Quinuronium levels in ovine plasma as determined by an in vitro/in vivo system with Babesia rodhaini.

Quinuronium was shown to have a babesicidal activity in vitro. In vitro/in vivo system with Babesia rodhaini gave an in vitro EC50 for 13.5 ng/ml. Quinuronium levels in ovine plasma increased to a maximum mean of approximately 27 ng/ml at 2 hours with a gradual decay from 8 hours up to almost no detectable levels at 48 hours following administration of therapeutic dose (1 mg/kg s.c.). This study supports previous reports of the use of Babesia rodhaini as an organism in screening antibabesials. The in vitro/in vivo model can be used to monitor quinuronium levels in ovine plasma. Second treatment with quinuronium may be administered after 24 to 48 hours whenever clinically indicated.