A multicentred phase III comparative clinical trial of Mesigyna, Cyclofem and Injectable No.1 given by intramuscular injection to Chinese women: II. The comparison of bleeding patterns

Abstract

Between 1988 and 1992, a randomized phase III clinical trial was conducted in China to compare three monthly injectable contraceptives: Mesigyna, Cyclofem and Injectable No.1. This paper presents a detailed analysis of the menstrual diaries provided by 5098 (89%) of the subjects. In total, 902, 903 and 913 diaries were analyzed to compare bleeding patterns induced by Mesigyna, Cyclofem and Injectable No.1. The first withdrawal bleeding usually occurs 14–20 days after the first injection for all three of these preparations. Thereafter, 50% of Mesigyna users had precisely 3 bleeding/spotting episodes every 90 days, 50% of Cyclofem users had 2–3 and 50% of Injectable No.1 users had 3–4 episodes every 90 days. Relative to users of Mesigyna or Cyclofem, Injectable No. 1 users had 2–3 more bleeding/spotting days, and a shorter length of bleeding/spotting-free intervals in each period. 63.7%, 41.4% and 60.6% of subjects using Mesigyna, Cyclofem and Injectable No.1, respectively, had bleeding patterns similar to their untreated patterns in the first 90-day period. The percentages increased to 82.2% 67.8% and 75.0% in the fourth 90-day period. A total of 1815 diaries for Mesigyna and 1802 for Cyclofem were analyzed for more in depth comparison of these two methods. The number of bleeding/spotting days over four periods showed little difference between the two groups, but there were more spotting days and there was greater individual variability among Cyclofem users. Irregular bleeding in the first three months was 21.1% for Mesigyna and 26.1% for Cyclofem, decreasing to 4.4% and 7.7%, respectively, in the last three months of the treatment year. For Chinese women, Mesigyna provided better cycle control and more acceptable bleeding patterns than either Cyclofem or Injectable No.1.