Existing once-a-month combined injectable contraceptives.

Long-acting contraception by monthly intramuscular injection is an attractive method for family planning which fills a gap in birth control technology. The main advantage of this approach over long-acting (2-6 months) progestin injectables is much better cycle control. To achieve this goal, an estrogen had to be included in the formulation with significant reduction in the progestin dose. Until 1976, there were only three monthly injectables available (Injectable No. 1, Cycloprovera and Deladroxate), but they were faced with logistic, toxicological or clinical problems. It took over 15 years to resolve many of these problems and add a new product (Mesigyna = 50 mg norethisterone enantate plus 5 mg estradiol valerate in an oily solution). Cycloprovera, at a lower dose, received the new name of Cyclofem and Deladroxate was manufactured under the trade names of Perlutal or Topasel. The latter requires in-depth re-evaluation of its toxicological hazards. There are many other formulations currently being developed with incomplete data so far on safety and efficacy.