Effect of metronidazole on platelet aggregation.

The effects of metronidazole on platelet aggregation induced by several agonists were studied on guinea pig and human platelet-rich plasma. Metronidazole (0.25-2.5 mg/ml) showed a dose-dependent inhibitory effect on in vitro aggregation of platelets from either source induced by adenosine-5-diphosphate (ADP), platelet aggregating factor (PAF), epinephrine, collagen or convulxin (extracted from Crotalus durissus terrificus venom). Total or partial inhibition was also detected in metronidazole pre-treated guinea pig platelet-rich plasma when challenged with PAF or ADP 45 and 135 min after oral treatment, respectively. This inhibition was both dose and time dependent.