Lybrel: New formulation of levonorgestrel 90 mcg/ethinyl estradiol 20 mcg recently approved by FDA for the prevention of pregnancy

Key Points

New formulation/dosing regimen

Lybrel
Levonorgestrel 90 mcg/ethinyl estradiol 20 mcg
WYETHContinuous-use combination oral contraceptive approved for the prevention of pregnancy
This contraceptive is the first low-dose combination pill that is taken 365 days per year, thus leading to a cessation of bleeding. Like other combination oral contraceptives, this agent suppresses gonadotropins, inhibiting ovulation and changing the cervical mucus and endometrium to reduce the likelihood of fertilization and implantation. This agent was approved on May 22, 2007, for the prevention of pregnancy in women who elect to use oral contraceptives as a method of contraception.

Efficacy. The efficacy of this agent was studied in two 1-year clinical trials in patients aged 18 to 49 years. The first study was a 1-year, open-label clinical trial that enrolled 2,134 patients in North America. A total of 1,213 patients (56.8%) discontinued treatment prematurely. The efficacy of this agent was assessed by tabulating the number of pregnancies that occurred during treatment and within 14 days of the last dose. Among patients aged ≤35 years, 23 pregnancies occurred during 12,572 pill packs of use (Pearl Index, 2.38; 95% CI, 1.51–3.57; 1-y life table pregnancy rate, 2.39; 95% CI, 1.57–3.62). Among patients aged ≤35 years who took the pills exactly as directed, 15 pregnancies occurred (Pearl Index, 1.55; 95% CI, 0.87–2.56; 1-y life table pregnancy rate, 1.59; 95% CI, 0.95–2.67). In the second study, which was conducted in Europe, 641 patients were randomized to either continuous-use levonorgestrel 90 mcg/ethinyl estradiol 20 mcg (n=323) or the cyclic comparator (levonorgestrel 100 mcg/ethinyl estradiol 20 mcg) (n=318). Among patients aged ≤35 years, 1 pregnancy occurred within 14 days after the last dose in those patients treated with continuous-use levonorgestrel/ethinyl estradiol (2,756 pill packs) versus 3 pregnancies in the cyclic comparator group (2,886 pill packs).

Dosing. This contraceptive is taken every day. Patients should take the pill at the same time each day. If patients are not currently taking any other contraceptive therapy, they should begin taking this agent on Day 1 of the menstrual cycle (during the first 24 h of the menstrual period). If patients are currently taking a 21-day or 28-day combination oral contraceptive, they should begin taking this agent on Day 1 of the withdrawal bleed (≤7 d after the last active tablet). If patients are currently taking a progestin-only pill, they should begin taking this agent the day after taking a progestin-only pill. If patients are currently using an implant for contraception, they should begin taking this agent on the day of implant removal. If patients are currently using an injection for contraception, they should begin taking this agent on the day their next injection is due.