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Sunday, August 17, 2025

Medroxyprogesterone tablets


Overview

Medroxyprogesterone acetate (MPA) is a synthetic progestogen widely used in gynecology and endocrinology. It is a derivative of progesterone with high oral bioavailability and potent progestational effects. MPA tablets are indicated for several conditions related to hormonal imbalance, menstrual disorders, endometrial protection, and hormone replacement therapy (HRT).

Unlike depot medroxyprogesterone (injectable), which is mainly used for long-acting contraception, oral medroxyprogesterone tablets are used at lower doses for regulation of menstruation, treatment of endometriosis, and as part of combined therapy with estrogens in postmenopausal women to reduce the risk of endometrial hyperplasia.

Pharmacological Class and Formulations

  • Class: Synthetic progestogen (progestin)

  • ATC Code: G03DA02

  • Formulations (oral tablets):

    • 2.5 mg

    • 5 mg

    • 10 mg

Mechanism of Action

  • Acts on progesterone receptors in the endometrium, hypothalamus, and pituitary.

  • Suppresses gonadotropin release (FSH and LH) → inhibits ovulation at higher doses.

  • Transforms proliferative endometrium into a secretory state, stabilizing the uterine lining.

  • Reduces estrogen-driven endometrial hyperplasia when combined with estrogen in HRT.

  • Antigonadotropic effects at higher doses reduce estrogen production and help in endometriosis management.

Pharmacokinetics

  • Absorption: Rapidly absorbed orally.

  • Distribution: Widely distributed; protein binding ~90%.

  • Metabolism: Extensive hepatic metabolism.

  • Elimination: Urinary excretion of metabolites.

  • Half-life: 12–17 hours (supports once-daily dosing).

Clinical Indications

Gynecological and Endocrine Uses

  1. Secondary amenorrhea (to induce withdrawal bleeding).

  2. Abnormal uterine bleeding (AUB) due to hormonal imbalance.

  3. Endometriosis (pain relief and suppression of endometrial lesions).

  4. Prevention of endometrial hyperplasia during estrogen replacement therapy in postmenopausal women.

  5. Dysfunctional uterine bleeding (non-structural).

Contraindications

  • Known hypersensitivity to medroxyprogesterone or tablet components.

  • Undiagnosed abnormal genital bleeding.

  • Known, suspected, or history of breast cancer (unless specifically indicated).

  • Active or recent thromboembolic disorders.

  • Active liver disease or hepatic dysfunction.

  • Pregnancy (not for use during pregnancy; may cause fetal harm).

Precautions

  • Cardiovascular risk: Increased risk of thromboembolism, stroke, and myocardial infarction with long-term progestin/estrogen therapy.

  • Breast cancer risk: Long-term combined HRT may increase risk.

  • Bone health: Unlike depot injections, oral MPA at therapeutic doses has less effect on bone mineral density.

  • Hepatic impairment: Use with caution; metabolism may be impaired.

  • Psychiatric: Monitor mood; progestins may affect mood in susceptible individuals.

Adverse Effects

Common

  • Weight gain

  • Headache, dizziness

  • Breast tenderness

  • Nausea, bloating

  • Menstrual changes (spotting, breakthrough bleeding, amenorrhea)

Less Common

  • Acne, hirsutism, alopecia

  • Mood changes, depression, insomnia

  • Edema, fluid retention

Rare but Serious

  • Thromboembolic events (DVT, PE)

  • Stroke, myocardial infarction

  • Severe hepatic dysfunction

  • Hypersensitivity reactions

Drug Interactions

  • CYP3A4 inducers (rifampin, carbamazepine, phenytoin): reduce effectiveness.

  • CYP3A4 inhibitors (ketoconazole, clarithromycin): may increase plasma levels.

  • Warfarin and anticoagulants: potential interaction, monitor INR.

  • Other hormonal therapies: interactions depend on regimen.

Dosage (Oral Tablets)

Abnormal Uterine Bleeding / Secondary Amenorrhea

  • 5–10 mg once daily for 5–10 days, beginning on day 16 or 21 of the cycle.

  • Withdrawal bleeding typically occurs within 3–7 days after stopping therapy.

Endometriosis

  • 10 mg three times daily for 90 consecutive days (longer courses may be used under specialist supervision).

Prevention of Endometrial Hyperplasia (with Estrogen in HRT)

  • 2.5–10 mg once daily for 12–14 days of each 28-day estrogen cycle, OR

  • 5 mg daily continuously in continuous combined regimens.

Pediatric Use

  • Not recommended for premenarchal girls; use only under specialist guidance in adolescents with menstrual disorders.

Monitoring

  • Baseline: Rule out pregnancy before initiation; evaluate liver function and cardiovascular risk.

  • During therapy:

    • Monitor blood pressure.

    • Assess menstrual response and cycle regularity.

    • Monitor mood and weight.

    • Long-term HRT: breast exams, mammography, and endometrial surveillance if abnormal bleeding occurs.

Patient Counseling Points

  • Take tablets at the same time each day.

  • Report any unexpected vaginal bleeding.

  • Report symptoms of blood clots (leg pain, swelling, chest pain, shortness of breath).

  • May cause dizziness — use caution with driving/machinery.

  • Inform healthcare provider of all medications, particularly anticonvulsants and antibiotics.

  • Not for use during pregnancy; contraception should be used if pregnancy is not desired.




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