CIRCADIAN PLASMA-LEVEL PROFILE OF LISURIDE IN RATS AND MICE AFTER CONTINUOUS ADMINISTRATION VIA THE DIET

Lisuride (Dopergin(R), CAS 18016-80-3), a dopamine D-2 agonist, was ad ministered to male and female rats and mice continuously via the diet for 14 days. The doses were 0.2 mg/kg/d in mice and 1 mg/kg/d in mice and rats. Plasma level profiles (0-22 or 2 h) were determined by measu ring lisuride concentrations by radio-immunoassay. At all doses a plat eau-like plasma level of lisuride was observed. A clear circadian rhyt hm of lisuride concentrations (highs during night, low levels during d ay) was found for male rats (1 mg/kg/d) and for male mice (0.2 mg/kg/d ). Female animals did not show this phenomenon as pronounced. At the s ame dose of 1 mg/kg/d rats showed higher plasma levels than mice. For males the ratio of total AUCs was 1.9 and for female animals 8.6.