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NuvaRing is the trade name for a combined hormonal contraceptive vaginal ring manufactured by Merck (formerly Schering-Plough, formerly Organon) that is available by prescription. It is a flexible plastic (ethylene-vinyl acetate copolymer) ring that releases a low dose of a progestin and estrogen over three weeks. It is currently used by approximately 1.5 million women worldwide. A recent study found that users of vaginal rings with ethinyl estradiol and etonogestrel have a 6.5 times increased risk of venous thrombosis compared to non-users. This is commensurate with the risk of thrombosis due to the use of combined oral contraceptive pills, which in studies ranged between 2.9 times to 13.7 times the risk. A number of lawsuits have been filed alleging the companies involved concealed the health risks associated with using the NuvaRing, which are currently being settled for $100,000,000. == Mechanism of action == Like all combined hormonal contraceptives, NuvaRing works primarily by preventing ovulation. A secondary mechanism of action is inhibition of sperm penetration by changes in the cervical mucus. Hormonal contraceptives also have effects on the endometrium that theoretically could affect implantation, however no scientific evidence indicates that prevention of implantation actually results from their use. NuvaRing should not be used if a woman is pregnant. NuvaRing delivers 120 µg of etonogestrel (a progestin) and 15 µg of ethinyl estradiol (an estrogen) each day of use. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「NuvaRing」の詳細全文を読む スポンサード リンク
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