Medically reviewed on Nov 15, 2018
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- Megestrol Acetate
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Suspension, Oral, as acetate:
Megace ES: 625 mg/5 mL (150 mL) [contains alcohol, usp, sodium benzoate; lemon-lime flavor]
Megace Oral: 40 mg/mL (240 mL [DSC]) [lemon-lime flavor]
Generic: 40 mg/mL (10 mL, 240 mL, 480 mL); 400 mg/10 mL (10 mL); 625 mg/5 mL (150 mL)
Tablet, Oral, as acetate:
Generic: 20 mg, 40 mg
Brand Names: U.S.
- Megace ES
- Megace Oral [DSC]
- Antineoplastic Agent, Hormone
- Appetite Stimulant
A synthetic progestin with antiestrogenic properties which disrupt the estrogen receptor cycle. Megestrol interferes with the normal estrogen cycle and results in a lower LH titer. May also have a direct effect on the endometrium. Megestrol is an antineoplastic progestin thought to act through an antileutenizing effect mediated via the pituitary. May stimulate appetite by antagonizing the metabolic effects of catabolic cytokines.
Hepatic (to free steroids and glucuronide conjugates)
Urine (57% to 78%; 5% to 8% as metabolites); feces (8% to 30%) within 10 days
Onset of Action
Breast or endometrial cancer: At least 2 months of continuous therapy; Weight gain: 2 to 4 weeks
Time to Peak
Serum: Suspension: 5 hours; Tablet: 2.2 hours (range: 1 to 3 hours)
Suspension: 20 to 50 hours; Tablet: Mean: 34.2 hours (range: 13 to 105 hours)
Use: Labeled Indications
Anorexia or cachexia: Suspension: Treatment of anorexia, cachexia, or unexplained significant weight loss in patients with AIDS
Limitations of use: Treatment of AIDS-related weight loss should only be initiated after addressing the treatable causes (eg, malignancy, infection, malabsorption, endocrine disease, renal disease, psychiatric disorder) for weight loss. Megestrol is not intended to prevent weight loss.
Breast cancer: Tablet: Treatment (palliative) of advanced breast cancer
Endometrial cancer: Tablet: Treatment (palliative) of advanced endometrial carcinoma
Off Label Uses
Treatment of cancer-related cachexia
Data from randomized, placebo controlled studies [Loprinzi 1990], [Vadell 1998]; support the use of megestrol to promote weight gain in cachectic patients with cancer. A meta-analysis of megestrol for the management of anorexia/cachexia showed benefit with the use of megestrol; higher doses were associated with more weight gain, however, data was insufficient to determine an optimal dose [Ruiz Garcia 2013]. Data from dose finding studies suggest higher doses are associated with higher weight gain [Beller 1997], [Loprinzi 1993].
Hypersensitivity to megestrol or any component of the formulation; known or suspected pregnancy (suspension).
Documentation of allergenic cross-reactivity for progestins is limited. However, because of similarities in chemical structure and/or pharmacologic actions, the possibility of cross-sensitivity cannot be ruled out with certainty.
Note: Megace ES suspension is not equivalent to other formulations on a mg-per-mg basis.
Anorexia or cachexia associated with AIDS: Oral: Suspension: Initial: 625 mg daily (of the 125 mg/mL suspension) or 800 mg daily (of the 40 mg/mL suspension); daily doses of 400 mg to 800 mg have been found to be effective
Breast cancer, advanced: Oral: Tablet: 160 mg per day in divided doses of 40 mg 4 times daily for at least 2 months
Endometrial cancer, advanced: Oral: Tablet: 40 to 320 mg daily in divided doses for at least 2 months
Cancer-related cachexia (off-label use): Oral: Doses ranging from 160 to 800 mg per day were effective in achieving weight gain, higher doses (>160 mg) were associated with more weight gain (Beller 1997; Loprinzi 1990; Loprinzi 1993; Vadell 1998); based on a meta-analysis, an optimal dose has not been determined (Ruiz Garcia 2013)
Use with caution; refer to adult dosing.
