Drug Interactions between dasatinib and Niravam

GENERALLY AVOID: Grapefruit and grapefruit juice may significantly increase the plasma concentrations of dasatinib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruit. Because grapefruit juice inhibits primarily intestinal rather than hepatic CYP450 3A4, the magnitude of interaction is greatest for those drugs that undergo significant presystemic metabolism by CYP450 3A4 (i.e., drugs with low oral bioavailability). In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict. Because dasatinib prolongs the QT interval, high plasma levels of dasatinib may increase the risk of ventricular arrhythmias such as torsade de pointes and sudden death.

MANAGEMENT: Patients treated with dasatinib should avoid consumption of grapefruit, grapefruit juice, and any supplement containing grapefruit extract. Some authorities recommend close monitoring for toxicity (e.g., myelosuppression, bleeding complications, fluid retention, bradycardia or other conduction disturbances) and a reduction of dasatinib dosage to a range of 20 to 40 mg daily should be considered if there are no alternatives and concomitant use with a potent CYP450 3A4 inhibitor is necessary.

GENERALLY AVOID: The pharmacologic activity of oral midazolam, triazolam, and alprazolam may be increased if taken after drinking grapefruit juice. The proposed mechanism is CYP450 3A4 enzyme inhibition. In addition, acute alcohol ingestion may potentiate CNS depression and other CNS effects of many benzodiazepines. Tolerance may develop with chronic ethanol use. The mechanism may be decreased clearance of the benzodiazepines because of CYP450 hepatic enzyme inhibition. Also, it has been suggested that the cognitive deficits induced by benzodiazepines may be increased in patients who chronically consume large amounts of alcohol.

MANAGEMENT: The manufacturer recommends that grapefruit juice should not be taken with oral midazolam. Patients taking triazolam or alprazolam should be monitored for excessive sedation. Alternatively, the patient could consume orange juice which does not interact with these drugs. Patients should be advised to avoid alcohol during benzodiazepine therapy.

The use of benzodiazepines with alcohol is not recommended. Patients with acute alcohol intoxication exhibit depressed vital signs. The central nervous system depressant effects of benzodiazepines may be additive with those of alcohol, and severe respiratory depression and death may occur. Therapy with benzodiazepines should be administered cautiously in patients who might be prone to acute alcohol intake.

Benzodiazepines may cause respiratory depression and apnea, usually when given in high dosages and/or by intravenous administration. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with benzodiazepines should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Benzodiazepines, especially injectable formulations, should generally be avoided in patients with sleep apnea, severe respiratory insufficiency, or hypoxia.

Benzodiazepines have the potential to cause dependence and abuse. Tolerance as well as physical and psychological dependence can develop, particularly after prolonged use and/or excessive dosages. However, abrupt cessation following continual use of as few as 6 weeks at therapeutic levels has occasionally precipitated withdrawal symptoms. Addiction- prone individuals, such as those with a history of alcohol or substance abuse, should be under careful surveillance when treated with benzodiazepines. It may be prudent to refrain from dispensing large quantities of medication to these patients. After prolonged use or if dependency is suspected, withdrawal of benzodiazepine therapy should be undertaken gradually using a dosage- tapering schedule. If withdrawal symptoms occur, temporary reinstitution of benzodiazepines may be necessary.

The manufacturers consider the use of benzodiazepines to be contraindicated in patients with acute angle-closure glaucoma or untreated open-angle glaucoma. These agents do not possess anticholinergic activity but have very rarely been associated with increased intraocular pressure.

Benzodiazepines are metabolized by the liver, and the metabolites are excreted in the urine. Chlordiazepoxide, clorazepate, diazepam, flurazepam and quazepam undergo oxidative N-dealkylation to active metabolites that are substantially longer-acting than the parent compound. These metabolites then undergo further biotransformation to pharmacologically inactive products before excretion by the kidney. Therapy with benzodiazepines should be administered cautiously at lower initial dosages in patients with impaired renal and/or hepatic function. Agents that are converted to weakly active, short-acting, or inactive metabolites may be preferable in hepatic impairment. Lorazepam, oxazepam and temazepam are conjugated to inactive metabolites, while alprazolam, estazolam and triazolam undergo hydroxylation to weakly active or inactive metabolites.

