Abstract
In the nine years since synthetic LH-RH became available, extensive basic and clinical investigations have been carried out. Synthesis of more than 1000 of LH-RH analogs has also been accomplished. Long-acting superactive analogs of LH-RH administered intermittantly (on alternate days) in small doses may find therapeutic application for the treatment of infertility, but regimens which would ensure a high degree of clinical success have not yet been devised. Large doses of these analogs cause paradoxical antifertility effects in animals and human beings. These effects are being considered for the development of contraceptive methods. Powerful competitive inhibitory analogs of LH-RH have also been synthesized, which block ovulation in laboratory animals. Several inhibitory analogs of LH-RH have been tested in men and women and shown to be active. The synthetic approach based on inhibitory analogs of LH-RH has been clearly proven to be feasible for development of new methods for birth control.