Drug Interactions between acetaminophen / dichloralphenazone / isometheptene mucate and pitolisant

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. However, if acetaminophen is used, these patients should be cautioned not to exceed the recommended dosage (maximum 4 g/day in adults and children 12 years of age or older).

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.

MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.

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.

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.

The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.

A variety of abnormal thinking and behavior changes have been reported to occur in association with the use of most anxiolytics, sedatives and hypnotics. Some of these changes include decreased inhibition, aggressiveness, agitation, and hallucinations. These drugs can cause or exacerbate mental depression and cause suicidal behavior and ideation. Therapy with these drugs should be administered cautiously in patients with a history of depression or other psychiatric disorders. Patients should be monitored for any changes in mood or behavior. It may be prudent to refrain from dispensing large quantities of medication to these patients.

The use of combination drugs that have isometheptene mucate may be contraindicated in patients with glaucoma and/or severe cases of renal disease, hypertension, organic heart disease, or hepatic disease.

The use of combination drugs that have isometheptene mucate may be contraindicated in patients with glaucoma and/or severe cases of renal disease, hypertension, organic heart disease, or hepatic 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.

Pitolisant is contraindicated in patients with severe hepatic impairment. Pitolisant is extensively metabolized by the liver. Care should be exercised when using pitolisant in patients with moderate hepatic impairment. It is recommended to monitor patients with mild and moderate hepatic impairment and to adjust the dosage of pitolisant in patients with moderate hepatic impairment as appropriate. No dosage adjustment is recommended in patients with mild hepatic impairment.

The use of combination drugs that have isometheptene mucate may be contraindicated in patients with glaucoma and/or severe cases of renal disease, hypertension, organic heart disease, or hepatic 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.

The use of CNS stimulants can cause psychotic symptoms, suicidal ideation, and aggression, and can exacerbate symptoms of behavior disturbance and thought disorder; CNS stimulants may induce a manic or mixed episode in patients with bipolar disorder. Psychiatric symptoms have been reported in patients with and without history of psychiatric disorders. All patients (particularly those with psychotic or bipolar disorders) should be monitored closely, especially during treatment initiation and at times of dose changes. Extreme caution should be exercised when CNS stimulants are given to patients with a history of psychosis, depression, mania, or bipolar disorder. Prior to initiating therapy, all patients should be screened for risk factors for developing a manic episode (e.g., comorbid or history of depressive symptoms or family history of suicide, bipolar disease, or depression). If any psychiatric symptoms emerge or are exacerbated, treatment suspension should be considered. Some CNS stimulants are contraindicated in patients with marked agitation or anxiety.

The use of combination drugs that have isometheptene mucate may be contraindicated in patients with glaucoma and/or severe cases of renal disease, hypertension, organic heart disease, or hepatic disease.

Pitolisant prolongs the QT interval. The use of pitolisant should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval. The use of pitolisant should also be avoided in patients with a history of cardiac arrhythmias, as well as other circumstances that may increase the risk of the occurrence of torsade de pointes or sudden death, including symptomatic bradycardia, hypokalemia or hypomagnesemia, and the presence of congenital prolongation of the QT interval. The risk of QT prolongation may be greater in patients with hepatic or renal impairment due to higher concentrations of pitolisant. It is recommended to monitor patients with hepatic or renal impairment for increased QTc. Exercise care when using this agent in patients with these conditions.

Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.

Pitolisant prolongs the QT interval. The use of pitolisant should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval. The use of pitolisant should also be avoided in patients with a history of cardiac arrhythmias, as well as other circumstances that may increase the risk of the occurrence of torsade de pointes or sudden death, including symptomatic bradycardia, hypokalemia or hypomagnesemia, and the presence of congenital prolongation of the QT interval. The risk of QT prolongation may be greater in patients with hepatic or renal impairment due to higher concentrations of pitolisant. It is recommended to monitor patients with hepatic or renal impairment for increased QTc. Exercise care when using this agent in patients with these conditions.

In general, anxiolytics, sedatives and hypnotics are extensively metabolized by the liver. Their plasma clearance may be decreased and their half-life prolonged in patients with impaired hepatic function. Therapy with these drugs should be administered cautiously in patients with liver disease (some are not recommended in severe liver impairment), and the dosage should be adjusted accordingly. Laboratory testing is recommended prior and during treatment.

Pitolisant prolongs the QT interval. The use of pitolisant should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval. The use of pitolisant should also be avoided in patients with a history of cardiac arrhythmias, as well as other circumstances that may increase the risk of the occurrence of torsade de pointes or sudden death, including symptomatic bradycardia, hypokalemia or hypomagnesemia, and the presence of congenital prolongation of the QT interval. The risk of QT prolongation may be greater in patients with hepatic or renal impairment due to higher concentrations of pitolisant. It is recommended to monitor patients with hepatic or renal impairment for increased QTc. Exercise care when using this agent in patients with these conditions.

Pitolisant prolongs the QT interval. The use of pitolisant should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval. The use of pitolisant should also be avoided in patients with a history of cardiac arrhythmias, as well as other circumstances that may increase the risk of the occurrence of torsade de pointes or sudden death, including symptomatic bradycardia, hypokalemia or hypomagnesemia, and the presence of congenital prolongation of the QT interval. The risk of QT prolongation may be greater in patients with hepatic or renal impairment due to higher concentrations of pitolisant. It is recommended to monitor patients with hepatic or renal impairment for increased QTc. Exercise care when using this agent in patients with these conditions.

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).

The pharmacokinetics of pitolisant in patients with end-stage renal disease (ESRD) (eGFR of <15 mL/minute/1.73 m2) is unknown. Pitolisant is not recommended in patients with ESRD. It is recommended to adjust the dosage of pitolisant when using this agent in patients with moderate (eGFR 30 to 59 mL/minute/1.73 m2) and severe (eGFR 15 to 29 mL/minute/1.73 m2) renal impairment.

Pitolisant prolongs the QT interval. The use of pitolisant should be avoided in patients with known QT prolongation or in combination with other drugs known to prolong the QT interval. The use of pitolisant should also be avoided in patients with a history of cardiac arrhythmias, as well as other circumstances that may increase the risk of the occurrence of torsade de pointes or sudden death, including symptomatic bradycardia, hypokalemia or hypomagnesemia, and the presence of congenital prolongation of the QT interval. The risk of QT prolongation may be greater in patients with hepatic or renal impairment due to higher concentrations of pitolisant. It is recommended to monitor patients with hepatic or renal impairment for increased QTc. Exercise care when using this agent in patients with these conditions.

Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.