Benzodiazepines may cause respiratory depression and apnea, usually when given in high dosages and/or by intravenous administration. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with benzodiazepines should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Benzodiazepines, especially injectable formulations, should generally be avoided in patients with sleep apnea, severe respiratory insufficiency, or hypoxia.

Benzodiazepines are metabolized by the liver, and the metabolites are excreted in the urine. Chlordiazepoxide, clorazepate, diazepam, flurazepam and quazepam undergo oxidative N-dealkylation to active metabolites that are substantially longer-acting than the parent compound. These metabolites then undergo further biotransformation to pharmacologically inactive products before excretion by the kidney. Therapy with benzodiazepines should be administered cautiously at lower initial dosages in patients with impaired renal and/or hepatic function. Agents that are converted to weakly active, short-acting, or inactive metabolites may be preferable in hepatic impairment. Lorazepam, oxazepam and temazepam are conjugated to inactive metabolites, while alprazolam, estazolam and triazolam undergo hydroxylation to weakly active or inactive metabolites.

Benzodiazepines may cause respiratory depression and apnea, usually when given in high dosages and/or by intravenous administration. However, some patients may be susceptible at commonly used dosages, including the elderly, debilitated or severely ill patients, those receiving other CNS depressants, and those with limited ventilatory reserve, chronic pulmonary insufficiency or other respiratory disorders. Therapy with benzodiazepines should be administered cautiously in these patients. Appropriate monitoring and individualization of dosage are particularly important, and equipment for resuscitation should be immediately available if the parenteral route is used. Benzodiazepines, especially injectable formulations, should generally be avoided in patients with sleep apnea, severe respiratory insufficiency, or hypoxia.

The use of benzodiazepines in patients with seizure disorders may increase the incidence or precipitate the onset of generalized tonic-clonic seizures (grand mal). Appropriate anticonvulsant medication might need to be initiated or the dosage increased. Abrupt cessation of benzodiazepine therapy may precipitate seizures and other withdrawal symptoms, particularly after prolonged use and/or excessive dosages. Status epilepticus may occur in patients with a history of seizures withdrawn rapidly from benzodiazepine therapy. Following chronic administration, cessation of benzodiazepine therapy should occur gradually with incrementally reduced dosages. Patients should be advised not to discontinue medication without first consulting with the physician.

Thrombocytopenia, aplastic anemia, agranulocytosis and neutropenia occur with BCR-ABL tyrosine kinase inhibitors. Therapy with these drugs should be administered cautiously in patients with preexisting bone marrow suppression. A complete blood count should be performed every 1-2 weeks for the first month of therapy and then monthly thereafter, or as clinically indicated. To manage myelosuppression, withhold, reduce dose, or discontinue therapy as necessary.

Cardiovascular events, including arterial vascular occlusive events, peripheral arterial occlusive events and ischemic cerebrovascular events have been reported in patients receiving tyrosine kinase inhibitors. If acute signs or symptoms of cardiovascular events occur, patients should seek immediate medical attention. The cardiovascular status and risk factors of patients should be evaluated prior to therapy and cardiovascular monitoring and management should take place during treatment.

Fluid retention occurs with BCR-ABL tyrosine kinase inhibitors therapy and may manifest as pericardial effusion, pleural effusion, pulmonary edema, and/or peripheral edema. Caution should be taken when using these drugs in patients with preexisting fluid retention or congestive heart failure. Monitor and manage patients using standards of care. Interrupt, reduce dose or discontinue therapy as necessary.

Benzodiazepines depress the central nervous system and may cause or exacerbate mental depression and cause suicidal behavior and ideation. Episodes of mania and hypomania have also been reported in depressed patients treated with some of these agents. Therapy with benzodiazepines 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.

