The hormones prevent pregnancy for one month mainly by:
- Preventing ovulation
- Thickening cervical mucus (which makes it harder for sperm to swim through)
- Thinning the lining of the uterus, making it less receptive to the implantation.
Lunelle is a monthly injection made up of estradiol cypionate and medroxyprogesterone. It became available in the United States in 2000, but its prefilled syringes were voluntarily recalled in 2002 due to a lack of assurance of full potency and possible risk of contraceptive failure. In October 2003, Pfizer discontinued manufacturing Lunelle, so it is no longer available in the US.
Cyclofem and Mesigyna in Other CountriesA similar shot is now sold under the name Cyclofem and is available in 18 countries (mostly in Latin America and Asia).
Mesigyna is another type of combined injection made up of estradiol valerate and norethisterone enantate. It is equally effective as Cyclofem and is also not available in the U.S. Today, it is found in 36 countries, primarily in Latin America and Asia.
Lunelle also marketed under: Cyclofem, Cyclofemina, Feminena, Novafem, Lunella, and Cyclo-Provera
Mesigyna also marketed under: Norigynon, Mesigyna Instayect, Mesygest, and No 3 injectable Norigynon