Phentermine and topiramate and Risperidone interaction

The concomitant use of alcohol or central nervous system (CNS) depressant drugs with phentermine and topiramate extended-release capsules may potentiate CNS depression or other centrally mediated effects of these agents, such as dizziness, cognitive adverse reactions, drowsiness, light-headedness, impaired coordination, and somnolence.

CNS Depressants Including Alcohol Clinical Impact The concomitant use of alcohol or CNS depressant drugs (e.g., barbiturates, benzodiazepines, and sleep medications) with phentermine or topiramate may potentiate CNS depression such as dizziness or cognitive adverse reactions, or other centrally mediated effects of these agents.

CNS Depressants Including Alcohol : May potentiate CNS depressant effects.

Topiramate Oral RISPERDAL administered at doses from 1–6 mg/day concomitantly with topiramate 400 mg/day resulted in a 23% decrease in risperidone C max and a 33% decrease in risperidone AUC 0–12 hour at steady state.

Carbamazepine and other enzyme inducers decrease plasma concentrations of risperidone.

Carbamazepine and Other CYP 3A4 Enzyme Inducers Carbamazepine co-administration with oral RISPERDAL decreased the steady-state plasma concentrations of risperidone and 9-hydroxyrisperidone by about 50%.

Co-administration of other known CYP 3A4 enzyme inducers (e.g., phenytoin, rifampin, and phenobarbital) with risperidone may cause similar decreases in the combined plasma concentrations of risperidone and 9-hydroxyrisperidone, which could lead to decreased efficacy of RISPERDAL CONSTA treatment.

At the initiation of therapy with carbamazepine or other known hepatic enzyme inducers, patients should be closely monitored during the first 4–8 weeks, since the dose of RISPERDAL CONSTA may need to be adjusted.