A randomized double blind study of two oral contraceptives

Abstract

To study the question of whether one brand of oral contraceptives may be as acceptable as another for use of publicly-assisted family planning programs, a double blind study of two well-known brands, Ovral and Norinyl, was undertaken in Costa Rica and Trinidad. The pills were randomly assigned to 1,200 women. Common side effects - nausea, dizziness, vomiting, headaches - were associated with both Norinyl and Ovral. Differences in event rates for these conditions were much more marked by country than by the pill used. Ovral was associated with increases in skin problems, notably chloasma, in Cost Rica. A higher percentage of women using Norinyl reported intermenstrual bleeding and spotting in both countries. In Costa Rica continuation rates for Norinyl were adversely affected by this. With these exceptions there appear to be no important differences between the brands that would affect their use in family planning programs.

PIP: A double-blind study of 2 well-known brands of contraceptives, Ovral and Norinyl, was performed in Trinidad and Costa Rica to determine if 1 brand of oral contraceptive were as acceptable as another. Differences in race and ethnic origin were large between the 2 study populations. There were no significant differences in reporting of gastrointestinal side effects for the 2 formulations. Women using Ovral in Costa Rica reported acne and chloasma in significantly greater (P .001) numbers than did women using Norinyl. Participants in Trinidad were virtually free of such complaints. Overall in both study populations, Ovral affected significantly more users (P .05) both with regard to chloasma and all skin conditions than did Norinyl. A moderate excess of cervicitis and cervical erosion among Ovral users in Trinidad was seen; in Costa Rica, cervical erosion occurred in 13% of users of either drug, whereas cervicitis was noted in 3% of each group. Both brands reduced the average number of days of menstrual bleeding in the 2 countries, and both formulations effected a reduction in the % of women reporting relatively heavy menstrual flow. Intermenstrual spotting or bleeding was strongly (P .001 overall) associated with the use of Norinyl; in both countries, the % of women using Norinyl reporting intermenstrual bleeding was at least 2 times that of Ovral users. In Costa Rica, continuation rates for Norinyl were badly affected by the frequency of intermenstrual bleeding (27.9 for Norinyl and 8.2 for Ovral). Otherwise, it is concluded that there were no important differences between the 2 formulations.