) "Chronic central anticholinergic toxicity in manic depressive illness mimicking dementia." Can J Psychiatry, 31, p. 339-41
  11. Hvizdos AJ, Bennett JA, Wells BG, Rappaport KB, Mendel SA (1983) "Anticholinergic psychosis in a patient receiving usual doses of haloperidol." Clin Pharm, 2, p. 174-8
  12. Cohen MA, Alfonso CA, Mosquera M (1994) "Development of urinary retention during treatment with clozapine and meclizine [published erratum appears in Am J Psychiatry 1994 Jun;151(6):952]." Am J Psychiatry, 151, p. 619-20
  13. (2001) "Product Information. Cogentin (benztropine)." Merck & Co., Inc
  14. Kulik AV, Wilbur R (1982) "Delirium and stereotypy from anticholinergic antiparkinson drugs." Prog Neuropsychopharmacol Biol Psychiatry, 6, p. 75-82
  15. (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories

Food/lifestyle interactions

Major food/lifestyle interactions

Major:

acetaminophen Food/Lifestyle

Applies to: Zflex (acetaminophen / phenyltoloxamine)
Generally avoid

Chronic, excessive consumption of alcohol may increase the risk of acetaminophen-induced hepatotoxicity, which has included rare cases of fatal hepatitis and frank hepatic failure requiring liver transplantation. The proposed mechanism is induction of hepatic microsomal enzymes during chronic alcohol use, which may result in accelerated metabolism of acetaminophen and increased production of potentially hepatotoxic metabolites.

Management

In general, chronic alcoholics should avoid regular or excessive use of acetaminophen. Alternative analgesic/antipyretic therapy may be appropriate in patients who consume three or more alcoholic drinks per day.

References (1)
  1. (2022) "Product Information. Acetaminophen (acetaminophen)." Camber Pharmaceuticals, Inc

Moderate food/lifestyle interactions

Moderate:

loxapine Food/Lifestyle

Applies to: loxapine
Generally avoid

Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

Management

Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References (4)
  1. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
  3. (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
  4. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.
Moderate:

phenyltoloxamine Food/Lifestyle

Applies to: Zflex (acetaminophen / phenyltoloxamine)
Generally avoid

Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

Management

Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References (4)
  1. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
  3. (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
  4. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.

Disease interactions

52 potential interactions Applies to: 38 conditions, including Asthma, COPD, Seizures, Diarrhea, and Breast Cancer.

Acute Alcohol Intoxication

Major:

loxapine

Loxapine has a major potential interaction with Acute Alcohol Intoxication.

The use of most miscellaneous antipsychotics is contraindicated in patients with severe central nervous system depression or comatose states from any cause (e.g., lesion, disease, drug or alcohol induced).

Alcoholism

Major:

loxapine

Loxapine has a major potential interaction with Alcoholism.

Antipsychotics can lower the seizure threshold and trigger seizures in a dose-dependent manner. Seizures have been reported in patients receiving antipsychotic therapy and may occur in epileptic patients even with maintenance of routine anticonvulsant treatment. Therapy with antipsychotics should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism. High dosages should be avoided if possible.

Major:

loxapine

Loxapine has a major potential interaction with Alcoholism.

The use of neuroleptic agents is contraindicated in patients with acute alcohol intoxication exhibiting depressed vital signs. The central nervous system depressant effects of neuroleptic agents may be additive with those of alcohol. Severe respiratory depression and respiratory arrest may occur. Therapy with neuroleptic agents should be administered cautiously in patients who might be prone to acute alcohol intake.

Major:

Zflex

The acetaminophen in Zflex has a major potential interaction with Alcoholism.

Chronic alcohol abusers may be at increased risk of hepatotoxicity during treatment with acetaminophen (APAP). Severe liver injury, including cases of acute liver failure resulting in liver transplant and death, has been reported in patients using acetaminophen. Therapy with acetaminophen should be administered cautiously, if at all, in patients who consume three or more alcoholic drinks a day. In general, patients should avoid drinking alcohol while taking acetaminophen-containing medications. Patients should be warned not to exceed the maximum recommended total daily dosage of acetaminophen (4 g/day in adults and children 12 years of age or older), and to read all prescription and over-the-counter medication labels to ensure they are not taking multiple acetaminophen-containing products, or check with a healthcare professional if they are unsure. They should also be advised to seek medical attention if they experience signs and symptoms of liver injury such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, and jaundice.

