Progestin

A progestin (P) is a type of medication which is used most commonly in hormonal birth control and menopausal hormone therapy. They can also be used in the treatment of gynecological conditions, to support fertility and pregnancy, to lower sex hormone levels for various purposes, and for other indications. Progestins are used alone or in combination with estrogens. They are available in a wide variety of formulations and for use by many different routes of administration. A progestin (P) is a type of medication which is used most commonly in hormonal birth control and menopausal hormone therapy. They can also be used in the treatment of gynecological conditions, to support fertility and pregnancy, to lower sex hormone levels for various purposes, and for other indications. Progestins are used alone or in combination with estrogens. They are available in a wide variety of formulations and for use by many different routes of administration. Side effects of progestins include menstrual irregularities, headaches, nausea, breast tenderness, mood changes, acne, increased hair growth, and changes in liver protein production among others. Other side effects of progestins include an increased risk of breast cancer, cardiovascular disease, and blood clots. At high dosages, progestins can cause low sex hormone levels and associated side effects like sexual dysfunction and an increased risk of bone fractures. Progestins are synthetic progestogens and have similar effects to those of the natural hormone progesterone. They act as agonists of the progesterone receptor, and have important effects in the female reproductive system (uterus, cervix, and vagina), the breasts, and the brain. In addition, many progestins also have other hormonal activities, such as androgenic, antiandrogenic, estrogenic, glucocorticoid, or antimineralocorticoid activity. They also have antigonadotropic effects and at sufficiently high dosages can strongly suppress sex hormone production. Progestins mediate their contraceptive effects both by inhibiting ovulation and by thickening cervical mucus, thereby preventing fertilization. They have functional antiestrogenic effects in certain tissues like the endometrium, and this underlies their use in menopausal hormone therapy. Progestins were first introduced for medical use in 1939. They started to be used in birth control in the 1950s. Around 60 progestins have been marketed for clinical use in humans or use in veterinary medicine. These progestins can be grouped into different classes and generations. Progestins are available widely throughout the world and are used in all forms of hormonal birth control and in most menopausal hormone therapy regimens. Progestins are used in a variety of different forms of hormonal birth control for women, including combined estrogen and progestogen forms like combined oral contraceptive pills, combined contraceptive patches, combined contraceptive vaginal rings, and combined injectable contraceptives; and progestogen-only forms like progestogen-only contraceptive pills ('mini-pills'), progestogen-only emergency contraceptive pills ('day-after pills'), progestogen-only contraceptive implants, progestogen-only intrauterine devices, progestogen-only contraceptive vaginal rings, and progestogen-only injectable contraceptives. Progestins mediate their contraceptive effects by multiple mechanisms, including prevention of ovulation via their antigonadotropic effects; thickening of cervical mucus, making the cervix largely impenetrable to sperm; preventing capacitation of sperm due to changes in cervical fluid, thereby making sperm unable to penetrate the ovum; and atrophic changes in the endometrium, making the endometrium unsuitable for implantation. They may also decrease tubal motility and ciliary action. Combined androgen and progestogen birth control methods for men have been extensively studied but have yet to be approved or marketed. Progestins are commonly used as a component of menopausal hormone therapy in women to prevent endometrial hyperplasia and increased risk of endometrial cancer from unopposed estrogen therapy. They are also used in transgender hormone therapy, including in both feminizing hormone therapy for transgender women (e.g., cyproterone acetate and medroxyprogesterone acetate to help suppress testosterone levels) and masculinizing hormone therapy in transgender men (e.g., medroxyprogesterone acetate to help suppress menses). Certain progestins, including megestrol acetate, medroxyprogesterone acetate, cyproterone acetate, and chlormadinone acetate have been used to reduce hot flashes in men with prostate cancer.