Once-a-month injectable contraceptives: Efficacy and reasons for discontinuation
Koetsawang, S.
Contraception 49(4): 387-398
1994
ISSN/ISBN: 0010-7824 PMID: 8013221 DOI: 10.1016/0010-7824(94)90034-5Document Number: 285898
This literature review examines the efficacy and reasons for discontinuation of 4 combined progestogen-estrogen, once-a-month injectable contraceptives: Deladroxate, Cyclofem, Mesigyna, and Chinese injectable No. 1. Deladroxate is used mainly in Latin America, while the Chinese injectable No. 1 is largely limited to China. Among 18 studies, no pregnancies occurred in the 3017 women using Deladroxate (32,857 woman-months). It was well accepted, but the manufacturer withdrew it from the market after studies showed that the progestogen (dihydroxyprogesterone acetophenide) caused dogs to develop breast cancer and rats to develop an odd pituitary hyperplasia. Of the 4 once-a-month injectables, Cyclofem and Mesigyna provide the most promise. They are very effective at preventing pregnancy (0-0.23/100 women-years of use and 0.08-0.48/100 women-years of use, respectively). Acceptance of Cyclofem and Mesigyna was high. Side effects were limited and had minimal importance. An advantage of Cyclofem and Mesigyna is their much better cycle control than the once-every-3 months injectable Depo-Provera. The failure rate of the Chinese Injectable No. 1 on the once-a-month injection schedule was too high (10.35/100 women-years of use). When researchers doubled the dose in the 1st month of use, however, efficacy was satisfactory (0.8/100 women-years of use). The main drug-related complaint and reason for discontinuation of all once-a-month injectables was abnormal bleeding. Another key reason for discontinuation was missed appointment, suggesting that a frequent injection schedule poses a problem. Good planning and health workers properly selecting users and providing them good counseling may overcome this problem. Frequent visits would increase the staff work load.