Megestrol Acetate is used in anorexia, cachexia or a significant weight loss. Megestrol Acetate is also indicated for the palliative treatment of advanced carcinoma of the breast (i.e. recurrent, inoperable or metastatic diseases). It should not be used in lieu of currently accepted procedures such as surgery, radiation or chemotherapy.
Synthetic progestational anticancer drug
Megestrol Acetate is a synthetic, antineoplastic and progestational drug. While the precise mechanism by which Megestrol Acetate produces its antineoplastic effects against endometrial carcinoma is unknown at the present time, inhibition of pituitary gonadotrophin production and resultant decrease in estrogen secretion may be factors. The antineoplastic action of megestrol acetate on carcinoma of the breast is effected by modifying the action of other steroid hormones and by exerting a direct cytotoxic effect on tumor cells. In metastatic cancer, hormone receptors may be present in some tissues but not others. The receptor mechanism is a cyclic process whereby estrogen produced by the ovaries enters the target cell, forms a complex with cytoplasmic receptor and is transported into the cell nucleus. There it induces gene transcription and leads to the alteration of normal cell functions. Pharmacologic doses of megestrol acetate not only decrease the number of hormone-dependent human breast cancer cells but also are capable of modifying and abolishing the stimulatory effects of estrogen on these cells.
Estimates of plasma levels of Megestrol Acetate are dependent on the measurement method used. Peak plasma concentrations occur 2 to 3 hours after a single oral dose 160 mg tablets. The plasma half-life of Megestrol Acetate is 33 to 38 hours. Approximately 66% of an administered dose is excreted in the urine and approximately 20% in the faeces.
For the following indications, at least two months of continuous treatment is considered an adequate period for determining the efficacy of megestrol acetate tablets. For palliative or adjunctive treatment of breast carcinoma: 160 mg or 125 mg/m2 daily (40 mg q.i.d. or 160 mg q.d.) For endometrial carcinoma: 80 - 320 mg or 62.5 - 250 mg/m2 daily in divided doses (40 - 80 mg one to four times daily or one to two 160 mg tablets daily). For palliative treatment of hormone responsive advanced (Stage D2) carcinoma of the prostate: 120 mg (93.8 mg/m2) as a single daily dose in combination with diethylstilbestrol tablet, 0.1 mg. For anorexia, cachexia, or significant weight loss in patients with cancer: usual adult dose: 400 to 800 mg as a single daily dose. The recommended adult initial dosage of megestrol acetate oral suspension is 625 mg/day (5 mL/day or one teaspoon daily). Shake container well before using
With medicine: Possible interactions of Megestrol Acetate with concomitant medications have not been investigated.
With food and others: Estrogens and Progestogens may cause fluid retention, particularly when given in high dosages or for prolonged periods. Therapy with these agents should be administered cautiously in patients who have preexisting problems with excess fluid.
Allergy to Megestrol acetate or any of the excipients. Women of child bearing potential should be advised to avoid becoming pregnant. History of thrombophlebitis, mild to moderate hepatic impairment, risk of fluid retention, history of depression, diabetes, hypertension, renal or cardiac dysfunction.
Side Effects: Nausea, vomiting, edema occur in approximately 1% to 2% of patients. Dyspnea, pain, hypertension, hot flashes, sweating mood changes, hyperglycemia, alopecia, asthenia, malaise, lethargy, rash, flatulence, diarrhoea and impotence have been reported. Constipation and urinary frequency have been reported in patients who received high doses of Megestrol acetate in clinical trials. Adverse effects: Thromboembolic phenomena: Thromboembolic phenomena including thrombophlebitis and pulmonary embolism (in some cases fatal) have been reported. Other adverse reactions: Breakthrough uterine bleeding occur in approximately 1% to 2% of patients. Heart failure, cushingoid facies, tumor flare (with or without hypercalcemia), carpal tunnel syndrome and urticaria have been reported.
Pregnancy category D. Megestrol Acetate can cause fetal abnormalities and risks, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits. Nursing mothers: Very small amounts (approximately 0.1%) are excreted in mother's milk. It is however, not known whether these amounts exert any harmful effect on the newborn. Because of the potential for adverse effects on the new born, nursing should be discontinued during treatment with Megestrol Acetate.
No acute toxicological effects have resulted from studies involving megestrol acetate administered in dosages as high as 1600 mg/day for six months or more. Reports of overdose have also been received in the postmarketing setting. Signs and symptoms reported in the context of overdose included diarrhoea, nausea, abdominal pain, shortness of breath, cough, unsteady gait, listiessness, and chest pain. There is no specific antidote for overdose with Megestrol Acetate. In case of overdose, appropriate supportive measures should be taken.
Store in a cool (below 30°C) and dry place, away from light & moisture. Keep all medicines out of reach of children.
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