Medroxyprogesterone Acetate

A to Z Drug Facts

Actions Inhibits secretion of pituitary gonadotropins, thereby preventing follicular maturation and ovulation (contraceptive effect); inhibits spontaneous uterine contraction; transforms proliferative endometrium into secretory endometrium; produces antineoplastic effect in advanced endometrial or renal carcinoma. MPA is rapidly absorbed from the GI tract, and maximum MPA concentrations are obtained between 2 to 4 hr after oral administration. Administration of MPA with food increases the bioavailability of MPA. MPA is » 90% protein bound, primarily to albumin. MPA is extensively metabolized in the liver. Most MPA metabolites are excreted in the urine.

 Indications

PO

Treatment of secondary amenorrhea and abnormal uterine bleeding caused by hormonal imbalance.

Parenteral

Prevention of pregnancy; adjunctive and palliative treatment of inoperable, recurrent, and metastatic endometrial or renal carcinoma.

Treatment of menopausal symptoms; stimulation of respiration in obstructive sleep apnea.

 Contraindications Hypersensitivity to progestins; current or history of thrombophlebitis, thromboembolic disorders, cerebrovascular disease, or cerebral hemorrhage; impaired liver function; breast cancer; undiagnosed vaginal bleeding; missed abortion; diagnostic test for pregnancy.

 Route/Dosage

Secondary Amenorrhea

ADULTS: PO 5 to 10 mg/day for 5 to 10 days.

Abnormal Uterine Bleeding

ADULTS: PO 5 to 10 mg/day for 5 to 10 days beginning on 16th or 21st day of menstrual cycle.

Contraceptive

ADULTS: IM 150 mg q 3 mo.

Endometrial or Renal Carcinoma

ADULTS: IM 400 to 1000 mg weekly initially; maintenance: 400 mg/mo.

Interactions

Aminoglutethimide

May increase metabolism and decrease effect of medroxyprogesterone.

Lab Test Interferences Endocrine, coagulation (increased amounts of some clotting factors), thyroid and LFT results may be affected by progestins; may alter metyrapone test results; may decrease glucose tolerance.

 Adverse Reactions

CARDIOVASCULAR: Thrombophlebitis; edema. CNS: Depression; headache; nervousness; dizziness; insomnia; fatigue; somnolence. DERMATOLOGIC: Rash; acne; melasma; chloasma; alopecia; hirsutism; photosensitivity. GI: Abdominal pain or discomfort; nausea. GU: Breakthrough bleeding; spotting; change in menstrual flow; amenorrhea; decrease in libido; changes in cervical erosion and secretions. HEPATIC: Cholestatic jaundice. RESPIRATORY: Pulmonary embolism. OTHER: Breast tenderness; masculinization of female fetus; edema; weight changes, especially weight gain; anaphylactoid reactions; bone mineral density changes, increasing risk of osteoporosis; hyperglycemia.

 Precautions

Pregnancy: Category X. Lactation: Excreted in breast milk. Conception: Has prolonged contraceptive effect, which may delay time to potential conception once therapy is discontinued. Contraception: If period between injections is > 14 days, determine that patient is not pregnant before administering drug. Fluid retention: Use with careful observation when conditions that might be affected by this factor are present (eg, asthma, cardiac or renal dysfunction, epilepsy). Mental depression: Carefully observe patients with history of depression. Ophthalmic effects: Discontinue medication if there are any sudden changes in vision, sudden onset of proptosis, diplopia, migraine, papilledema, or retinal vascular lesions.

 Administration/Storage

• Administer oral dose on same days of month as prescribed.
• Give medication with food if GI upset occurs.
• Parenteral dosage form is for IM administration only. Inject deeply into large muscle.
• Shake vial vigorously prior to IM administration.
• Rotate site of IM administration and observe for redness and warmth at injection site.
• When using contraceptive injection, give during first 5 days after onset of normal menstrual period or within 5 days postpartum if not breastfeeding or at 6 wk postpartum if breast feeding.
• Store at room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Monitor serum glucose in patients with diabetes.
• Monitor results of LFTs throughout therapy.
• Assess patient's weight daily. Notify health care provider of > 5 lb gain.
• Include breast and pelvic examination and Papanicolaou smear in pretherapy physical assessment.
• Assess BP at beginning of therapy and periodically during treatment.
• Assess fluid and respiratory status and notify health care provider of any changes.
• Notify health care provider of pain in calves accompanied by swelling, warmth, and redness; sudden severe headache; visual disturbances; numbness in extremities; signs of depression; signs of liver dysfunction (eg, dark urine, jaundice).
• Monitor mental status: affect, mood, depression, behavioral changes.
• Monitor I&O.

 Patient/Family Education

• Caution patient that this medication must not be taken during pregnancy or when pregnancy is possible. Advise patient to use reliable form of birth control while taking this drug.
• Advise patient to take tablets with food if GI upset occurs.
• Explain significance of irregular menstrual cycles, breakthrough bleeding, or change in menstrual flow, and tell patient to notify health care provider of heavy or continuous menstrual flow.
• Caution patient to avoid prolonged exposure to sunlight and other sources of ultraviolet light and to use sunscreen and wear protective clothing to avoid photosensitivity reaction.
• Encourage patients with diabetes to monitor blood glucose more frequently until effect on diabetes control is determined.
• Tell patient to notify health care provider of pain in calves with swelling, warmth, or redness; sudden severe headache; visual disturbances; numbness in extremities.
• Instruct patient to report the following symptoms to health care provider: breast abnormalities, vaginal bleeding, edema, jaundice, dark urine, clay-colored stools, dyspnea, chest pain, suspected pregnancy.
• Remind patient using agent for contraception that doses must be administered q 3 mo to ensure effectiveness.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts