Progestins preparations available

A large number of oral contraceptives containing estrogens or progestins (or both) are now available for clinical use (Table 40-3). These preparations vary chemically and pharmacologically and have many properties in common as well as definite differences important for the correct selection of the optimum agent. 

Only one implantable contraceptive preparation is available at present. Norgestrel, also utilized as the progestin component of some oral contraceptive preparations, is an effective suppressant of ovulation when it is released from subcutaneous implants. Intramuscular injection of large doses of medroxyprogesterone also provides contraceptive action of long duration. 

Partially purified receptor preparations have been used for production of polyclonal and monoclonal antibodies to receptors. If these antibodies are available they might be used for immunoaffinity chromatography of receptors. This procedure permits rapid isolation of highly purified receptors and has been used, e.g., for separation of different phosphorylated forms of progestin receptors [30], The right choice of a suitable reagent for elution of receptors from the immunoaffinity column in a form still able to bind the steroid was crucial in these studies. 

Esters [e.g., hydroxyprogesterone caproate (hyalutin) and MPA (DEPO-PROVERa)] are available for intramuscular administration, and MPA (PROVERA, others) and megestrol acetate (megace) may be used orally due to decreased hepatic metabolism. The 19-nor-steroids have good oral activity because the ethinyl substituent at C17 slows hepatic metabolism. Implants and depot preparations for prolonged release of synthetic progestins are widely available. 

---