Mezest 40 mg is indicated for the palliative treatment of advanced breast cancer or endometrial cancer, including recurrent, inoperable, or metastatic disease. It should not replace standard treatments such as surgery, radiotherapy, or chemotherapy.

Mezest oral suspension is indicated for the management of anorexia, cachexia, or unexplained significant weight loss in patients with AIDS or cancer.

Megestrol acetate is a synthetic progestational and antineoplastic agent. Its exact mechanism in endometrial cancer is not fully understood, but it is believed to act by suppressing pituitary gonadotropin secretion, leading to reduced estrogen levels. In breast cancer, it may work by modifying steroid hormone activity and exerting a direct toxic effect on tumor cells. Hormone-sensitive tumor growth depends on estrogen-receptor interaction, where estrogen enters cells, binds to receptors, and influences gene transcription. Pharmacological doses of megestrol acetate reduce hormone-dependent tumor cell growth and may block estrogen’s stimulatory effects.

After oral administration, peak plasma levels occur within 2–3 hours. The half-life is approximately 33–38 hours. About 66% of the dose is excreted in urine and around 20% in feces.

Tablet:

• Breast cancer: 160 mg/day
• Endometrial carcinoma: 40-320 mg/day in divided doses.
• At least 2 months of continuous treatment is considered an adequate period for determining the efficacy of Megestrol.

Oral Suspension: The recommended adult initial dosage of Megestrol Oral Suspension is 800 mg/day (20 ml/day)

Megestrol acetate is contraindicated in patients with known hypersensitivity to the drug or any of its components. It should not be used in pregnancy or when pregnancy is suspected.

Weight gain is a common effect of megestrol acetate, especially in patients treated for breast or endometrial cancer. This is associated with increased appetite and is the basis for its use in treating anorexia, cachexia, and weight loss. The weight gain is mainly due to increased fat and body mass.

Other reported adverse effects (about 1–2%) include nausea, vomiting, edema, and breakthrough uterine bleeding. Additional effects such as gynecomastia, hearing loss, shortness of breath, heart failure, hypertension, hot flashes, mood changes, Cushing-like appearance, tumor flare (with or without high calcium levels), high blood sugar, hair loss, carpal tunnel syndrome, and skin rash have also been reported.

Serious thromboembolic events, including thrombophlebitis and pulmonary embolism (sometimes fatal), have also occurred.

Megestrol acetate is not recommended during pregnancy. Reports suggest that exposure to progestational agents in the first trimester may be associated with genital abnormalities in both male and female fetuses. Although the exact risk is not well defined, some degree of virilization of female fetuses may occur.

If exposure occurs during early pregnancy or pregnancy develops during treatment, the patient should be informed about potential fetal risks. Women of childbearing age should avoid pregnancy while taking this drug. Due to possible adverse effects, breastfeeding should be discontinued during treatment.

Megestrol Acetate should be used carefully in patients with a history of thrombophlebitis or severe liver impairment.

This medicine should be administered under specialist supervision, and patients should be monitored regularly during treatment.

Megestrol acetate may produce adrenocortical (steroid-like) effects, which should be considered during patient monitoring.

Patients with rare hereditary conditions such as galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption should not use this medicine.

Limited data are available for patients aged 65 years and older. In general, elderly patients should be treated with caution due to a higher likelihood of reduced liver, kidney, or heart function, as well as concurrent diseases or medications. Since megestrol acetate is primarily eliminated by the kidneys, patients with renal impairment may have a higher risk of toxicity, and renal function should be monitored when necessary.

Pediatric Use: Safety and effectiveness in children have not been established.

Geriatric Use: Insufficient clinical data exist to determine whether elderly patients respond differently from younger individuals. Use should be cautious due to age-related organ function decline and comorbid conditions.

No serious toxic effects were observed in studies using doses up to 1600 mg/day for six months or longer. However, post-marketing reports of overdose have included symptoms such as diarrhea, nausea, abdominal pain, shortness of breath, cough, unsteady gait, lethargy, and chest pain. There is no specific antidote for megestrol acetate overdose. Management involves supportive and symptomatic treatment.

Store below 30°C in a cool, dry place, protected from light and moisture. Keep all medicines out of the reach of children.