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Megestrol Acetate is a synthetic derivative of progesterone with an antiestrogenic activity. Megestrol binds to and activates nuclear receptors which subsequently bind to and activate target genes for transcription. As an antiestrogen, this agent may inhibit the growth-stimulating effects of estrogen on estrogen-sensitive tumor cells. In addition, megestrol stimulates appetite in cachectic subjects.
Megestrol acetate is a progestogen with actions and uses similar to those of the progestogens in general. Megestrol acetate also has anti-androgenic properties. It is given by mouth in the palliative treatment or as an adjunct to other therapy in endometrial carcinoma and in breast cancer. Megestrol acetate has been approved to treat anorexia and cachexia. (From Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1995)
Mechanism of Action of Megestrol Acetate
Megestrol acetate shares the actions of the progestins: induction of secretory changes in the endometrium, increase in basal body temperature, pituitary inhibition, and production of withdrawal bleeding in the presence of estrogen. In animals, the drug suppresses ovulation and produces antigonadotrophic, antiuterotrophic and antiandrogenic/antimyotrophic effects. It has slight glucocorticoid activity and a very slight degree of mineralocorticoid activity. Megestrol acetate has no estrogenic, androgenic, or anabolic activity.
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The precise mechanism by which megestrol acetate produces effects in anorexia and cachexia is unknown at the present time, but its progestin antitumor activity may involve suppression of luteinizing hormone by inhibition of pituitary function. Studies also suggest that the megestrol’s weight gain effect is related to its appetite-stimulant or metabolic effects rather than its glucocorticoid-like effects or the production of edema. It has also been suggested that megestrol may alter metabolic pathways via interferences with the production or action of mediators such as cachectin, a hormone that inhibits adipocyte lipogenic enzymes.
Megestrol Acetate Indications
- For the treatment of anorexia, cachexia, or an unexplained, significant weight loss in patients with a diagnosis of acquired immunodeficiency syndrome (AIDS). Also used for the palliative management of recurrent, inoperable, or metastatic breast cancer, endometrial cancer, and prostate cancer in Canada and some other countries.
- Breast Cancer-Palliative
- Endometrial Carcinoma
- Abnormal Uterine Bleeding
- Anorexia
- AIDS-Related Wasting
- Breast Cancer, Palliative
- Cachexia
- Endometrial Cancer
- Endometrial Hyperplasia
- Hot Flashes
- Weight Loss
Therapeutic Uses
- Antineoplastic Agents, Hormonal; Progestational Hormones, Synthetic
- Megestrol Acetate Tablets USP is indicated for the palliative treatment of advanced carcinoma of the breast or endometrium (ie, recurrent, inoperable, or metastatic disease). It should not be used in lieu of currently accepted procedures such as surgery, radiation, or chemotherapy.
- Megestrol Acetate Oral Suspension USP is indicated for the treatment of anorexia, cachexia, or an unexplained, significant weight loss in patients with a diagnosis of acquired immunodeficiency syndrome (AIDS).
- Anorexia is a common disorder in patients treated with regular hemodialysis and is a contributing factor to malnutrition. The aim of this study was to evaluate the effectiveness of megestrol acetate, an appetite stimulant used in cancer patients, as a treatment for anorexia in dialysis patients.
Contraindications of Megestrol Acetate
- Severe infection
- insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।" data-rx-term="diabetes" data-rx-definition="Diabetes is a condition where blood sugar stays too high because insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।">Diabetes
- Anemia
- Decreased Function of the Adrenal Gland
- High blood pressure
- Chronic heart failure
- Obstruction of a Blood Vessel by a Blood Clot
- High Blood Sugar
- Decreased Blood Platelets
- Severely Decreased Platelets
- Decreased Neutrophils a Type of White Blood Cell
- Peripheral pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।" data-rx-term="neuropathy" data-rx-definition="Neuropathy means nerve damage or irritation causing pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।">neuropathy
- Disease of Inadequate Blood Flow to the Heart Muscle
- Abnormal heart rhythm
- Heart Disease
- Liver problems
- Severe liver disease
- High Amount of jaundice. সহজ বাংলা: জন্ডিসে বাড়তে পারে এমন হলুদ রঞ্জক।" data-rx-term="bilirubin" data-rx-definition="Bilirubin is a yellow pigment that can build up in jaundice. সহজ বাংলা: জন্ডিসে বাড়তে পারে এমন হলুদ রঞ্জক।">Bilirubin in the Blood
- Abnormal liver function tests
- Pregnancy
- A mother who is producing milk and breastfeeding
- Severely Decreased Levels of Neutrophils in the Blood
Megestrol Acetate Dosage
Strengths: 40 mg/mL; 20 mg; 40 mg; 625 mg/5 mL
Breast Cancer-Palliative
- Megestrol tablets are indicated for use in the palliative treatment of advanced carcinoma of the breast: 160 mg/day (40 mg of oral tablets four times a day)
Endometrial Carcinoma
- Megestrol tablets are indicated for use in the palliative treatment of advanced carcinoma of the endometrium: 40 to 320 mg/day of oral tablets in divided doses
Anorexia
- Megestrol oral suspension is indicated for use in the treatment of anorexia at a dose of 800 mg/day.
