Effective antagonists of the luteinizing hormone releasing hormone which release negligible histamine

The objective of the research was the achievement of antagonists of the luteinizing hormone releasing hormone (LHRH) which would have adequate antagonistic activity to prevent ovulation, and yet would not have a pronounced structural feature to release a histamine, in vivo. Some existing antagonists of LHRH produced edema of the face and extremities in rats. This recent recognition of the edematogenic and anaphylactoid activities of an antagonist of LHRH necessitated new structural changes if such antagonists were to be considered for potential use as contraceptive agents in the human. Consequently, 57 peptides have been designed, synthesized and bioassayed toward achieving a potent antagonist which releases negligible histamine. Since there was no predictable structural sequence which offered assurance of such achievement, it was necessary to design, synthesize and bioassay a very large number of peptides having diverse structural changes toward ultimately discovering an antagonist with the necessary potency of antiovulatory activity and the necessary negligible release of histamine. Ultimately, this objective was achieved, and this application describes the diverse and unpredictable many positive steps which finally led to the objectives.