The anti-trichomonal efficacy and pharmacokinetics of dimetridazole were investigated in the homing pigeon (Columba livia). Dimetridazole was formulated for drinking water medication and as a prolonged-release tablet. To suppress a Trichomonas gallinae infection successfully, medicated drinking water containing dimetridazole (400 mg/L) had to be administered for at least 3 days. A two-day treatment with a dimetridazole tablet (20 mg/tablet) in fasted, as well as in fed, pigeons was shown to be ineffective. After intravenous administration of 20 mg dimetridazole, the drug plasma concentration-time profile fitted a one-compartment open model with a mean half-life of 3.9 h. The absolute bioavailability of the tablet in fasted pigeons was 83.8%. The bioavailability of the tablet administered with food was reduced by 20%. Dimetridazole was rapidly metabolised to (1-methyl-5-nitroimidazol-2-yl) methanol.
