Cymegesolate (developmental code name Progestin No. 1), also known as cypionyl megestrol acetate or as megestrol acetate 3β-cypionate, is a progestin medication which was never marketed.[1][2][3][4][5][6] It was developed in China in the late 1970s and early to mid 1980s for use as a hormonal contraceptive.[1][2][3][4][5][6] The medication was formulated at a dose of 50–100 mg in combination with a "trace" dose of 0.25–0.5 mg quinestrol as a long-lasting, once-a-month combined oral contraceptive pill.[1][2] This combination has been studied in 1,213 women across a total of 9,651 menstrual cycles, with contraceptive effectiveness of over 99.13% and "very few side effects."[1] At the high dose (100 mg / 0.5 mg), it showed an anovulation rate of only about 60%, and instead mediated its contraceptive effects via a marked anti-implantation effect.[2]
^ abcdeDe-Wei Z (1982). "Research activities in the field of oral contraceptives in the People's Republic of China". Acta Obstetricia et Gynecologica Scandinavica Supplement. 105: 51–60. doi:10.3109/00016348209155319. PMID6952745. S2CID44858028.
^ abChi-ming, L. (1983). New Long Acting Contraceptive Progestagen Studies on Synthesis of “Cymegesolate”[J]. Reproduction & Contraception, 4, 011.
^ abYang YQ, Li SX, Gu XG (August 1985). "[Effect of progestin no. 1 (cymegesolate) on menstrual cycles and plasma levels of progesterone in rhesus monkeys]". Sheng Li Xue Bao (in Chinese). 37 (4): 368–373. PMID3837333.
^ abWu JZ, Yun XJ, Wu MZ, Shen HY, Wang AL (February 1983). "[Clinical study of a long-acting progestogen contraceptive 3-cyclopentyl propionate of megestrol acetate (progestin no. 1)]". Sheng Zhi Yu Bi Yun = Reproduction and Contraception (in Chinese). 3 (2): 36–38. PMID12339176.
^ abXue-jing, W. J. Z. Y., & Mo-zhen, W. (1983). Clinical Study of a Long-Acting Progestogen Contraceptive 3-Cyclopentyl Propionate of Megestrol Acetate (Progestin No. 1)[J]. Reproduction & Contraception, 2, 009.