Clinical comparative study of oral contraceptives containing 30 microg ethinylestradiol/150 microg levonorgestrel, and 35 microg ethinylestradiol/250 microg norgestimate in Thai women.

The study was conducted to compare cycle control, efficacy and side effects of two oral contraceptives containing 30 microg ethinylestradiol (EE)/150 microg levonorgestrel (LNG) and 35 microg ethinylestradiol (EE)/250 microg norgestimate (NGM). An open-label, randomized, comparative study was conducted in which 140 healthy women received the 30 microg EE/150 microg LNG or 35 microg EE/250 microg NGM preparation for six treatment cycles. There were no significant statistical differences between both groups in terms of cycle length and amount of withdrawal bleeding. The mean duration in the 35 microg EE/250 microg NGM group was longer than 30 microg EE/150 microg LNG group with significant statistical difference. More patients in 35 microg EE/250 microg NGM group experienced BTT at each cycle compared with the 30 microg EE/150 microg LNG group, but was not statistically significant. There was no amenorrhea nor pregnancies occurring in either group. No significant changes in body weight or blood pressure were found in both groups. The incidence of adverse events in both groups was low and tended to decrease with time. Statistically significant differences were observed for headache and dizziness, which occurred more in the 30 microg EE/150 microg LNG group. In conclusion, 35 microg EE/250 microg NGM provides reliable contraceptive efficacy. It also provides good cycle control equal to 30 microg EE/150 microg LNG with a lower incidence of minor adverse effects such as headache and dizziness compared to 30 microg EE/150 microg LNG.