- Alternatively, 625 mg/5 mL of the concentrated formula (Megace ES formula) may be given.
- Note: 800 mg/20 mL of the regular formula is equivalent to 625 mg/ 5 mL of the concentrated formula.
Cachexia
- Megestrol oral suspension is indicated for use in the treatment of cachexia at a dose of 800 mg/day.
- Alternatively, 625 mg/5 mL of the concentrated formula (Megace ES formula) may be given.
- Note: 800 mg/20 mL of the regular formula is equivalent to 625 mg/ 5 mL of the concentrated formula.
Weight Loss
- Megestrol oral suspension is indicated for use in the treatment of unexplained, significant weight loss in patients with a diagnosis of acquired immunodeficiency syndrome (AIDS) at a dose of 800 mg/day.
- Alternatively, 625 mg/5 mL of the concentrated formula (Megace ES formula) may be given.
- Note: 800 mg/20 mL of the regular formula is equivalent to 625 mg/ 5 mL of the concentrated formula.
Abnormal Uterine Bleeding
- 5 to 10 mg/day for 5 to 10 days
Side Effects of Megestrol Acetate
The Most Common
- Abdominal or stomach pain or tenderness
- diarrhea
- symptoms of heart problems (e.g., shortness of breath, swelling of the ankles or feet, chest pain, irregular heartbeat)
- symptoms of liver problems (e.g., nausea, vomiting, abdominal pain, yellowing of the skin and eyes, itchy skin, dark urine)
- symptoms of lung problems (e.g., shortness of breath or difficulty breathing, chest pain, cough)
- symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; swelling of the face, mouth, tongue, or throat)
- signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
More Common
- Acid or sour stomach
- back pain
- belching
- cracked lips
- diarrhea (mild)
- dry skin
- heartburn
- indigestion
- pain in the arms or legs
- redness, swelling, or painful skin
- scaling of the skin on the hands and feet
- sores, ulcers, or white spots on the lips, tongue, or the inside of the mouth
Rare
- Black, tarry stools
- body aches or pain
- burning, numbness, tingling, or painful sensations
- burning pain on urination
- chest pain
- chills
- cough
- difficult or labored breathing
- ear congestion
- fever
- headache
- loss of voice
- lower back or side pain
- nasal congestion
- painful or difficult urination
- pale skin
- red, swelling, or painful skin
Drug Indications of Megestrol Acetate
Megestrol Acetate may interact with following drugs, supplements & may change the efficacy of drugs
- calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
- carbamazepine
- cyclosporine
- diabetes medications (e.g., chlorpropamide, glipizide, glyburide, insulin, metformin, nateglinide, rosiglitazone)
- corticosteroids (e.g., prednisone, dexamethasone)
- cyclosporine
- dexamethasone
- domperidone
- everolimus
- “gliptin” diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
- “glitazone” diabetes medications
- hydrocortisone
- loperamide
- macrolide antibiotics (e.g., clarithromycin, erythromycin)
- methotrexate
- metronidazole
- mirabegron
- phenobarbital
- phenytoin
- prazosin
- progesterone
- propranolol
- protein kinase inhibitors (e.g., pazopanib, sunitinib)
- quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
- “statin” anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
- tacrolimus
- testosterone and androgens(for men taking megestrol to treat prostate cancer)
- estrogen (for women taking megestrol for breast or endometrial cancer)
- ulipristal
- warfarin
Pregnancy Category
US FDA Pregnancy Category: X
Pregnancy
Megestrol acetate is not recommended for use during the first 4 months of pregnancy. Women should use effective birth control when taking megestrol. If you become pregnant while taking megestrol, tell your doctor right away.
Lactation
This medication may pass into breast milk. If you are a breast-feeding mother and are taking megestrol acetate, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding. The safety and effectiveness of using this medication have not been established for children.
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