Drug Interaction Report

MONITOR: Coadministration with inhibitors of CYP450 2D6 may increase the plasma concentrations of topical sofpironium, which has been shown to be partially metabolized by the isoenzyme. In a pharmacokinetic study in patients with primary axillary hyperhidrosis, sofpironium systemic exposure (AUC) and peak plasma concentration (Cmax) increased approximately 2-fold following concomitant use with the potent CYP450 2D6 inhibitor paroxetine at a 20 mg oral dose. Clinical data for sofpironium use in combination with other less potent CYP450 2D6 inhibitors are not available.

MANAGEMENT: Caution is advised when sofpironium topical is used concurrently with CYP450 2D6 inhibitors. Patients should be more closely monitored for adverse effects such as blurred vision, urinary retention, difficulty controlling body temperature in warm environments, and dry mouth.

GENERALLY AVOID: Alcohol may have additive CNS- and/or respiratory-depressant effects with propoxyphene. Misuse of propoxyphene, either alone or in combination with other CNS depressants, has been a major cause of drug-related deaths, particularly in patients with a history of emotional disturbances, suicidal ideation, or alcohol and drug abuse.

MANAGEMENT: The use of alcohol during propoxyphene therapy should be avoided. Patients should be warned not to exceed the recommended dosage of propoxyphene and to avoid activities requiring mental alertness until they know how these agents affect them.