ABSTRACT
PIP: After 20 years of clinical experience, injectable hormonal contraceptives such as norethisterone enanthate (NET) and medroxyprogesterone acetate (MPA) remain one of the most controversial methods currently used for temporary control of fertility in women. Since December 1980 this controversy has been accentuated in Mexico with issuing of regulations by the Secretary of Health and Welfare which initially did not permit promotion of long-acting injectable hormones for contraception purposes, and later, in June 1981, a reconsideration which exclusively authorized use of NET as an injectable contraceptive. Undeniably these official measures and the scientific information, occasionally contradictory, have created confusion about the indications and risks of using these formulations in clinical work. This paper presents an anlysis of the basic pharmacological aspects of long-acting contraceptive progestagens, potential risks for side effects, and some clinical rules for safe use. The authors conclude that injectable contraceptives will continue holding a definite place among hormonal methods of temporary fertility control, particularly with the advent of new administration schemes for NET which have elevated its contraceptive efficacy without appreciably increasing complications. The more rapid metabolism of NET, manifested in the absence of significant effects on body weight, less alteration of the menstrual cycle, and more rapid return of fertility after discontinuation, has considerably increased its popularity, and the possibility exists that with time and an increase in clinical experience, it may replace MPA as the injectable contraceptive of choice. Nevertheless, while investigative studies have not clearly defined the possibilities of potential risk of using these contraceptives, its clinical use must be governed by appropriate selection and careful follow-up of patients.^ieng