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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
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 |
| Breastfeeding | Excreted into breast milk. M/P ratio unknown. May cause virilization in female infants. Contraindicated during breastfeeding. |
| 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. |
■ 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 |
["Known or suspected carcinoma of the prostate or male breast","Known or suspected carcinoma of the breast in women (except palliative therapy for metastatic breast cancer)","Pregnancy (androgen exposure can cause fetal harm)","Lactation","Severe hepatic dysfunction or disease","Hypercalcemia: Androgens may increase calcium levels"]
| 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…
| 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. |