A randomized double blind study of two oral contraceptives
Sanhueza, H.; Sivin, I.; Kumar, S.; Kessler, M.; Carrasco, A.; Yee, J.
Contraception 20(1): 29-48
1979
ISSN/ISBN: 0010-7824 PMID: 477315 DOI: 10.1016/0010-7824(79)90042-8Document Number: 442424
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.