Statement on injectable contraception
Ippf Medical Bulletin 16(6): 3-4
1982
ISSN/ISBN: 0019-0357 PMID: 12338511 Document Number: 393120
Injectable hormonal contraception with 2 longacting steroidal preparations--norethisterone enanthate (NET-EN) and depot medroxyprogesterone acetate (DMPA)--provides an effective means of fertility regulation and has become an important method of family planning. DMPA and NET-EN have several advantages which make them particularly appropriate for some women and acceptable in family planning programs. A single injection can provide highly effective contraception for 2 or more months, delivery is simple, independent of coitus, and ensures periodic contact with medical or other trained health personnel. Currently, DMPA is registered as a therapeutic agent in nearly all countries and as a contraceptive agent in over 80 developed and developing countries. NET-EN is registered as a contraceptive in 40 countries. Administered by intramuscular injection in an aqueous microcrystalline suspension, DMPA exerts its contraceptive effect primarily by suppression of ovulation, but its effects on the endometrium, the uterine tubes, and the production of cervical mucus may also play a role in reducing fertility. DMPA as a contraceptive agent is generally given at a dosage of 150 mg every 90 days. NET-EN when administered as an intramuscular injection of an oil preparation at a dose of 200 mg inhibits ovulation. It should be administered at 8 weekly intervals for the 1st 6 months of use, then at intervals of 8 or 12 weeks. Longterm animal studies with DMPA have been completed mainly on beagle bitches and rhesus monkeys, and similar studies with NET-EN are nearing completion. None of the findings in beagles is considered applicable to human populations because the beagle responds differently than humans to steroidal hormones. None of the deaths among rhesus monkeys was attributable to effects of the drug. Endometrial carcinoma was found in 2 of the replacement monkeys but the number of animals was too small for statistically significant studies, and it is not possible to conclude whether DMPA or NET-EN caused these cancers or instead failed to prevent them. Despite more than 18 years of use and an estimated 13 million women who have ever used DMPA or NET-EN, no case has been recorded of an endometrial malignancy in women so exposed. There is no evidence at this stage of a causal association, either anecdotal or scientific. No evidence of an increased risk of malignant and premalignant disease of the uterine cervix has been found in DMPA users. There is sufficient evidence from investigations in several countries that DMPA and NET-EN may increase both milk production and the duration of lactation. The only clinical metabolic effect attributed to DMPA is weight gain. NET-EN and DMPA are associated with disruption of the menstrual cycle and irregular bleeding.