Injectable steroids as a method of contraception.
This review discusses clinical aspects and mechanism of action of various injectable steroids used for contraception. The clinical effectiveness of various injectables is presented tabularly, with the following compounds having notable failure rates: medroxyprogesterone, 400 mg, 9.5 pregnancy/100 woman years; SH 582, 200 mg, 37/100 woman years; SH 582, 2.5 mg, 30/100 woman years; oxagesterone, 50 mg, 22/100 woman years. Contraceptive efficacy of medroxyprogesterone acetate, norethindrone enanthate, and Deladroxate was confirmed. Cycle control using injectables was generally good, but oral estrogens can be used with the injectables to help cycle control if needed. Clinical side effects to pure progestogens are minimal, although headaches, dizziness, dyspepsia, or nonspecific effects have been noted. Addition of estrogen leads to breast symptoms in 9-13% of cases, and sometimes to weight gain, nausea, and vomiting. Use of injectables is particularly encouraged for postpartum women. Despite cycle irregularities associated with progestogen injectables, acceptability is good--drop-out rate is in the 25% range for the commonly used compounds. Fertility is reestablished within 5 weeks to 4 months after injections cease. Possible mechanisms of action of injectables include: inhibition of ovulation either due to inhibition of luteinizing hormone or direct effect on the ovary; effect on the endometrium; or effect on cervical mucus such that it becomes hostile to spermatozoa.