Potential drug interactions with the novel antimigraine compound zolmitriptan (Zomig, 311C90)

Seven randomized studies in healthy volunteers have investigated interactions between zolmitriptan (Zomig, formerly 311C90), a 5HT1B/1D agonist for acute migraine therapy, and selected drugs with which there was a possibility of interaction or a likelihood of concurrent use. Co-administration of oral dihydroergotamine, ergotamine, pizotifen, fluoxetine, paracetamol (acetaminophen)/metoclopramide or selegiline had no clinically significant effects on the pharmacokinetics of zolmitriptan or its metabolites, although small changes were observed in some cases. Co-administration of propranolol resulted in a 56% increase in the area under the plasma concentration-time curve (AUC) of zolmitriptan and a 11% decrease in the AUC of the active metabolite 183C91. However, these pharmacokinetic changes are unlikely to be relevant at lower clinical doses. Moclobemide, a monoamine oxidase A (MAO-A) inhibitor, decreased the clearance of zolmitriptan and, in particular, 183C91. This suggests that MAO-A is involved in the metabolism of 183C91 and it may be prudent to limit the daily zolmitriptan dose in migraine patients maintained on a MAO-A inhibitor. The clinically insignificant blood pressure increases produced by zolmitriptan, and the tolerability profile of this agent, were unaffected by any of the concomitant medications. Clinically significant interactions between zolmitriptan and commonly co-prescribed antimigraine therapies are unlikely.