Comparison of contraceptive acceptability of levonorgestrel and ethinyl oestradiol administered in one three-phasic (Trionetta) and one monophasic (Neovletta) version.

In a Swedish multicenter study, a total number of 835 women completed a total of 6472 treatment cycles. Half of them were allotted at random to use the monophasic oral contraceptive Neovletta, also known as Microgynon 30 (30 micrograms ethinyl oestradiol + 150 micrograms levonorgestrel in each tablet). The second half was allotted to Trionetta, also known as Triquilar, Trigynon and Logynon (6 tablets with 30 micrograms ethinyl oestradiol + 50 micrograms levonorgestrel, 5 tablets with 40 micrograms ethinyl oestradiol + 75 micrograms levonorgestrel and 10 tablets with 30 micrograms ethinyl oestradiol + 125 micrograms levonorgestrel). The latter version was also present in a 28-day version containing in addition 7 "placebo" tablets to be used in the otherwise tablet-free interval. The contraceptive reliability was excellent although one pregnancy occurred in the three-phase version. It could be attributed to patient failure. In all aspects of bleeding control, the three-phasic pill proved to be superior to the reference monophasic preparation. The extreme low incidence of missed withdrawal bleeding and stability already during the first months of use are noteworthy features. For both preparations, continuation rate was at six months of use about 85% and at 12 months it was a similar figure. The most common reason for withdrawal was bleeding, about 5% each for both preparation. No serious side-effects were reported. The study clearly indicates that the three-phasic version is a major improvement in spite of a considerably decreased total dose of the gestagen.