Clinical comparison between a monophasic preparation and a triphasic preparation

Abstract

The triphasic preparation containing 6 coated tablets of 0.05 mg levonorgestrel (LN) + 0.03 mg ethinyloestradiol (EE), 5 coated tablets of 0.075 mg LN + 0.04 mg EE and 10 coated tablets of 0.125 mg LN + 0.03 mg EE (Triquilar^®/Logynon^®) was compared in a randomized multicentre trial with a monophasic combined pill composed of 0.15 mg desogestrel + 0.03 mg ethinyloestradiol (Marvelon^®).

The main purpose of this study — planned for 6 treatment cycles — was to elucidate possible differences in cycle stability, i.e. the incidence of spotting and breakthrough bleeding episodes and failure of withdrawal bleeding to occur. A total of 555 women were enrolled and completed 3060 cycles. In a randomized fashion 278 of the volunteers were assigned to the triphasic preparation (preparation 1), and 277 to the monophasic combination (preparation 2). 84.5% of the women completed the six months treatment period on both preparations. However, whereas only 6.1% of triphasic takers discontinued medication prematurely because of medical reasons (side-effects), 11.9% of the women on the monophasic preparations did so, mainly because of bleeding irregularities. Calculated in terms of the total number of triphasic cycles the spotting rate was 6.4%, the BTB rate 1.2%. In 0.4% of all cycles spotting + BTB were recorded in the same cycle. The corresponding figures for the monophasic preparation are as follows: spotting 16.5%, BTB 2.8% and spotting + BTB for the same cycles 1.1%. The amenorrhoea rate was 0.2% for the triphasic and 0.9% for the monophasic preparation.

All differences were statistically highly significant (Chi-square test) and not only confined to the beginning of medication, but also present in the 6th treatment cycle. Spotting rates in cycles 1 + 2 for preparation 1 = 10.9%, for preparation 2 = 28.5%; in cycle 6 for preparation 1 = 2.6%, for preparation 2 = 10.3%. BTB rates in cycles 1 + 2 for 1 = 2.0%, for 2 = 6.7%; in cycle 6 for 1 = 0.4%, for 2 = 2.2%.

Another interesting difference between the two preparations concerned body-weight, which remained constant in 75.2% of the triphasic users, but in only 61.1% of the monophasic users. Minor weight gains (+<2kg) occurred in 11.3% of women taking preparation 1 and in 15.4% of women on preparation 2. Only 5.2% of the triphasic users versus 16.7% of the women on the monophasic combination had gained more than 2 kg after 6 months. These differences were also statistically highly significant.