Tri-Norinyl is a birth control pill that is both a "combined" and a "triphasic" oral contraceptive. The drug is a combined oral contraceptive because it contains a progestin and an estrogen, and is triphasic because it contains three different "phases" of hormones in each pack. This contraceptive must be taken at the same time every day. Side effects may include nausea, breast tenderness, and headaches.
Tri-Norinyl and Leena are made by Watson Pharmaceuticals, Inc. Aranelle is made by Barr Pharmaceuticals, Inc. (see Generic Tri-Norinyl for more information).
How Does Tri-Norinyl Work?
Tri-Norinyl belongs to a group of birth control pills known as combined oral contraceptives, which means that it contains two different types of hormones. It contains both an estrogen (ethinyl estradiol) and a progestin (norethindrone). Combined oral contraceptives are the most common type of birth control pills used today.
Tri-Norinyl is also a "triphasic" birth control pill, which means that there are three different "phases" of pills in each pack (plus the last week of tablets that does not contain any hormones). Each phase has a different amount of the progesterone hormone. This is why it is very important to take the pills in the correct order.
Most importantly, the hormones in Tri-Norinyl prevent pregnancy by stopping ovulation (the maturation and release of eggs from the ovaries). However, it also works to prevent pregnancy in two other, minor ways. Tri-Norinyl changes the cervical mucus (the fluid of the cervix, which is the lower, narrow part of the uterus that is connected to the vagina), making it more difficult for sperm to enter the uterus. Lastly, Tri-Norinyl alters the lining of the uterus (called the endometrium), making it less receptive to an embryo.
Food and Drug Administration, Center for Drug Evaluation and Research. Electronic orange book: approved drug products with therapeutic equivalence evaluations. FDA Web site. Available at: http://www.fda.gov/cder/ob/. Accessed January 10, 2008.
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