INJECTABLE CONTRACEPTION

Abstract

This review of progress in the area of injectable contraception focuses on the pharmacokinetics, mode of action, use-effectiveness, bleeding problems, and metabolic effects of medroxyprogesterone acetate, norethisterone enanthate, and monthly injectables. The advantages of injectable contraception include greater efficacy than either oral contraception or IUDs, less heavy bleeding, no need to remember pills, and no effect on lactation. Irregular bleeding constitutes the major drawback of this method. If adequate counseling is provided before the injections are started, discontinuation rates due to irregular bleeding can be reduced. Initial delay in return of fertility is less with norethisterone enanthate than medroxyprogesterone acetate. The issue of the carcinogenicity of both drugs is considered resolved, and there are no clinical effects of altered lipids. This suggests that both these compounds should be freely available as safe, effective contraceptives. Monthly injectable preparations are highly effective as well, and should give better cycle control than longacting regimens. There are inadequate data from which to draw conclusions regarding the return of fertility or metabolic effects and carcinogenesis. These preparations pose logistic and financial problems for national family plannig programs and require users to make more frequent clinic visits. Assessment of the role of monthly injectables should be postponed until further studies have been completed.