[Parenteral contraceptive drugs: depot progestins].

Depot progestins as injectables, implantables or vaginal rings are suitable for contraception in those female patients, in which risk factors (e.g. cardiovascular risk) exclude the use of estrogen-progestin mixtures. In this paper the mode of action, indications, contraindications, advantages and disadvantages of the various methods using depot-progestins are discussed. Injectables contain either medroxyprogesterone acetate or norethistronenantate; both steroids are released slowly within a limited time interval (2 to 4 months) out of a depot. The major effect is a change of the cervical mucus. Side-effects are disturbances of the menstrual cycle (e.g. breakthrough bleedings) as well as an amenorrhea after frequent use (up to 50% of all cases). The subdermal implantables (Norplant 2 or 5) release levonorgestrel out of a depot over a time period of at least 5 years. Steroid plasma levels are lower than in those patients using a progestin-only pill. Side-effects of implantables are disturbances of the menstrual cycle (e.g. breakthrough bleeding); in patients who desire to conceive a child or suffer from undesirable side-effects the implantables can be removed at every time. The progestin releasing vaginal rings are in a stage of controlled clinical trials. The advantages depend on ethe easy mode of administration (implantation or removal). Side-effects are also breakthrough bleedings.