Moderate:

loxapine

Loxapine has a moderate potential interaction with Alcoholism.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Altered Consciousness

Major:

loxapine

Loxapine has a major potential interaction with Altered Consciousness.

The use of most miscellaneous antipsychotics is contraindicated in patients with severe central nervous system depression or comatose states from any cause (e.g., lesion, disease, drug or alcohol induced).

Major:

loxapine

Loxapine has a major potential interaction with Altered Consciousness.

The use of neuroleptic agents is contraindicated in comatose patients and patients with severe central nervous system depression. Neuroleptic agents may potentiate the CNS and respiratory depression in these patients.

Asthma

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Asthma.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Brain Tumor

Moderate:

loxapine

Loxapine has a moderate potential interaction with Brain Tumor.

Some antipsychotics such as loxapine and molindone have antiemetic effects and may mask signs of overdosage of toxic drugs, and may obscure conditions such as intestinal obstruction and brain tumor.

Breast Cancer

Moderate:

loxapine

Loxapine has a moderate potential interaction with Breast Cancer.

Antipsychotic drugs can elevate serum prolactin concentrations, and this elevation persists during chronic administration. This should be considered if therapy will be prescribed in patients with previously detected breast cancer as one-third of human breast cancers are prolactin-dependent in vitro. Associated disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported. Appropriate laboratory testing and follow-up is advised.

Moderate:

loxapine

Loxapine has a moderate potential interaction with Breast Cancer.

The chronic use of neuroleptic agents can cause persistent elevations in prolactin levels due to antagonism of dopamine D2 receptors. Based on in vitro data, approximately one-third of human breast cancers are thought to be prolactin-dependent. The clinical significance of this observation with respect to long-term neuroleptic therapy is unknown. Chronic administration of neuroleptic drugs has been associated with mammary tumorigenesis in rodent studies but not in human clinical or epidemiologic studies. Until further data are available, therapy with neuroleptic agents should be administered cautiously in patients with a previously detected breast cancer. Caution is also advised in patients with preexisting hyperprolactinemia. Hyperprolactinemia may suppress hypothalamic gonadotrophin releasing hormone (GnRH), resulting in reduced pituitary gonadotropin secretion. This, in turn, may inhibit reproductive function by impairing gonadal steroidogenesis in both female and male patients. Galactorrhea, amenorrhea, gynecomastia, and impotence have been reported in patients receiving prolactin-elevating compounds; however, the clinical significance of elevated serum prolactin levels is unknown for most patients. Long-standing hyperprolactinemia when associated with hypogonadism may lead to decreased bone density in both female and male patients.

Cardiovascular Conditions and Disorders

Moderate:

loxapine

Loxapine has a moderate potential interaction with Cardiovascular Conditions and Disorders.

Loxapine should be administered cautiously to patients with cardiovascular disease as increased pulse rates and transient hypotension have been reported. In the presence of severe hypotension requiring vasopressor therapy, the preferred drugs may be norepinephrine and angiotensin, as usual doses of epinephrine may be ineffective as loxapine inhibits its vasopressor effect.

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Cardiovascular Conditions and Disorders.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Central Nervous System Disorders

Major:

loxapine

Loxapine has a major potential interaction with Central Nervous System Disorders.

Antipsychotics can lower the seizure threshold and trigger seizures in a dose-dependent manner. Seizures have been reported in patients receiving antipsychotic therapy and may occur in epileptic patients even with maintenance of routine anticonvulsant treatment. Therapy with antipsychotics should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism. High dosages should be avoided if possible.

Cerebrovascular Insufficiency

Major:

loxapine

Loxapine has a major potential interaction with Cerebrovascular Insufficiency.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

COPD

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with COPD.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Dehydration

Major:

Zflex

The acetaminophen in Zflex has a major potential interaction with Dehydration.

Acetaminophen is contraindicated in patients with severe hepatic impairment or severe active liver disease. Patients with hepatic impairment may be at increased risk of toxicity. Severe liver injury, including cases of acute liver failure and death, have been reported in patients using this drug. Clinical monitoring of hepatic function is recommended. Caution is advised if using acetaminophen in patients with chronic malnutrition or severe hypovolemia. Instruct patients to avoid drinking alcohol while taking acetaminophen-containing medications. Patients should be warned not to exceed the maximum recommended total daily dosage of acetaminophen (4 g/day in adults and children 12 years of age or older), and to read all prescription and over-the-counter medication labels to ensure they are not taking multiple acetaminophen-containing products, or check with a healthcare professional if they are unsure.

