Role of the levonorgestrel intrauterine system in effective contraception
Attia, A.M.; Ibrahim, M.M.; Abou-Setta, A.M.
Patient Preference and Adherence 7: 777-785
2013
ISSN/ISBN: 1177-889X PMID: 23990713 DOI: 10.2147/ppa.s36948Document Number: 576220
Norgestrel, a synthetic progestin chemically derived from 19-nortestosterone, is six times more potent than progesterone, with variable binding affinity to various steroid receptors. The levonorgestrel-releasing intrauterine system (LNG IUS) provides a long-acting, highly effective, and reversible form of contraception, with a pearl index of 0.18 per 100 women-years. The locally released hormone leads to endometrial concentrations that are 200-800 times those found after daily oral use and a plasma level that is lower than that with other forms of levonorgestrel-containing contraception. The contraceptive effect of the LNG IUS is achieved mainly through its local suppressive effect on the endometrium, leading to endometrial thinning, glandular atrophy, and stromal decidualization without affecting ovulation. The LNG IUS is generally well tolerated. The main side effects are related to its androgenic activity, which is usually mild and transient, resolving after the first few months. Menstrual abnormalities are also common but well tolerated, and even become desirable (eg, amenorrhea, hypomenorrhea, and oligomenorrhea) with proper counseling of the patient during the choice of the method of contraception. The satisfaction rates after 3 years of insertion are high, reaching between 77% and 94%. The local effect of the LNG IUS on the endometrium and low rates of systemic adverse effects have led to its use in other conditions rather than contraception, as for the treatment of endometrial hyperplasia, benign menorrhagia, endometriosis, adenomyosis, and uterine fibroids.