Dosing: Renal Impairment
There are no dosage adjustments provided in the manufacturer's labeling; however, the urinary excretion of megestrol acetate is substantial, use with caution.
Dosing: Hepatic Impairment
There are no dosage adjustments provided in the manufacturer's labeling.
Oral: Shake suspension well before use.
The 625 mg/5 mL suspension may be administered without regard to meals.
Suspension: Store at 15°C to 25°C (59°F to 77°F); protect from heat. Store/dispense in a tight container.
Tablet: Store at 15°C to 30°C (59°F to 86°F); protect from light. Protect from temperatures above 40°C (104°F).
Anticoagulants: Progestins may diminish the therapeutic effect of Anticoagulants. More specifically, the potential prothrombotic effects of some progestins and progestin-estrogen combinations may counteract anticoagulant effects. Management: Carefully weigh the prospective benefits of progestins against the potential increased risk of procoagulant effects and thromboembolism. Use is considered contraindicated under some circumstances. Refer to related guidelines for specific recommendations. Consider therapy modification
Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy
C1 inhibitors: Progestins may enhance the thrombogenic effect of C1 inhibitors. Monitor therapy
Choline C 11: Antiandrogens may diminish the therapeutic effect of Choline C 11. Monitor therapy
Dofetilide: Megestrol may increase the serum concentration of Dofetilide. Avoid combination
Herbs (Progestogenic Properties) (eg, Bloodroot, Yucca): May enhance the adverse/toxic effect of Progestins. Monitor therapy
Indium 111 Capromab Pendetide: Antiandrogens may diminish the diagnostic effect of Indium 111 Capromab Pendetide. Avoid combination
Pomalidomide: Progestins may enhance the thrombogenic effect of Pomalidomide. Management: Canadian pomalidomide labeling recommends caution with use of hormone replacement therapy and states that hormonal contraceptives are not recommended. US pomalidomide labeling does not contain these specific recommendations. Consider therapy modification
Ulipristal: Progestins may diminish the therapeutic effect of Ulipristal. Ulipristal may diminish the therapeutic effect of Progestins. Management: Ulipristal for uterine fibroids (Canadian indication): avoid progestins within 12 days of stopping ulipristal; as emergency contraceptive (U.S. indication): avoid progestins within 5 days of stopping ulipristal. Avoid combination
Frequency not always defined.
Cardiovascular: Hypertension (4% to 8%), cardiomyopathy (1% to 3%), chest pain (1% to 3%), edema (1% to 3%), palpitations (1% to 3%), peripheral edema (1% to 3%), cardiac failure
Central nervous system: Headache (3% to 10%), pain (4% to 6%, similar to placebo), insomnia (1% to 6%), abnormality in thinking (1% to 3%), confusion (1% to 3%), convulsions (1% to 3%), depression (1% to 3%), hypoesthesia (1% to 3%), neuropathy (1% to 3%), paresthesia (1% to 3%), carpal tunnel syndrome, lethargy, malaise, mood changes
Dermatologic: Skin rash (6% to 12%), alopecia (1% to 3%), dermatological disease (1% to 3%), diaphoresis (1% to 3%), pruritus (1% to 3%), vesicobullous dermatitis (1% to 3%)
Endocrine & metabolic: Hyperglycemia (6%), decreased libido (1% to 5%), albuminuria (1% to 3%), gynecomastia (1% to 3%), increased lactate dehydrogenase (1% to 3%), adrenocortical insufficiency, amenorrhea, Cushing's syndrome, diabetes mellitus, hot flash, HPA-axis suppression, hypercalcemia, weight gain (not attributed to edema or fluid retention)
Gastrointestinal: Diarrhea (10%, similar to placebo), flatulence (6% to 10%), vomiting (4% to 6%), nausea (4% to 5%), dyspepsia (2% to 3%), abdominal pain (1% to 3%), constipation (1% to 3%), oral moniliasis (1% to 3%), sialorrhea (1% to 3%), xerostomia (1% to 3%)