Moderate:

loxapine

Loxapine has a moderate potential interaction with Dehydration.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

Dementia

Major:

loxapine

Loxapine has a major potential interaction with Dementia.

Elderly patients with dementia- related psychosis treated with antipsychotic drugs are at increased risk of death. Most of these drugs are not approved for the treatment of patients with dementia- related psychosis.

Major:

loxapine

Loxapine has a major potential interaction with Dementia.

Antipsychotic drugs are not approved for the treatment of patients with dementia-related psychosis. Older patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death; although the causes were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. A causal relationship with antipsychotic use has not been established. In controlled trials in older patients with dementia-related psychosis, patients randomized to risperidone, aripiprazole, and olanzapine had higher incidence of cerebrovascular adverse events (e.g., stroke, transient ischemic attack), including fatalities, compared to patients treated with placebo.

Diarrhea

Moderate:

loxapine

Loxapine has a moderate potential interaction with Diarrhea.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

Gastrointestinal Obstruction

Moderate:

loxapine

Loxapine has a moderate potential interaction with Gastrointestinal Obstruction.

Most neuroleptic agents have anticholinergic activity, to which elderly patients are particularly sensitive. Clozapine and low- potency agents such as chlorpromazine and thioridazine tend to exhibit the greatest degree of anticholinergic effects in the class, while haloperidol as well as the newer, atypical agents like quetiapine, risperidone and ziprasidone have generally been associated with very low frequencies of anticholinergic adverse effects. Therapy with neuroleptic agents should be administered cautiously in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders.

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Gastrointestinal Obstruction.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Glaucoma, Narrow Angle

Moderate:

loxapine

Loxapine has a moderate potential interaction with Glaucoma, Narrow Angle.

Because of the possible anticholinergic action, loxapine should be used cautiously in patients with glaucoma or with a tendency to urinary retention, particularly if used with any other drugs with anticholinergic effect (e.g., antiparkinson medication).

Glaucoma/Intraocular Hypertension

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Glaucoma/Intraocular Hypertension.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Head Injury

Moderate:

loxapine

Loxapine has a moderate potential interaction with Head Injury.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Heart Disease

Major:

loxapine

Loxapine has a major potential interaction with Heart Disease.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

History - Cerebrovascular Disease

Major:

loxapine

Loxapine has a major potential interaction with History - Cerebrovascular Disease.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

History - Myocardial Infarction

Major:

loxapine

Loxapine has a major potential interaction with History - Myocardial Infarction.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

Hyperprolactinemia

Moderate:

loxapine

Loxapine has a moderate potential interaction with Hyperprolactinemia.

Antipsychotic drugs can elevate serum prolactin concentrations, and this elevation persists during chronic administration. This should be considered if therapy will be prescribed in patients with previously detected breast cancer as one-third of human breast cancers are prolactin-dependent in vitro. Associated disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported. Appropriate laboratory testing and follow-up is advised.

Moderate:

loxapine

Loxapine has a moderate potential interaction with Hyperprolactinemia.

The chronic use of neuroleptic agents can cause persistent elevations in prolactin levels due to antagonism of dopamine D2 receptors. Based on in vitro data, approximately one-third of human breast cancers are thought to be prolactin-dependent. The clinical significance of this observation with respect to long-term neuroleptic therapy is unknown. Chronic administration of neuroleptic drugs has been associated with mammary tumorigenesis in rodent studies but not in human clinical or epidemiologic studies. Until further data are available, therapy with neuroleptic agents should be administered cautiously in patients with a previously detected breast cancer. Caution is also advised in patients with preexisting hyperprolactinemia. Hyperprolactinemia may suppress hypothalamic gonadotrophin releasing hormone (GnRH), resulting in reduced pituitary gonadotropin secretion. This, in turn, may inhibit reproductive function by impairing gonadal steroidogenesis in both female and male patients. Galactorrhea, amenorrhea, gynecomastia, and impotence have been reported in patients receiving prolactin-elevating compounds; however, the clinical significance of elevated serum prolactin levels is unknown for most patients. Long-standing hyperprolactinemia when associated with hypogonadism may lead to decreased bone density in both female and male patients.

