Navigation

Megace

Megace - General Information

17-Hydroxy-6-methylpregna-3,6-diene-3,20-dione. A progestational hormone used most commonly as the acetate ester. As the acetate, it is more potent than progesterone both as a progestagen and as an ovulation inhibitor. It has also been used in the palliative treatment of breast cancer. [PubChem]

 

Pharmacology of Megace

Megace is a synthetic progestin and has the same physiologic effects as natural progesterone. The precise mechanism of megestrol’s antianorexic and anticachetic effects is unknown. Initially developed as a contraceptive, it was first evaluated in breast cancer treatment in 1967.

 

Megace for patients

Patients using Megace® ES (megestrol acetate) should receive the following instructions:

1. This medication is to be used as directed by the physician.
2. Megace® ES (625 mg/5 mL) does not contain the same amount of megestrol acetate as Megace® oral suspension or any of the other megestrol acetate oral suspensions. Megace® ES contains 625 mg of megestrol acetate per 5 mL whereas Megace® oral suspension and other megestrol acetate oral suspensions contain 800 mg per 20 mL.
3. The prescriber should inform the patient about the product differences to avoid overdosing or underdosing of megestrol acetate. The recommended adult dosage of Megace® ES is one teaspoon (5 mL) once a day. Please see table in DOSAGE AND ADMINISTRATION section.
4. Report any adverse reaction experiences while taking this medication.
5. Use contraception while taking this medication if you are a woman capable of becoming pregnant.
6. Notify your physician if you become pregnant while taking this medication.

 

Megace Interactions

Pharmacokinetic studies show that there are no significant alterations in pharmacokinetic parameters of zidovudine or rifabutin to warrant dosage adjustment when megestrol acetate is administered with these drugs. A pharmacokinetic study demonstrated that coadministration of megestrol acetate and indinavir results in a significant decrease in the pharmacokinetic parameters (~36% for Cmax and ~28% for AUC) of indinavir. Administration of a higher dose of indinavir should be considered when coadministering with megestrol acetate. The effects of indinavir, zidovudine or rifabutin on the pharmacokinetics of megestrol acetate were not studied.

 

Megace Contraindications

History of hypersensitivity to megestrol acetate or any component of the formulation. Known or suspected pregnancy.

 

Additional information about Megace

Megace Indication: For the treatment of anorexia, cachexia, or an unexplained, significant weight loss in patients with a diagnosis of acquired immunodeficiency syndrome (AIDS). Also used to treat breast cancer, endometrial cancer, and prostate cancer in Canada and some other countries.
Mechanism Of Action: Several investigators have reported on the appetite enhancing property of megestrol acetate and its possible use in cachexia. The precise mechanism by which megestrol acetate produces effects in anorexia and cachexia is unknown at the present time. The biochemical mechanism of progestin antitumour activity is not well but may involve interaction with progesterone and glucocorticoid receptors, androgenic properties. Megace also has direct cytotoxic effects on breast cancer cells in tissue culture and suppresses luteinising hormone release from the pituitary.
Drug Interactions: Amobarbital The enzyme inducer decreases the effect of hormones
Aprobarbital The enzyme inducer decreases the effect of hormones
Butabarbital The enzyme inducer decreases the effect of hormones
Butalbital The enzyme inducer decreases the effect of hormones
Butethal The enzyme inducer decreases the effect of hormones
Heptabarbital The enzyme inducer decreases the effect of hormones
Hexobarbital The enzyme inducer decreases the effect of hormones
Griseofulvin The enzyme inducer decreases the effect of hormones
Ethotoin The enzyme inducer decreases the effect of hormones
Fosphenytoin The enzyme inducer decreases the effect of hormones
Phenytoin The enzyme inducer decreases the effect of hormones
Mephenytoin The enzyme inducer decreases the effect of hormones
Talbutal The enzyme inducer decreases the effect of hormones
Secobarbital The enzyme inducer decreases the effect of hormones
Primidone The enzyme inducer decreases the effect of hormones
Pentobarbital The enzyme inducer decreases the effect of hormones
Phenobarbital The enzyme inducer decreases the effect of hormones
Methohexital The enzyme inducer decreases the effect of hormones
Methylphenobarbital The enzyme inducer decreases the effect of hormones
Food Interactions: Take with food.
Generic Name: Megestrol
Synonyms: Megestrol Acetate; Megestrolo [DCIT]; Megestrolum [INN-Latin]; Megestryl acetate; MGA
Drug Category: Antineoplastic Agents, Hormonal; Contraceptives, Oral, Synthetic
Drug Type: Small Molecule; Approved

Other Brand Names containing Megestrol: Magestin; Maygace; Megace; Megeron; Megestat; Megestil; Megestin; Nia; Niagestin; Ovaban; Ovarid; Volidan;
Absorption: Variable, but well absorbed orally.
Toxicity (Overdose): No serious unexpected side effects have resulted from studies involving megestrol acetate oral suspension administered in dosages as high as 1200 mg/day.
Protein Binding: Not Available
Biotransformation: Primarily hepatic. Megestrol metabolites which were identified in urine constituted 5% to 8% of the dose administered. Respiratory excretion as labeled carbon dioxide and fat storage may have accounted for at least part of the radioactivity not found in urine and feces. No active metabolites have been identified.
Half Life: 34 hours
Dosage Forms of Megace: Tablet Oral
Suspension Oral
Chemical IUPAC Name: (8R,9S,10R,13S,14S,17R)-17-acetyl-17-hydroxy-6,10,13-trimethyl-2,8,9,11,12,14,15,16-octahydro-1H-cyclopenta[a]phenanthren-3-one
Chemical Formula: C22H30O3
Megestrol on Wikipedia: https://en.wikipedia.org/wiki/Megestrol
Organisms Affected: Humans and other mammals