A comparison of Norinyl and Brevicon in three sites in Sri Lanka

A set of 3 four-cell randomized, blind clinical trials was carried out in Sri Lanka to evaluate the impact of vitamin supplements and different oral contraceptive formulations. This paper concentrates on the comparisons of oral contraceptives. There seems to be no important difference between Norinyl, a standard-dose oral contraceptive, and Brevicon of a lower estrogen dosage--in either continuation or side effects. Continuation at one site was higher among Norinyl users, but several factors led us to the belief that this difference was due to differences in field worker performance rather than to the pharmacological properties of the drugs. Some differences in side effects were observable along predictable lines; breakthrough bleeding was more common among Brevicon users than Norinyl users, and most other side effects were more frequent among Norinyl users, although these latter differences were quite small, and there were several exceptions.