Hyperthyroidism

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Hyperthyroidism.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Hypotension

Major:

loxapine

Loxapine has a major potential interaction with Hypotension.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Hypotension.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Intestinal Obstruction

Moderate:

loxapine

Loxapine has a moderate potential interaction with Intestinal Obstruction.

Some antipsychotics such as loxapine and molindone have antiemetic effects and may mask signs of overdosage of toxic drugs, and may obscure conditions such as intestinal obstruction and brain tumor.

Liver Disease

Major:

Zflex

The acetaminophen in Zflex has a major potential interaction with Liver Disease.

Acetaminophen is contraindicated in patients with severe hepatic impairment or severe active liver disease. Patients with hepatic impairment may be at increased risk of toxicity. Severe liver injury, including cases of acute liver failure and death, have been reported in patients using this drug. Clinical monitoring of hepatic function is recommended. Caution is advised if using acetaminophen in patients with chronic malnutrition or severe hypovolemia. Instruct patients to avoid drinking alcohol while taking acetaminophen-containing medications. Patients should be warned not to exceed the maximum recommended total daily dosage of acetaminophen (4 g/day in adults and children 12 years of age or older), and to read all prescription and over-the-counter medication labels to ensure they are not taking multiple acetaminophen-containing products, or check with a healthcare professional if they are unsure.

Moderate:

loxapine

Loxapine has a moderate potential interaction with Liver Disease.

Most neuroleptic agents are extensively metabolized by the liver. The plasma concentrations of these agents may be increased and the half-lives prolonged in patients with impaired hepatic function. Therapy with neuroleptic agents should be administered cautiously in patients with significant liver disease. Lower initial dosages and slower titration may be appropriate.

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Liver Disease.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Malnourishment

Major:

Zflex

The acetaminophen in Zflex has a major potential interaction with Malnourishment.

Acetaminophen is contraindicated in patients with severe hepatic impairment or severe active liver disease. Patients with hepatic impairment may be at increased risk of toxicity. Severe liver injury, including cases of acute liver failure and death, have been reported in patients using this drug. Clinical monitoring of hepatic function is recommended. Caution is advised if using acetaminophen in patients with chronic malnutrition or severe hypovolemia. Instruct patients to avoid drinking alcohol while taking acetaminophen-containing medications. Patients should be warned not to exceed the maximum recommended total daily dosage of acetaminophen (4 g/day in adults and children 12 years of age or older), and to read all prescription and over-the-counter medication labels to ensure they are not taking multiple acetaminophen-containing products, or check with a healthcare professional if they are unsure.

Neuroleptic Malignant Syndrome

Major:

loxapine

Loxapine has a major potential interaction with Neuroleptic Malignant Syndrome.

The central dopaminergic blocking effects of neuroleptic agents may precipitate or aggravate a potentially fatal symptom complex known as neuroleptic malignant syndrome (NMS). NMS is observed most frequently when high-potency agents like haloperidol are administered intramuscularly, but may occur with any neuroleptic agent given for any length of time. Clinical manifestations of NMS include hyperpyrexia, muscle rigidity, altered mental status and autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac arrhythmias). Additional signs may include elevated creatine phosphokinase, myoglobinuria, and acute renal failure. Neuroleptic agents should not be given to patients with active NMS and should be immediately discontinued if currently being administered in such patients. In patients with a history of NMS, introduction or reintroduction of neuroleptic agents should be carefully considered, since NMS may recur.

Major:

loxapine

Loxapine has a major potential interaction with Neuroleptic Malignant Syndrome.

Neuroleptic Malignant Syndrome (NMS), a potentially fatal symptom complex, has been reported in association with the use of antipsychotic drugs. The diagnostic evaluation is complicated and the management requires immediate discontinuation of the antipsychotic therapy and intensive symptomatic treatment and medical monitoring. If a patient that has recovered from NMS requires antipsychotic drug treatment again, the reintroduction of therapy should be carefully considered as NMS recurrences have been reported.

Neutropenia

Moderate:

loxapine

Loxapine has a moderate potential interaction with Neutropenia.

The use of antipsychotics has been associated with events of leukopenia, neutropenia and agranulocytosis. Possible risk factors include preexisting low white blood cell count, and history of drug induced leukopenia/neutropenia. Patients with these risk factors should have complete blood count monitored frequently during the first few months of therapy. Patients should also be monitored for any signs or symptoms of infection. Treatment should be discontinued in any patient who develops a sore throat, fever, stomatitis, or other signs of infection along with a low WBC count or severe neutropenia (ANC < 1000/mm3).

