Circadian plasma level profile of lisuride in rats and mice after continuous administration via the diet

Lisuride (Dopergin, CAS 18016-80-3), a dopamine D2 agonist, was administered 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 24 h) were determined by measuring lisuride concentrations by radioimmunoassay. At all doses a plateau-like plasma level of lisuride was observed. A clear circadian rhythm of lisuride concentrations (highs during night, low levels during day) 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 same 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.