Drug Interaction Report

MONITOR: Maraviroc may potentiate the hypotensive effect of some medications. In clinical trials, symptomatic postural hypotension was observed more often with maraviroc than with placebo when administered to healthy volunteers at higher than recommended dosages. However, when given at the recommended dosage to HIV subjects, postural hypotension occurred at a rate similar to placebo (approximately 0.5%).

MANAGEMENT: Caution is advised when maraviroc is prescribed to patients on concomitant medications known to lower blood pressure. Close monitoring for development of hypotension is recommended. Ambulatory patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their doctor if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia.

GENERALLY AVOID: Concurrent use of ethanol and phenothiazines may result in additive CNS depression and psychomotor impairment. Also, ethanol may precipitate dystonic reactions in patients who are taking phenothiazines. The two drugs probably act on different sites in the brain, although the exact mechanism of the interaction is not known.

MANAGEMENT: Patients should be advised to avoid alcohol during phenothiazine therapy.

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.

Administration with food may reduce the bioavailability of maraviroc. According to the product labeling, coadministration of a 300 mg dose of maraviroc with a high-fat breakfast reduced maraviroc peak plasma concentration (Cmax) and systemic exposure (AUC) by 33% in healthy volunteers. However, no food restrictions were used in the clinical studies that demonstrated the safety and efficacy of maraviroc. Therefore, maraviroc can be taken with or without food at the recommended dosage.