Medroxyprogesterone acetate (MPA) is a synthetic derivative of progesterone, a naturally occurring female sex hormone. It is a potent progestin used primarily for secondary amenorrhea, abnormal uterine bleeding, and as part of hormone replacement therapy (HRT). In the Indian context, it is a widely prescribed, cost-effective option for menstrual regulation and endometrial protection.
Adult: For secondary amenorrhea: 5-10 mg daily for 5-10 days. Bleeding usually occurs within 3-7 days after discontinuation. For abnormal uterine bleeding: 5-10 mg daily for 5-10 days beginning on day 16 or 21 of the cycle. For endometrial protection with estrogen HRT: 10 mg daily for the last 10-14 days of each estrogen cycle.
Note: Take orally with or without food, preferably at the same time each day. For cyclic therapy, follow the prescribed schedule strictly (e.g., days 16-25 of a 28-day cycle). A calendar may be helpful.
Medroxyprogesterone acetate transforms proliferative endometrium into secretory endometrium. It inhibits the secretion of pituitary gonadotropins (LH and, to a lesser extent, FSH), preventing follicular maturation and ovulation at higher doses. It also exerts an anti-estrogenic effect on the endometrium, making it useful in treating estrogen-induced endometrial hyperplasia.
Pregnancy: Pregnancy Category X. Contraindicated. May cause fetal harm, including masculinization of the female fetus, congenital heart defects, and limb reduction defects. Rule out pregnancy before starting therapy.
Driving: May cause dizziness, drowsiness, or blurred vision. Patients should not drive or operate machinery until they know how the drug affects them.
| Aminoglutethimide | Decreases MPA levels by inducing hepatic metabolism. | Moderate |
| Rifampicin, Rifabutin | Significantly reduce MPA plasma levels via CYP3A4 induction, potentially reducing efficacy. | Major |
| Phenytoin, Carbamazepine, Phenobarbital | Reduce MPA plasma levels via enzyme induction. | Major |
| Ketoconazole, Itraconazole | May increase MPA levels by inhibiting CYP3A4. | Moderate |
| Warfarin and other Coumarin anticoagulants | MPA may decrease anticoagulant effect; monitor INR closely. | Moderate |
| Insulin, Oral Hypoglycemics | MPA may decrease glucose tolerance; monitor blood glucose. | Moderate |
| Cyclosporine | MPA may inhibit metabolism, increasing cyclosporine levels and toxicity risk. | Moderate |