Megestrol Acetate 40mg Tablets
It is used to help raise feelings of hunger.It is used to treat endometrial or breast cancer.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antineoplastic agent; Progestin; Appetite stimulant
Pharmacologic Class
Synthetic progestin
Pregnancy Category
Category X
FDA Approved
Sep 1971
DEA Schedule
Not Controlled
Overview
What is this medicine?
Megestrol acetate is a man-made hormone similar to progesterone. It is used to help people with certain medical conditions gain weight or to treat certain types of cancer, like breast or uterine cancer.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, it's essential to use it as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication exactly as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the quality and safety of your medication, store it at room temperature in a dry location, avoiding bathrooms and areas prone to moisture. Keep all medications in a secure place, out of the reach of children and pets, to prevent accidental ingestion or exposure.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, it's essential to use it as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication exactly as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the quality and safety of your medication, store it at room temperature in a dry location, avoiding bathrooms and areas prone to moisture. Keep all medications in a secure place, out of the reach of children and pets, to prevent accidental ingestion or exposure.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take this medicine exactly as prescribed by your doctor.
- Do not stop taking this medicine suddenly, especially if you have been on it for a long time, without talking to your doctor, as it can cause withdrawal symptoms.
- Maintain a balanced diet as recommended by your healthcare provider.
- Report any unusual bleeding, swelling, or pain to your doctor immediately.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
For anorexia, cachexia, or unexplained significant weight loss in AIDS patients: 800 mg once daily (e.g., 20 x 40mg tablets). For breast cancer: 160 mg/day (e.g., 4 x 40mg tablets) in divided doses. For endometrial cancer: 40-320 mg/day (e.g., 1-8 x 40mg tablets) in divided doses.
Dose Range:
40 - 800 mg
Condition-Specific Dosing:
anorexia_cachexia_aids:
800 mg once daily
breast_cancer:
160 mg/day in divided doses
endometrial_cancer:
40-320 mg/day in divided doses
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment recommended, use with caution.
Moderate:
No specific adjustment recommended, use with caution.
Severe:
No specific adjustment recommended, use with caution; monitor for adverse effects.
Dialysis:
Not available; megestrol acetate is highly protein bound and not significantly removed by dialysis.
Hepatic Impairment:
Mild:
No specific adjustment recommended.
Moderate:
No specific adjustment recommended.
Severe:
No specific adjustment recommended; use with caution due to potential for altered metabolism.
Pharmacology
Mechanism of Action
Megestrol acetate is a synthetic progestin. Its antineoplastic effects are thought to be mediated through an anti-luteinizing hormone effect, direct cytotoxicity, and anti-estrogenic effects (e.g., downregulation of estrogen receptors, inhibition of gonadotropin release from the pituitary). The mechanism for appetite stimulation in cachexia is not fully understood but is believed to involve hypothalamic effects, possibly through modulation of cytokine production (e.g., TNF-alpha, IL-1, IL-6) or neuropeptide Y pathways.
Pharmacokinetics
Absorption:
Bioavailability:
Variable, approximately 60-80% for conventional tablets; higher for micronized suspension.
Tmax:
1-5 hours (conventional tablets); 2-3 hours (micronized suspension).
FoodEffect:
Food increases the extent of absorption.
Distribution:
Vd:
Approximately 20 L/kg.
ProteinBinding:
Approximately 97% (primarily to albumin).
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 20-50 hours (mean 34 hours).
Clearance:
Not readily available, primarily renal excretion.
ExcretionRoute:
Urine (57-78%), feces (8-30%).
Unchanged:
Approximately 5-8% of the dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
For appetite stimulation, clinical effect may take several weeks (e.g., 2-4 weeks). For antineoplastic effects, onset is variable and depends on the specific cancer type.
PeakEffect:
For appetite stimulation, peak weight gain typically occurs after 10-12 weeks of therapy.
DurationOfAction:
Duration of effect persists as long as therapy is continued.
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek emergency medical attention:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of high blood sugar: confusion, drowsiness, excessive thirst or hunger, frequent urination, flushing, rapid breathing, or fruity-smelling breath.
Signs of Cushing's syndrome: weight gain in the upper back or abdomen, moon face, severe headache, or slow wound healing.
Signs of adrenal insufficiency: severe nausea or vomiting, extreme dizziness or fainting, muscle weakness, fatigue, mood changes, decreased appetite, or weight loss.
Signs of high blood pressure: severe headache or dizziness, fainting, or changes in vision.
Shortness of breath, sudden weight gain, or swelling in the arms or legs.
Abnormal vaginal bleeding.
Mood changes.
Decreased libido.
Erectile dysfunction.
Fever.
Pain or numbness in the hands or wrists.
Tumor flare reaction: increased pain or tenderness at the tumor site, hot flashes, or other symptoms. Notify your doctor immediately if you experience any of these symptoms.
Blood clots: although rare, blood clots can be life-threatening. Seek medical attention immediately if you experience chest, arm, back, neck, or jaw pain or pressure; coughing up blood; numbness or weakness on one side of the body; difficulty speaking or thinking; changes in balance or vision; shortness of breath; or swelling, warmth, or pain in the leg or arm.
Other Possible Side Effects
As with any medication, you may experience side effects. While many people do not experience significant side effects or only have mild ones, it is essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not resolve, contact your doctor:
Nausea or vomiting.
Headache.
Increased appetite.
Weight gain.
Insomnia.
Gas.
Fatigue or weakness.
Hair loss.
Hot flashes.
Excessive sweating.
* Diarrhea.
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek emergency medical attention:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of high blood sugar: confusion, drowsiness, excessive thirst or hunger, frequent urination, flushing, rapid breathing, or fruity-smelling breath.
Signs of Cushing's syndrome: weight gain in the upper back or abdomen, moon face, severe headache, or slow wound healing.
Signs of adrenal insufficiency: severe nausea or vomiting, extreme dizziness or fainting, muscle weakness, fatigue, mood changes, decreased appetite, or weight loss.
Signs of high blood pressure: severe headache or dizziness, fainting, or changes in vision.
Shortness of breath, sudden weight gain, or swelling in the arms or legs.
Abnormal vaginal bleeding.
Mood changes.
Decreased libido.
Erectile dysfunction.
Fever.
Pain or numbness in the hands or wrists.
Tumor flare reaction: increased pain or tenderness at the tumor site, hot flashes, or other symptoms. Notify your doctor immediately if you experience any of these symptoms.
Blood clots: although rare, blood clots can be life-threatening. Seek medical attention immediately if you experience chest, arm, back, neck, or jaw pain or pressure; coughing up blood; numbness or weakness on one side of the body; difficulty speaking or thinking; changes in balance or vision; shortness of breath; or swelling, warmth, or pain in the leg or arm.
Other Possible Side Effects
As with any medication, you may experience side effects. While many people do not experience significant side effects or only have mild ones, it is essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other symptoms that bother you or do not resolve, contact your doctor:
Nausea or vomiting.
Headache.
Increased appetite.
Weight gain.
Insomnia.
Gas.
Fatigue or weakness.
Hair loss.
Hot flashes.
Excessive sweating.
* Diarrhea.
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Sudden chest pain or shortness of breath (signs of a blood clot in the lung)
- Pain, swelling, or redness in your leg (signs of a blood clot in the leg)
- Unusual vaginal bleeding (for women)
- Increased thirst or urination, increased hunger, blurred vision, or unusual fatigue (signs of high blood sugar)
- Severe weakness, dizziness, nausea, vomiting, or loss of appetite (signs of adrenal problems, especially if stopping the medicine)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
If you have a known allergy to megestrol acetate or any component of this medication. Describe the allergic reaction and symptoms you experienced.
If you are taking dofetilide, as this may interact with the medication.
If you are pregnant or think you may be pregnant. Note that this medication should not be used to stimulate appetite during pregnancy.
If you are breastfeeding, as you should not breastfeed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health issues. Never start, stop, or adjust the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
If you have a known allergy to megestrol acetate or any component of this medication. Describe the allergic reaction and symptoms you experienced.
If you are taking dofetilide, as this may interact with the medication.
If you are pregnant or think you may be pregnant. Note that this medication should not be used to stimulate appetite during pregnancy.
If you are breastfeeding, as you should not breastfeed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health issues. Never start, stop, or adjust the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.
One of the potential side effects of this medication is high blood sugar, which may lead to the development of new-onset diabetes or worsen existing diabetes. It is crucial to check your blood sugar levels as instructed by your doctor.
This medication may also affect your body's natural production of steroids. If you experience a severe infection, undergo surgery, or suffer an injury, notify your doctor immediately. Additionally, if you experience severe dizziness, fainting, persistent nausea and vomiting, or extreme fatigue and weakness, seek medical attention right away, as you may require steroid replacement therapy. Consult with your doctor to discuss the best course of action.
If you are pregnant or planning to become pregnant, it is vital to be aware that this medication may harm the unborn baby. To confirm that you are not pregnant, your doctor may require a pregnancy test before initiating treatment. To prevent pregnancy while taking this medication, use a reliable form of birth control. If you become pregnant or suspect you may be pregnant while taking this medication, contact your doctor immediately.
One of the potential side effects of this medication is high blood sugar, which may lead to the development of new-onset diabetes or worsen existing diabetes. It is crucial to check your blood sugar levels as instructed by your doctor.
This medication may also affect your body's natural production of steroids. If you experience a severe infection, undergo surgery, or suffer an injury, notify your doctor immediately. Additionally, if you experience severe dizziness, fainting, persistent nausea and vomiting, or extreme fatigue and weakness, seek medical attention right away, as you may require steroid replacement therapy. Consult with your doctor to discuss the best course of action.
