Drug interactions between cilostazol and Plavix

MONITOR: Coadministration of cilostazol with other antiplatelet agents may produce additive pharmacodynamic effects resulting in increased inhibition of platelet function. In 12 healthy male volunteers, coadministration of cilostazol (100 mg twice a day for 10 days) and aspirin (325 mg once a day for the last 5 days of cilostazol administration) resulted in a 23% to 35% increase in inhibition of adenosine diphosphate (ADP)-induced ex vivo platelet aggregation compared to aspirin plus placebo. However, there was no additive or synergistic effect on arachidonic acid-induced platelet aggregation. Cilostazol, with or without aspirin, caused no changes in PT, aPTT, or bleeding time. Drug-related adverse events were generally mild, the most frequent being headache. Another study involving 21 patients with peripheral arterial disease also found no increase in bleeding time when cilostazol (100 mg twice a day) was added to clopidogrel (75 mg once a day), aspirin (325 mg once a day), or clopidogrel and aspirin combined, each for two weeks. The investigators concluded that cilostazol may be used with other platelet inhibitors. However, effects of long-term coadministration in the general population are unknown. During clinical trials, there was no apparent increase in the incidence of hemorrhagic adverse effects in 201 patients who received cilostazol with aspirin (75 to 325 mg daily for up to 137 days) compared to those who received placebo and equivalent doses of aspirin.

MANAGEMENT: Because of theoretical concerns regarding increased inhibition of platelet aggregation, cilostazol should be used cautiously with other antiplatelet agents.