METHYLTESTOSTERONE
Clinical safety rating: avoid
Corticosteroids may increase edema risk and anticoagulants may have increased effects Can cause polycythemia and increased risk of cardiovascular events.
Methyltestosterone is a synthetic androgen that binds to and activates androgen receptors (AR) in target tissues, promoting the development and maintenance of male secondary sexual characteristics and anabolic effects. It also suppresses gonadotropin-releasing hormone (GnRH) secretion via negative feedback, reducing endogenous testosterone production.
| Metabolism | Primarily hepatic via cytochrome P450 (CYP3A4) oxidation and conjugation (glucuronidation and sulfation). Metabolites include 17-keto steroids and other polar compounds. Excretion is primarily renal. |
| Excretion | Renal (primarily as glucuronide and sulfate conjugates, ~90%); fecal (~10%). Unchanged drug is minimal. |
| Half-life | 2-4 hours (terminal); requires multiple daily dosing or transdermal route due to short half-life. |
| Protein binding | 98% bound to albumin and sex hormone-binding globulin (SHBG). |
| Volume of Distribution | 0.5-0.8 L/kg; reflects extensive tissue distribution (e.g., muscle, prostate) and high protein binding. |
| Bioavailability | Oral: low (<20%) due to extensive first-pass hepatic metabolism; IM: 100%; Transdermal: ~10% (variation by site); Buccal: ~40-90% depending on formulation. |
| Onset of Action | IM injection: 10-15 minutes; Oral: 1-2 hours; Buccal: 30-60 minutes; Transdermal: 2-4 hours. |
| Duration of Action | IM: 2-4 weeks (depot); Oral: 2-4 hours; Buccal: 4-6 hours; Transdermal: 24 hours (patch). Note: Clinical effects (e.g., erythropoiesis, anabolism) persist beyond serum levels. |
| Molecular Weight | 288.42 |
10-50 mg orally once daily or divided twice daily, or 10-25 mg buccally twice daily.
| Dosage form | TABLET |
| Renal impairment | No specific guidelines; use caution in severe impairment (CrCl <30 mL/min) due to potential fluid retention and increased toxicity. |
| Liver impairment | Contraindicated in Child-Pugh class B or C; use reduced dose (e.g., 5-10 mg daily) with close monitoring in mild impairment (Child-Pugh A). |
| Pediatric use | Not recommended for growth promotion due to risk of premature epiphyseal closure; dosage for delayed puberty: 2.5-10 mg orally daily for 4-6 months. |
| Geriatric use | Initiate at lowest dose (e.g., 5-10 mg daily) due to increased risk of prostatic hypertrophy, fluid retention, and androgenic effects. |
| 1st trimester | Contraindicated due to masculinization of female fetus and potential teratogenic effects. |
| 2nd trimester | Contraindicated due to virilization of female fetus and adverse effects on fetal development. |
| 3rd trimester | Contraindicated due to risk of virilization and potential hepatic toxicity in the newborn. |
Clinical note
Corticosteroids may increase edema risk and anticoagulants may have increased effects Can cause polycythemia and increased risk of cardiovascular events.
| FDA category | Contraindicated |
| Placental transfer | Crosses the placenta; documented transfer with risk of fetal harm. |
| Breastfeeding |
■ FDA Black Box Warning
WARNING: Prolonged use of high doses of androgens has been associated with hepatic adenomas, hepatocellular carcinoma, and peliosis hepatis. Methyltestosterone is also associated with cholestatic hepatitis and jaundice. Women should be monitored for virilization. Androgens are not indicated for enhancement of athletic performance and may cause serious adverse effects.
| Common Effects | Acne |
| Serious Effects |
PregnancyBreastfeedingKnown or suspected carcinoma of the breast in femalesKnown or suspected carcinoma of the prostate in malesSevere hepatic impairmentNephrotic syndromeHypercalcemiaHypersensitivity to methyltestosterone
| Precautions | Hepatotoxicity: Monitor liver function tests; jaundice or hepatitis may occur., Cardiovascular risk: May increase LDL, decrease HDL, and elevate blood pressure; caution in patients with heart failure or coronary artery disease., Prostatic hypertrophy/carcinoma: Androgens may accelerate growth; contraindicated in known or suspected prostate cancer., Polycythemia: Monitor hematocrit/hemoglobin., Lipid profile: Monitor for dyslipidemia., Gynecomastia, priapism, and premature epiphyseal closure in adolescents., Fluid retention: Caution in patients with conditions aggravated by edema (e.g., renal, hepatic, cardiac impairment). |
Loading safety data…
| Excreted in breast milk; may cause virilization in female infants and other adverse effects. Breastfeeding is not recommended during therapy. |
| Lactation Rating | L5 - Contraindicated |
| Teratogenic Risk | First trimester: Irreversible masculinization of female fetus (clitoral hypertrophy, labial fusion). Second trimester: Continued virilization risk. Third trimester: Potential for clitoral enlargement. Contraindicated in pregnancy. |
| Fetal Monitoring | Monitor maternal liver function, lipid profile, hemoglobin/hematocrit (polycythemia), blood pressure. Fetal ultrasound if inadvertent exposure to assess for abnormalities. |
| Fertility Effects | Suppresses gonadotropin release, may inhibit spermatogenesis in males (reversible, decreased semen volume/clomiphene-responsive). Females: may cause menstrual irregularities, anovulation, and reduced fertility. |
| Food/Dietary | No specific food interactions; however, avoid excessive alcohol due to hepatotoxicity risk. Maintain a low-sodium diet if fluid retention occurs. |
| Clinical Pearls | Monitor liver function tests regularly due to risk of hepatotoxicity; avoid in men with prostate or breast cancer; watch for erythrocytosis (check hematocrit); use caution in patients with cardiovascular or renal disease due to fluid retention; potent androgen may cause virilization in women and premature epiphyseal closure in children. |
| Patient Advice | Take exactly as prescribed; do not increase dose without consulting your doctor. · Report signs of liver problems: yellowing skin/eyes, dark urine, abdominal pain. · Women: report hoarseness, acne, hirsutism, or menstrual irregularities immediately. · Men: report any breast enlargement, difficulty urinating, or persistent erections. · Avoid excessive alcohol consumption as it may increase liver damage risk. · Regular blood tests (liver function, cholesterol, hematocrit) are required. · May cause infertility; discuss family planning with your doctor if applicable. · Keep out of reach of children; this medication can cause serious harm. |