The effect of the imidazole derivative Dazoxiben (400 mg daily for 1 week) on antipyrine metabolism was examined in six patients with enhanced platelet aggregation. No significant change in antipyrine saliva pharmacokinetics occurred before or after Dazoxiben treatment. The rate of formation of the three main oxidative antipyrine metabolites was similar before and after Dazoxiben. Although Dazoxiben belongs chemically to the imidazole derivatives, which exhibit inhibitory activity on drug metabolism, no influence on antipyrine disposition could be detected.