Mirena, an intrauterine contraceptive device, is now approved to use for eight years

Around 160 million women worldwide use intrauterine devices (IUDs), according to an estimate from 2019. IUD is a T-shaped device inserted into the uterus and used for the slow release of progestin (levonorgestrel), the same hormone found in most oral contraceptive pills. Some advantages of IUDs over pills include: it works quicker, it does not require user intervention such as daily dosing, and they last longer.

Mirena is a 52mg levonorgestrel-releasing intrauterine system introduced to the market 30 years ago in Finland. Mirena is now available in over 120 countries. The clinical trials for Mirena conducted between 1985 and 1994 compared with Copper IUD (which uses copper instead of hormones for contraception) showed that Mirena had a 5-year cumulative pregnancy rate of 0.5%-1.1%. In contrast, the Copper IUD arm had 1.4%-5.9%. Due to its highly effective contraception, the FDA initially approved Mirena’s use for five years. Besides contraception, Mirena is also used to treat heavy menstrual bleeding (HMG). Bayer HealthCare Pharmaceuticals Inc. manufactures Mirena.

A clinical trial – Mirena Extension Trial – was conducted to analyze the extended performance of Mirena for three more years beyond the approved five years (years 6, 7, and 8). Mirena Extension trial (NCT02985541) was a multicenter, open-label, uncontrolled trial for women between 18 to 35 years of age who used Mirena for contraception or HMG for at least 4.5 years. Based on the positive data obtained from years six and seven, the FDA had approved its extension for up to seven years.

The year eight results were released recently and demonstrated the maintenance of high contraceptive efficacy. The cumulative 3-year pearl index was 0.28 (95% Confidence Interval [CI]: 0.03–1.00) and an estimated probability of pregnancy was 0.68% (95% CI: 0.17–2.71). The safety profile was generally acceptable. This allowed the further extension of Mirena’s usage for up to eight years by the FDA.

Mirena is initially released at a rate of 20 mcg/day, then decreases to approximately 10 mcg/day after five years, and again reduces to 8 mcg/day after seven years. After eight years of continued use, the device needs to be replaced with a fresh one (only for contraception).

Besides Mirena, Bayer also manufactures other birth control methods and has products to treat menopausal and gynecological diseases.