Parkinsonism

Moderate:

loxapine

Loxapine has a moderate potential interaction with Parkinsonism.

The use of neuroleptic agents is associated with pseudo-parkinsonian symptoms such as akinesia, bradykinesia, tremors, pill-rolling motion, cogwheel rigidity, and postural abnormalities including stooped posture and shuffling gait. The onset is usually 1 to 2 weeks following initiation of therapy or an increase in dosage. Older neuroleptic agents such as haloperidol are more likely to induce these effects, and their use may be contraindicated in patients with Parkinson's disease or parkinsonian symptoms.

Phenylketonuria

Moderate:

Zflex

The acetaminophen in Zflex has a moderate potential interaction with Phenylketonuria.

Several oral acetaminophen and acetaminophen-combination products, particularly flavored chewable tablets, contain the artificial sweetener, aspartame (NutraSweet). Aspartame is converted to phenylalanine in the gastrointestinal tract following ingestion. Chewable and effervescent formulations of acetaminophen products may also contain phenylalanine. The aspartame/phenylalanine content should be considered when these products are used in patients who must restrict their intake of phenylalanine (i.e. phenylketonurics).

Renal Dysfunction

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Renal Dysfunction.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Respiratory Arrest

Major:

loxapine

Loxapine has a major potential interaction with Respiratory Arrest.

The use of neuroleptic agents is contraindicated in comatose patients and patients with severe central nervous system depression. Neuroleptic agents may potentiate the CNS and respiratory depression in these patients.

Seizures

Moderate:

loxapine

Loxapine has a moderate potential interaction with Seizures.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Tachyarrhythmia

Moderate:

loxapine

Loxapine has a moderate potential interaction with Tachyarrhythmia.

Loxapine should be administered cautiously to patients with cardiovascular disease as increased pulse rates and transient hypotension have been reported. In the presence of severe hypotension requiring vasopressor therapy, the preferred drugs may be norepinephrine and angiotensin, as usual doses of epinephrine may be ineffective as loxapine inhibits its vasopressor effect.

Tardive Dyskinesia

Moderate:

loxapine

Loxapine has a moderate potential interaction with Tardive Dyskinesia.

Tardive dyskinesia (TD) has occurred in patients treated with antipsychotic drugs; the syndrome consists of potentially irreversible, involuntary, dyskinetic movements. The risk appears highest in older patients (particularly older women) but it is not possible to predict which patients are likely to develop TD; whether antipsychotic drugs differ in their potential to cause TD is unknown. The risk of TD and the likelihood that it will become irreversible increase with the duration of therapy and the total cumulative dose. The syndrome can develop after relatively brief treatment periods, even at low dosages; it may also occur after discontinuation of therapy. TD may remit (partially or completely) upon discontinuation of antipsychotic therapy, although antipsychotic therapy itself may suppress (or partially suppress) signs/symptoms of TD, possibly masking the underlying process; the effect of symptomatic suppression on the long-term course of TD is unknown. In patients with preexisting drug-induced TD, initiating or increasing the dosage of antipsychotic therapy may temporarily mask the symptoms of TD but could eventually worsen the condition. In patients requiring chronic therapy, the lowest dose and shortest duration of therapy producing a satisfactory clinical response are recommended; the need for continued therapy should be reassessed periodically. If signs/symptoms of TD occur during antipsychotic therapy, discontinuation of the offending agent should be considered; however, some patients may require treatment despite the presence of TD.

Urinary Retention

Moderate:

Zflex

The phenyltoloxamine in Zflex has a moderate potential interaction with Urinary Retention.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Urinary Tract Obstruction

Moderate:

loxapine

Loxapine has a moderate potential interaction with Urinary Tract Obstruction.

Because of the possible anticholinergic action, loxapine should be used cautiously in patients with glaucoma or with a tendency to urinary retention, particularly if used with any other drugs with anticholinergic effect (e.g., antiparkinson medication).

Vomiting

Moderate:

loxapine

Loxapine has a moderate potential interaction with Vomiting.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

More resources

loxapine

A total of 432 drugs are known to interact with loxapine.

Zflex

A total of 760 drugs are known to interact with Zflex.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.