Drug Interaction Report

Coadministration with rizatriptan may alter the plasma concentrations of drugs that are primarily metabolized by CYP450 2D6. Rizatriptan has been shown to be a competitive inhibitor of CYP450 2D6 in vitro, but only at high, clinically irrelevant concentrations and a clinically significant inhibitory effect on CYP450 2D6 has not been demonstrated in clinical drug interaction studies. Based on these observations, rizatriptan may be administered with CYP450 2D6 substrates without the need for increased clinical monitoring

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.