Medroxyprogesterone Acetate

Absorption

Absorption of oral medroxyprogesterone acetate (MPA) varies considerably between formulations. A 1000mg oral dose reaches an average Cmax of 145-315nmol/L while a 500mg oral dose reaches an average Cmax of 33-178nmol/L with a Tmax of 1-3 hours and a lag time of half an hour. The AUC of a 500mg oral dose of MPA was 543.4-1981.1nmol*L/h depending on formulation.
Intramuscular MPA reaches a Cmax of 4.69±1.52nmol/L with a Tmax of 4.75±2.09 days and an AUC of 81.58±27.64days*nmol/L. Subcutaneous MPA reaches a Cmax of 3.83±1.56nmol/L with a T±max of 6.52±2.07 days and an AUC of 72.26±38.73days*nmol/L. However, the pharmacokinetics of MPA may also vary depending on injection site.

Toxicity

The oral LD50 in rats is >6400mg/kg and in mice is >16g/kg. The intraperitoneal LD50 in rats is >900mg/kg and in mice is >1500mg/kg. The subcutaneous LD50 in rats is >900mg/kg and in mice is>1500mg/kg.
Patients experiencing and overdose or oral medroxyprogesterone acetate (MPA) may present with nausea, vomiting, breast tenderness, dizziness, abdominal pain, drowsiness, fatigue, and withdrawal bleeding. Treat patients by stopping MPA and beginning symptomatic treatment. Patients who have been given too much of a MPA depo injection should contact a healthcare professional, hospital emergency department, or local poison control immediately.

Description

Medroxyprogesterone 17-acetate is a synthetic progestogen.,, It prevents fertilization and increases the rate of transport of eggs from the fallopian tubes to the uterus in female ferrets when administered prior to ovulation. Medroxyprogesterone 17-acetate reversibly blocks ovulation in rats when injected on the last day of diestrus. It also has anti-androgenic activity in rats, decreasing plasma testosterone (Item Nos. 15645 | ISO60154) levels via induction of hepatic testosterone reductase activity. Medroxyprogesterone 17-acetate exhibits immunosuppressive effects in vitro and in vivo, inhibiting the production of IFN-γ by CD2/CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) at concentrations ≥10 nM and extending the survival of rabbit skin allografts., Injectable formulations containing medroxyprogesterone 17-acetate have been used as contraceptives.

The Uses of Medroxyprogesterone Acetate

Medroxyprogesterone Acetate is a synthetic progesterone receptor agonist that is used to treat amenorrhea (unusual stopping of menstrual periods) and abnormal uterine bleeding.

Background

Medroxyprogesterone acetate (MPA) is a progesterone derivative that is more resistant to metabolism for improved pharmacokinetic properties. MPA can be use to treat secondary amenorrhea, endometrial hyperplasia, abnormal uterine bleeding, osteoporosis, vasomotor symptoms in menopause, vulvar and vaginal atrophy, prevent pregnancy, manage pain in endometriosis, prevent pregnancy, and is also used in palliative care for endometrial and renal carcinoma.
Medroxyprogesterone acetate was granted FDA approval on 18 June 1959.

Indications

Medroxyprogesterone acetate (MPA) oral tablets are indicated to treat secondary amenorrhea, reduce the incidence of endometrial hyperplasia in postmenopausal women, and to treat abnormal uterine bleeding due to hormonal imbalance, not organic pathology. Oral tablets containing MPA and conjugated estrogens are indicated to prevent postmenopausal osteoporosis and to treat moderate to severe menopausal symptoms such as vasomotor symptoms, vulvar atrophy, and vaginal atrophy. Subcutaneous MPA is indicated to prevent pregnancy and manage pain associated with endometriosis. Intramuscular MPA is indicated to prevent pregnancy, and at higher concentrations for palliative treatment of endometrial or renal carcinoma.

What are the applications of Application

Medroxyprogesterone 17-Acetate is a synthetic progesterone receptor agonist

Pharmacokinetics

Medroxyprogesterone acetate (MPA) inhibits gonadotropin production, reduces nuclear estrogen receptors and DNA synthesis in epithelial cells of the endometrium, and induces p53 dependant apoptosis in cancer cell lines. MPA oral tablets have a half life of 40-60 hours and other formulations can have half lives that are considerably longer, so the duration of action is long. The therapeutic window is wide as patients may take doses ranging from 5mg orally daily to 1000mg as a depo injection weekly. Long term use of MPA is associated with a reduction in bone density and patients who taking MPA during adolescence may have lower peak bone mass than untreated patients, which can also increase the risk of osteoporosis and fractures in the future.

Metabolism

Medroxyprogesterone acetate undergoes beta hydroxylation to form the metabolites 6-beta (M-2), 2-beta (M-4), and 1-beta-hydroxymedroxyprogesterone acetate (M-3). M-2 and M-4 are further metabolized to 2-beta,6-beta-dihydroxymedroxyprogesterone (M-1). M-3 is further metabolized to 1,2-dehydromedroxyprogesterone acetate (M-5).