Two 0.75-mg doses of levonorgestrel administered 12 hours apart and a single 10-mg dose of mifepristone are both effective emergency contraception (EC) options, prior research has shown. Researchers for this World Health Organization (WHO) study compared the efficacy and side-effects profile of these regimens, as well as a third, previously untested alternative: a single 1.5-mg dose of levonorgestrel.
Methods and results
The evidence presented here, from randomized blinded trials, shows that a single l.5-mg dose of levonorgestrel is as effective as 2 doses of 0.75 mg taken 12 hours apart. The findings of this study, and others like it, also indicate that efficacy continues for up to 5 days—not the 72 hours to which we have limited EC use in the past.2,3 The WHO group also found that the progesterone antagonist mifepristone (“RU 486”) is not a better EC than levonorgestrel.
Who may be affected by these findings?
Sexually active women.
This study simplifies the postcoital contraceptive regimens established by Yuzpe decades ago and still in use today.1 We can now tell patients seeking EC, “Take these 2 tablets (of 0.75-mg levonorgestrel) together as soon as possible up to 5 days after unprotected intercourse.” This off-label instruction is firmly supported by evidence from the current study, as well as other trials.2,3 (Although the extended therapeutic opportunity demonstrated in this study applies specifically to EC with levonorgestrel, it presumably also holds true for older, less-effective forms of EC, like birth-control pills containing levonorgestrel and estrogen.)
Unfortunately, FDA approval may come slowly. If this simpler levonorgestrel regimen is accompanied by advance prescription and direct pharmacy access (as in the states of Alaska, Washington, and California), it could lead to a reduction in abortion rates beyond that already achieved with the expanded use of EC and other contraceptives.
Although mifepristone remains an effective EC option, it is more expensive than levonorgestrel and unlikely to be considered for over-the-counter use because of its additional abortifacient actions. Levonorgestrel, on the other hand, is inexpensive and has a long history of safety.
Levonorgestrel is an effective, economical alternative to mifepristone for EC, and a single 1.5-mg dose is a viable option.