Your search found 1 Results
Injectable Contraceptives Newsletter. 1982 Apr; (9):1-2.Noristerat is the trade name for a long-acting injectable contraceptive. It is a formulation of Norethisterone enanthate (NET-OEN) in 4 parts of Benzobenzoate and 6 parts of castor oil. The active principle of the drug is Norethisterone which is released from intramuscular depot following hydrolysis of the enanthate side-chain by unspecified tissue. NET-OEN is registered at this time in 36 European, African, Asian, Central and South American countries. Extensive ongoing clinical trials have been and are being carried out by several international organizations including the World Health Organization (WHO). Extended preclinical drug safety testing has been carried out in the U.S. The 1st pilot studies with NET-OEN were performed in 1958; regular clinical studies were started in October 1964. Peru was the 1st country to register and market NET-OEN, followed by Chile, Brazil, and Argentina. When toxicity studies revealed breast and liver tumors in rats NET-OEN was discontinued worldwide. Up to 1973 further toxicological studies had been completed in monkeys. These studies could not demonstrate any pathological effects on the experimental animals. Thus, NET-OEN was released again for further studies in February 1973. Investigations revealed that the development of mammarian and hepatic tumors in rats were not restricted to NET-OEN and could be provoked by administration of other substances. It was concluded that the findings in rats cannot be applied to humans. Schering's toxicological studies on NET-OEN include acute toxicity studies, chronic drug safety studies, and combined drug safety and carcinogenicity studies. With regard to the profile of endocrine activity, NET-OEN has been shown to have progestational and no estrogenic activity in humans. Clinical trials with NET-OEN have been performed in more than 20 different countries, and WHO has conducted 2 multi-center studies on long-acting injectable contraceptives comparing NET-OEN with medroxyprogesterone acetate. The data on use-effectiveness obtained from the 1st WHO study showed a higher failure rate for NET-OEN, i.e., 3.6/100 woman years, but a markedly better tolerance for NET-OEN was found. WHO began a 2nd multicenter trial in February 1976 with a modified application scheme. The results obtained thus far showed that by using these modified application schemes the contraceptive reliability of NET-OEN greatly increased.