Norethindrone is classified as a progestin [1]. It is a synthetic form of progesterone, a naturally occurring hormone [1].
What are progestins used for?
Progestins, including norethindrone, are primarily used in hormonal birth control and in hormone therapy [1]. They work by preventing ovulation, thickening cervical mucus to block sperm, and altering the uterine lining to make implantation more difficult [1].
How does norethindrone work in birth control?
In oral contraceptives, norethindrone is typically used in combination with an estrogen or as a progestin-only pill [1]. The progestin-only pills, often referred to as "mini-pills," are a common option for women who cannot take estrogen [1]. Norethindrone's action in preventing ovulation and thickening cervical mucus contributes to its contraceptive effect [1].
What is the difference between norethindrone and other progestins?
Norethindrone is a first-generation synthetic progestin, meaning it was among the earliest developed [2]. Other progestins have been developed since, with varying structures and potencies. For example, second-generation progestins (like norgestrel and levonorgestrel) and third-generation progestins (like desogestrel and norgestimate) have different hormonal profiles and potential side effect risks [2].
When does norethindrone's patent expire?
Norethindrone is a well-established drug, and its original patents have long since expired [3]. This means generic versions of norethindrone are widely available [3].
Can generic norethindrone be used for hormone therapy?
Yes, generic norethindrone is used in hormone replacement therapy, often to counteract the effects of estrogen in women who have a uterus and are undergoing estrogen therapy [1]. It is also used to treat menstrual disorders like irregular periods or absence of menstruation [1].