Fluid retention occurs with BCR-ABL tyrosine kinase inhibitors therapy and may manifest as pericardial effusion, pleural effusion, pulmonary edema, and/or peripheral edema. Caution should be taken when using these drugs in patients with preexisting fluid retention or congestive heart failure. Monitor and manage patients using standards of care. Interrupt, reduce dose or discontinue therapy as necessary.

Paradoxical reactions, including excitability, irritability, aggressive behavior, agitation, nervousness, hostility, anxiety, sleep disturbances, nightmares and vivid dreams, have been reported with the use of benzodiazepines in psychiatric patients and pediatric patients with hyperactive aggressive disorders. Such patients should be monitored for signs of paradoxical stimulation during therapy with benzodiazepines. The manufacturers do not recommend the use of benzodiazepines for the treatment of psychosis.

Dasatinib has shown to prolong QT interval in a concentration-dependent manner. Caution should be exercised specially in patients with congenital long QT syndrome, patients with hypokalemia, hypomagnesemia, or with history of arrhythmias and on antiarrhythmic medication. Hypokalemia or hypomagnesemia should be corrected before starting treatment. Patients at risk should be monitored with an EKG before treatment and periodically as clinically indicated. Dose adjustments might be needed.

Caution is advised when administering dasatinib to patients with hepatic impairment. Monitoring is recommended and dose adjustment might be necessary.

Dasatinib has shown to prolong QT interval in a concentration-dependent manner. Caution should be exercised specially in patients with congenital long QT syndrome, patients with hypokalemia, hypomagnesemia, or with history of arrhythmias and on antiarrhythmic medication. Hypokalemia or hypomagnesemia should be corrected before starting treatment. Patients at risk should be monitored with an EKG before treatment and periodically as clinically indicated. Dose adjustments might be needed.

Dasatinib has shown to prolong QT interval in a concentration-dependent manner. Caution should be exercised specially in patients with congenital long QT syndrome, patients with hypokalemia, hypomagnesemia, or with history of arrhythmias and on antiarrhythmic medication. Hypokalemia or hypomagnesemia should be corrected before starting treatment. Patients at risk should be monitored with an EKG before treatment and periodically as clinically indicated. Dose adjustments might be needed.

The plasma half-lives of benzodiazepines may be prolonged in obese patients, presumably due to increased distribution into fat. Marked increases in distribution (> 100%) have been reported for diazepam and midazolam, and moderate increases (25% to 100%) for alprazolam, lorazepam, and oxazepam. Therapy with benzodiazepines should be administered cautiously in obese patients, with careful monitoring of CNS status. Longer dosing intervals may be appropriate. When dosing by weight, loading doses should be based on actual body weight, while maintenance dose should be based on ideal body weight to avoid toxicity.

Fluid retention occurs with BCR-ABL tyrosine kinase inhibitors therapy and may manifest as pericardial effusion, pleural effusion, pulmonary edema, and/or peripheral edema. Caution should be taken when using these drugs in patients with preexisting fluid retention or congestive heart failure. Monitor and manage patients using standards of care. Interrupt, reduce dose or discontinue therapy as necessary.

Benzodiazepines depress the central nervous system and may cause or exacerbate mental depression and cause suicidal behavior and ideation. Episodes of mania and hypomania have also been reported in depressed patients treated with some of these agents. Therapy with benzodiazepines 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.

Paradoxical reactions, including excitability, irritability, aggressive behavior, agitation, nervousness, hostility, anxiety, sleep disturbances, nightmares and vivid dreams, have been reported with the use of benzodiazepines in psychiatric patients and pediatric patients with hyperactive aggressive disorders. Such patients should be monitored for signs of paradoxical stimulation during therapy with benzodiazepines. The manufacturers do not recommend the use of benzodiazepines for the treatment of psychosis.

Dasatinib can increase the risk of developing pulmonary arterial hypertension (PAH) which may occur any time after treatment initiation, including after more than 1 year of treatment. Manifestations may include dyspnea, fatigue, hypoxia, and fluid retention. PAH may be reversible with treatment discontinuation. Caution should be exercised in patients with underlying cardiopulmonary disease. If PAH develops, treatment should be discontinued.