Drug Interactions between Crantex HC and quetiapine

GENERALLY AVOID: Alcohol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics including hydrocodone. Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills. In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

GENERALLY AVOID: Consumption of alcohol while taking some sustained-release formulations of hydrocodone may cause rapid release of the drug, resulting in high systemic levels of hydrocodone that may be potentially lethal. Alcohol apparently can disrupt the release mechanism of some sustained-release formulations. In study subjects, the rate of absorption of hydrocodone from an extended-release formulation was found to be affected by coadministration with 40% alcohol in the fasted state, as demonstrated by an average 2.4-fold (up to 3.9-fold in one subject) increase in hydrocodone peak plasma concentration and a decrease in the time to peak concentration. Alcohol also increased the extent of absorption by an average of 1.2-fold (up to 1.7-fold in one subject).

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of hydrocodone. The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism of hydrocodone by certain compounds present in grapefruit. Increased hydrocodone concentrations could conceivably increase or prolong adverse drug effects and may cause potentially fatal respiratory depression.

MANAGEMENT: Patients taking sustained-release formulations of hydrocodone should not consume alcohol or use medications that contain alcohol. In general, potent narcotics such as hydrocodone should not be combined with alcohol. Patients should also avoid consumption of grapefruit or grapefruit juice during treatment with hydrocodone.

GENERALLY AVOID: Grapefruit juice and/or grapefruit may increase the plasma concentrations of quetiapine. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit juice but has been reported for other CYP450 3A4 inhibitors. For example, in 12 healthy volunteers, administration of a single 25 mg dose of quetiapine with the potent CYP450 3A4 inhibitor ketoconazole (200 mg once daily for 4 days) increased mean quetiapine peak plasma concentration (Cmax) and systemic exposure (AUC) by 3.4- and 6.2-fold, respectively, and decreased mean oral clearance by 84%. In general, the effects of grapefruit products are concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit (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. High plasma levels of quetiapine may increase the risk and/or severity of serious adverse effects such as extrapyramidal symptoms, tardive dyskinesia, hyperglycemia, dyslipidemia, hyperprolactinemia, orthostatic hypotension, blood pressure increases (in children and adolescents), priapism, QT prolongation, cognitive and motor impairment, dysphagia, heat-related illnesses due to disruption of body temperature regulation, and symptoms of serotonin syndrome (e.g., mental status changes such as irritability, altered consciousness, confusion, hallucination, and coma; autonomic dysfunction such as tachycardia, hyperthermia, diaphoresis, shivering, blood pressure lability, and mydriasis; neuromuscular abnormalities such as hyperreflexia, myoclonus, tremor, rigidity, and ataxia; and gastrointestinal symptoms such as abdominal cramping, nausea, vomiting, and diarrhea).

Food may have varying effects on the absorption of quetiapine from immediate-release versus prolonged-release formulations. In a study examining the effects of food on the bioavailability of quetiapine, a high-fat meal was found to produce statistically significant increases in the quetiapine prolonged release Cmax and AUC of approximately 50% and 20%, respectively. It cannot be excluded that the effect of a high fat meal on the formulation may be larger. In comparison, a light meal had no significant effect on the Cmax or AUC of quetiapine.

Quetiapine may potentiate the cognitive and motor effects of alcohol. The mechanism is likely related to the primary central nervous system effects of quetiapine.

MANAGEMENT: According to the manufacturer, consumption of grapefruit juice should be avoided during treatment with quetiapine. Quetiapine immediate-release tablets may be taken with or without food. It is recommended that quetiapine prolonged release is taken once daily without food or with a light meal. Consumption of alcohol should be limited and used with caution while taking quetiapine.

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.