Simple potency test for LH-RH preparations.

Proestrous rats, pretreated with fluphenazine dihydrochloride (FD) to block ovulation, were used to compare the ovulation-inducing activity of two synthetic LH-RH preparations; one was received from the National Institute for Biological Standards and Control labelled Gonadorelin acetate (77/596) and the other one was prepared in Ayerst Research Laboratories, Montreal, Canada, and labelled Gonadorelin hydrochloride (AY-24,031-A-23). It was found that FD blocked ovulation and graded doses of both LH-RH preparations induced dose-dependent ovulation in FD-treated rats. There were no significant differences between the biological potencies of both preparations. Both preparations, when administered intramuscularly at 1 μg/kg body weight, induced ovulation in 80% of the FD-pretreated proestrous rats. This simple test could be used to evaluate the biological potency of LH-RH and its analogues in less than 24 h.