Attia Abdelhamid M, Ibrahim Magdy M, Abou-Setta Ahmed M
Department of Obstetrics and Gynecology, Cairo University, Cairo, Egypt.
Patient Prefer Adherence. 2013 Aug 9;7:777-85. doi: 10.2147/PPA.S36948. eCollection 2013.
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.
炔诺孕酮是一种化学合成的孕激素，由19-去甲睾酮衍生而来，其效力是孕酮的6倍，对各种甾体受体具有可变的结合亲和力。左炔诺孕酮宫内节育系统（LNG IUS）提供了一种长效、高效且可逆的避孕方式，每100名妇女年的妊娠率为0.18。局部释放的激素导致子宫内膜浓度是每日口服后浓度的200 - 800倍，血浆水平低于其他含左炔诺孕酮的避孕方式。LNG IUS的避孕效果主要通过其对子宫内膜的局部抑制作用实现，导致子宫内膜变薄、腺体萎缩和间质蜕膜化，而不影响排卵。LNG IUS通常耐受性良好。主要副作用与其雄激素活性有关，通常较轻且短暂，在最初几个月后会消失。月经异常也很常见，但耐受性良好，甚至在选择避孕方法时对患者进行适当咨询后会变得令人满意（如闭经、月经过少和稀发月经）。放置3年后的满意度很高，达到77%至94%。LNG IUS对子宫内膜的局部作用和较低的全身不良反应发生率使其被用于避孕以外的其他情况，如治疗子宫内膜增生、良性月经过多、子宫内膜异位症、子宫腺肌病和子宫肌瘤。