If you are pregnant or planning to become pregnant, it is vital to be aware that this medication may harm the unborn baby. To confirm that you are not pregnant, your doctor may require a pregnancy test before initiating treatment. To prevent pregnancy while taking this medication, use a reliable form of birth control. If you become pregnant or suspect you may be pregnant while taking this medication, contact your doctor immediately.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
- Shortness of breath
- Cough
- Tachycardia (rapid heart rate)
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is supportive.
Drug Interactions
Major Interactions
- Indinavir (megestrol acetate can significantly decrease indinavir plasma concentrations, potentially leading to loss of virologic response and development of resistance).
Moderate Interactions
- Warfarin (potential for altered INR, monitor coagulation parameters closely).
- Antidiabetic agents (megestrol acetate may cause hyperglycemia, requiring adjustment of antidiabetic medication dosage).
- Other hormonal agents (additive hormonal effects).
Monitoring
Baseline Monitoring
Weight and Nutritional Status
Rationale: To establish baseline for monitoring efficacy in cachexia/anorexia.
Timing: Prior to initiation of therapy.
Blood Glucose
Rationale: Megestrol acetate can cause hyperglycemia, especially in diabetic patients.
Timing: Prior to initiation, particularly in patients with diabetes or risk factors for diabetes.
Adrenal Function (e.g., cortisol levels)
Rationale: For patients on long-term therapy, to assess for potential adrenal suppression, especially if considering abrupt discontinuation.
Timing: Consider prior to initiation for long-term use, and before discontinuation after prolonged therapy.
Routine Monitoring
Weight and Nutritional Status
Frequency: Weekly to monthly
Target: Increase in weight or stabilization of weight loss.
Action Threshold: Lack of weight gain or continued significant weight loss may indicate treatment failure.
Blood Glucose
Frequency: Periodically, more frequently in diabetic patients.
Target: Within normal limits or individualized glycemic targets.
Action Threshold: Persistent hyperglycemia requiring adjustment of antidiabetic therapy or discontinuation of megestrol.
Signs/Symptoms of Thromboembolism
Frequency: Continuously
Target: Absence of symptoms.
Action Threshold: New onset of chest pain, shortness of breath, leg pain/swelling, or other signs of DVT/PE.
Symptom Monitoring
- Peripheral edema
- Signs of deep vein thrombosis (DVT) such as leg pain, swelling, redness, warmth
- Signs of pulmonary embolism (PE) such as sudden shortness of breath, chest pain, cough, rapid heart rate
- Symptoms of hyperglycemia (increased thirst, increased urination, fatigue, blurred vision)
- Symptoms of adrenal insufficiency (fatigue, weakness, nausea, vomiting, dizziness) if therapy is abruptly discontinued after prolonged use.
Special Patient Groups
Pregnancy
Contraindicated in pregnancy. Megestrol acetate can cause fetal harm when administered to a pregnant woman. It is a progestational agent and has been associated with adverse effects on fetal development.
Trimester-Specific Risks:
First Trimester:
High risk of fetal abnormalities, including hypospadias in male fetuses.
Second Trimester:
Risk of fetal abnormalities and potential for adverse effects on fetal development.
Third Trimester:
Risk of fetal abnormalities and potential for adverse effects on fetal development.
Lactation
Contraindicated during breastfeeding. Megestrol acetate is excreted in human milk and may cause serious adverse reactions in the nursing infant. A decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
High risk (L5) due to potential for adverse effects on infant development and hormonal disruption.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended.
Geriatric Use
Use with caution in elderly patients. Elderly patients may be at increased risk for adverse effects such as thromboembolic events, edema, and hyperglycemia. Dosage adjustments may be necessary based on renal function and overall health status.
Clinical Information
Clinical Pearls
- Megestrol acetate is not indicated for the prevention of weight loss in patients with cancer or other conditions, only for the treatment of existing anorexia/cachexia.
- Adrenal suppression can occur with long-term use; gradual tapering of the dose is recommended if discontinuing after prolonged therapy to prevent symptoms of adrenal insufficiency.
- Patients should be monitored for signs and symptoms of thromboembolic events (e.g., DVT, PE), especially those with a history of such events or other risk factors.
- Can cause hyperglycemia, particularly in diabetic patients; blood glucose monitoring is important.
- The 40mg tablet strength is commonly used for cancer indications, while higher doses (e.g., 400-800mg) are typically used for appetite stimulation/cachexia, often with the oral suspension formulation (Megace ES) due to better bioavailability and ease of administration at higher doses.
Alternative Therapies
- For appetite stimulation/cachexia: Dronabinol, Mirtazapine, Corticosteroids (short-term).
- For breast cancer: Tamoxifen, Aromatase inhibitors (e.g., Anastrozole, Letrozole, Exemestane), Fulvestrant, Chemotherapy, Targeted therapies.
- For endometrial cancer: Progestins (other), Chemotherapy, Radiation therapy.
Cost & Coverage
Average Cost:
$20 - $100 per 30 tablets (40mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it occurred.