A chewable low-dose oral contraceptive: a new birth control option?

Edith Weisberg^1,2
1Sydney Centre for Reproductive Health Research, Research Division of Family Planning NSW, ²Department of Obstetrics and Gynaecology, Queen Elizabeth II Research Institute for Mothers and Infants, University of Sydney, Sydney, Australia

Abstract: A new chewable combined oral contraceptive pill containing ethinyl estradiol (EE) 0.025 mg and norethindrone (NE) 0.8 mg in a 24/4 regimen was approved for marketing in December 2010. Each of the four inactive tablets contains 75 mg ferrous fumarate, which has no therapeutic benefit. The tablet can be taken with food but not water as this affects the absorption of EE. The Pearl index based on intention to treat women aged 18–35 years has been reported at 2.01 (confidence interval [CI] 1.21, 3.14) and for the whole population 1.65 (CI 1.01, 2.55). The effect of a body mass index of >35 was not studied. Regular withdrawal bleeding occurred for 78.6% of women in Cycle 1, but by Cycle 13 almost half the women failed to have a withdrawal bleed. This new formulation provides an intermediate dose of an EE/NE combination that will be useful for women experiencing breakthrough bleeding on the lower-dose EE/NE pill. The convenience of a low-dose pill, which can be chewed without the need for water, will be useful to enable women who have forgotten a pill to take one whenever they remember, provided they carry it with them. The advantage of a 24/4 regimen is better suppression of follicular development in the pill-free interval and may be beneficial for women who experience menstrual cycle-related problems, such as heavy bleeding or dysmenorrhea.

Keywords: combined oral contraceptive, low dose, ethinyl estradiol, norethindrone