A clinical overview of a new triphasic contraceptive containing gestodene

Abstract

In three ongoing open studies conducted by 50 investigators in Europe, South America, and New Zealand, 639 subjects followed a new triphasic regimen of gestodene (GTD) and ethinyl estradiol (EE) for 3,020 cycles. One study used GTD + EE only, but in each of the other two studies a comparator oral contraceptive (OC) also was given: norethisterone (NET) + EE in one and desogestrel (DSG) + EE in the other. The objective of all three studies was to assess the efficacy, cycle control, and safety of the triphasic GTD + EE. The following is a report of the interim results. Statistical analysis was performed only on differences between groups in the incidences of bleeding irregularities. During six treatment cycles, subjects either followed the GTD + EE regimen (50 micrograms GTD + 30 micrograms EE for 6 days, 70 micrograms GTD + 40 micrograms EE for 5 days, and 100 micrograms GTD + 30 micrograms EE for 10 days) or took triphasic NET + EE or monophasic DSG + EE. Each cycle concluded with a seven-day hiatus in study medication. No pregnancies occurred with any of the contraceptive preparations (Pearl Index = 0). Compliance was good in all studies and a majority of subjects were still participants at cycle 6. Normal bleeding was reported during 92% of the total evaluable cycles of GTD + EE use. Cycle control with GTD + EE was superior to that with NET + EE or DSG + EE: Breakthrough bleeding occurred in 1.5% of the pooled GTD + EE cycles versus 6.6% of the NET + EE cycles and 2.6% of the DSG + EE cycles; spotting occurred in 4.5% of the GTD + EE cycles versus 9.7% of the NET + EE cycles and 10.3% of the DSG + EE cycles; and breakthrough bleeding plus spotting occurred in 2.1% of the GTD + EE cycles versus 8.1% of the NET + EE cycles and 4.6% of the DSG + EE cycles. Amenorrhea occurred in 2.0% of the cycles with NET + EE, but was reported by only 0.3% of all the subjects given GTD + EE and 0.7% of those given DSG + EE. Cycle length and intensity of bleeding changed little during the use of any of the study preparations. Mean length of withdrawal bleeding during the GTD + EE regimen shortened from 4.5 days (prestudy) to 4.0 days. With each OC, the subjects' mean weight during cycles 3 and 6 differed less than 0.5 kg from baseline values.(ABSTRACT TRUNCATED AT 400 WORDS)