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Once-a-month injectable contraceptives: efficacy and reasons for discontinuation

1994; Elsevier BV; Volume: 49; Issue: 4 Linguagem: Inglês

10.1016/0010-7824(94)90034-5

1879-0518

Suporn Koetsawang,

Pregnancy and Medication Impact

Reports of the phase III clinical trials on four combined progestogen-estrogen once-a-month injectable contraceptives, Deladroxate, Cyclofem, Mesigyna and Chinese Injectable No. 1, are reviewed focussing on efficacy and reasons for discontinuation. Deladroxate, currently used in many Latin American countries has proved to be highly effective and well accepted. However, this combination was withdrawn by the original manufacturer because the progestogen component of this drug induced a high number of breast cancers in dogs and very curious pituitary hyperplasia in rats. Cyclofem and Mesigyna were found to be highly effective and highly acceptable drugs. Side-effects were minimal and were of minor importance. The Chinese Injectable No. 1 had unacceptably high failure rates with a monthly injection schedule. After doubling the dose in the first month of use, the efficacy was satisfactory. It was found that all monthly injectable contraceptives provided better cycle control than the every 3 months depot-medroxyprogesterone acetate, although abnormal bleeding was still the main drug-related complaint and reason for discontinuation. Missed appointment is another reason for discontinuation which might reflect the problem of frequent injection schedule, thus indicating the need for proper selection of the users and good counselling.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.