Drug Interactions between albendazole and oxcarbazepine

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of albendazole, which is rapidly converted by hepatocytes and intestinal mucosal cells into the active metabolite, albendazole sulfoxide (ABZSX), following absorption. The proposed mechanism is stimulation of gastric acid secretion, as the absorption of albendazole is thought to be pH-dependent. According to the product labeling, plasma concentrations of ABZSX are up to 5-fold higher on average when albendazole is administered with a fatty meal (fat content approximately 40 g) compared to administration in the fasted state. In one study of six healthy male volunteers, administration of a single 10 mg/kg oral dose of albendazole in combination with a high-fat meal (57 g fat, 1399 kcal) increased the mean ABZSX peak plasma concentration (Cmax) and systemic exposure (AUC) by 6.5- and 9.4-fold, respectively, and delayed the time to reach Cmax (Tmax) from 2.5 to 5.3 hours compared to administration in the fasted state with water. The elimination half-life was not affected.

MONITOR: Grapefruit juice may increase the oral bioavailability of albendazole, which is rapidly converted by hepatocytes and intestinal mucosal cells into the active metabolite, albendazole sulfoxide (ABZSX), following absorption. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In six healthy male volunteers, administration of a single 10 mg/kg oral dose of albendazole in combination with 250 mL of double-strength grapefruit juice increased the mean ABZSX peak plasma concentration (Cmax) and systemic exposure (AUC) by 3.2- and 3.1-fold, respectively, compared to administration with water. However, because pharmacokinetic interactions involving grapefruit juice are often subject to a high degree of interpatient variability, the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: To ensure maximal oral absorption, albendazole should be taken with food. Grapefruit juice may also enhance the oral bioavailability of albendazole.

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.