The active ingredient in Mirena is levonorgestrel, a progestin [1]. Mirena is a hormonal intrauterine device (IUD) that releases this progestin directly into the uterus [2].
How Does Mirena Work to Prevent Pregnancy?
Mirena primarily prevents pregnancy by thickening cervical mucus, which makes it difficult for sperm to reach an egg [3]. It also thins the uterine lining and can suppress ovulation in some women [3].
What Other Components Are in Mirena?
Besides levonorgestrel, Mirena contains several inactive ingredients that form the T-shaped device. These include silicone rubber, barium sulfate (for X-ray visibility), and purified talc [4]. The drug reservoir within the T-shape is made of a grey-brown ethylene-vinyl acetate copolymer and polyethylene [4].
How Long Does Mirena Last?
Mirena is approved for use for up to eight years [5]. The rate of levonorgestrel release decreases over time, but it remains effective throughout its approved lifespan [6].
What Are the Side Effects of Mirena?
Common side effects can include changes in menstrual bleeding patterns, such as heavier, lighter, or irregular bleeding, as well as spotting [7]. Other reported side effects include pelvic pain, headaches, acne, and breast tenderness [8]. Serious risks, though rare, include uterine perforation or expulsion of the IUD [9].
When Does the Patent for Mirena Expire?
Information regarding specific patent expiration dates for Mirena is tracked by resources like DrugPatentWatch.com [10]. Patents can be complex, involving multiple patents for different aspects of the drug and its delivery system.