Genitourinary: Impotence (4% to 14%), urinary incontinence (1% to 3%), urinary tract infection (1% to 3%), urinary frequency (1% to 2%), breakthrough bleeding
Hematologic & oncologic: Leukopenia (1% to 3%), sarcoma (1% to 3%), tumor flare
Hepatic: Hepatomegaly (1% to 3%)
Infection: Candidiasis (1% to 3%), herpes virus infection (1% to 3%), infection (1% to 3%)
Neuromuscular & skeletal: Weakness (5% to 6%)
Ophthalmic: Amblyopia (1% to 3%)
Respiratory: Cough (1% to 3%), dyspnea (1% to 3%), pharyngitis (1% to 3%), pulmonary disorder (1% to 3%), pneumonia (1%), hyperventilation
Miscellaneous: Fever (1% to 6%)
Postmarketing and/or case reports: Decreased glucose tolerance, thromboembolic phenomena (including deep vein thrombosis, pulmonary embolism, thrombophlebitis)
Concerns related to adverse effects:
• Adrenal suppression: May suppress hypothalamic-pituitary-adrenal (HPA) axis during chronic administration; consider the possibility of adrenal suppression in any patient receiving or being withdrawn from chronic therapy when signs/symptoms suggestive of hypoadrenalism are noted (during stress or in unstressed state). Laboratory evaluation and replacement/stress doses of rapid-acting glucocorticoid should be considered.
• Cushing syndrome: Has been reported with long-term use.
• AIDS-related cachexia: The effects on HIV viral replications are unknown.
• Diabetes: New-onset diabetes mellitus and exacerbation of preexisting diabetes have been reported with long-term use.
• Thromboembolism: Use with caution in patients with a history of thromboembolic disease.
• Females: Vaginal bleeding or discharge may occur.
Concurrent drug therapy issues:
• Drug-drug interactions: Potentially significant drug interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.
Dosage form specific issues:
• Benzyl alcohol and derivatives: Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer’s labeling.
• Concentrated suspension: Megace ES suspension in not equivalent to other formulations on a mg-per-mg basis; Megace ES suspension 625 mg/5 mL is equivalent to megestrol acetate suspension 800 mg/20 mL.
Observe for signs of thromboembolic events; blood pressure, weight; serum glucose
Pregnancy Risk Factor
D (tablet) / X (suspension)
Adverse events were demonstrated in animal reproduction studies. May cause fetal harm if administered to a pregnant woman. Use during pregnancy is contraindicated (suspension) and appropriate contraception is recommended in women who may become pregnant. In clinical studies, megestrol was shown to cause breakthrough vaginal bleeding in women.
• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience increased hunger, insomnia, hair loss, hot flashes, sweating a lot, diarrhea, or flatulence. Have patient report immediately to prescriber signs of high blood sugar (confusion, fatigue, increased thirst, increased hunger, polyuria, flushing, fast breathing, or breath that smells like fruit), signs of Cushings disease (weight gain in upper back or abdomen; moon face; severe headache; or slow healing), signs of adrenal gland problems (severe nausea, vomiting, severe dizziness, passing out, muscle weakness, severe fatigue, mood changes, lack of appetite, or weight loss), severe nausea, vomiting), shortness of breath, excessive weight gain, swelling of arms or legs, abnormal vaginal bleeding, mood changes, sexual dysfunction, decreased libido, severe headache, severe dizziness, passing out, severe loss of strength and energy, vision changes, or signs of blood clots (numbness or weakness on one side of the body; pain, redness, tenderness, warmth, or swelling in the arms or legs; change in color of an arm or leg; angina; shortness of breath; tachycardia; or coughing up blood) (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.
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- Drug class: hormones/antineoplastics