DELATESTRYL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DELATESTRYL (DELATESTRYL).
Testosterone ester; binds to androgen receptors, activating gene transcription and promoting protein synthesis, muscle growth, and secondary sexual characteristics.
| Metabolism | Primarily hepatic via CYP3A4 and other cytochrome P450 enzymes; undergoes ester hydrolysis to testosterone, then further metabolized to androstenedione, dihydrotestosterone, and glucuronide conjugates. |
| Excretion | Urinary (90% as glucuronide and sulfate conjugates, 5% as unchanged drug); fecal (5%) |
| Half-life | 8 days (terminal); requires 5-6 weeks to reach steady state with weekly dosing |
| Protein binding | 97-99% bound to sex hormone-binding globulin (SHBG) and albumin |
| Volume of Distribution | 0.5-0.8 L/kg; large distribution into muscle and adipose tissue, with slow release from injection site |
| Bioavailability | Intramuscular: 100% (complete absorption from oily depot); oral: <5% due to extensive first-pass metabolism |
| Onset of Action | Intramuscular: 24-48 hours for clinical effect; peak plasma levels at 24-72 hours |
| Duration of Action | Intramuscular: 2-4 weeks (clinical duration); residual effects may persist up to 6 weeks after discontinuation |
| Molecular Weight | 400.6 Da (testosterone enanthate) |
50 to 200 mg intramuscularly every 2 to 4 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required; not significantly renally eliminated. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C); use with caution in mild to moderate impairment. |
| Pediatric use | 50 mg intramuscularly every 4 weeks for delayed puberty; adjust based on response. |
| Geriatric use | Use lowest effective dose; monitor for prostate enlargement, fluid retention, and cardiovascular effects. |
| 1st trimester | Contraindicated: Testosterone derivatives can cause virilization of female fetus; risk of clitoromegaly, labial fusion. |
| 2nd trimester | Contraindicated: Continued risk of virilization; androgenic effects on fetal development. |
| 3rd trimester | Contraindicated: Potential for premature closure of epiphyses, virilization, and other adverse effects. |
Clinical note
Comprehensive clinical and safety monograph for DELATESTRYL (DELATESTRYL).
| Placental transfer | Measurable; androgens cross the placenta and can cause virilization of female fetus. |
| Breastfeeding | Testosterone enanthate is excreted into breast milk in small amounts; potential for adverse effects in the infant including virilization and growth acceleration. Use is not recommended; consider alternative therapy. |
■ FDA Black Box Warning
Virilization has been reported in children; use with caution in patients with conditions susceptible to edema; prolonged use may cause azoospermia.
| Serious Effects |
Known hypersensitivity to testosterone or any componentPregnancyBreastfeedingProstate cancerMale breast cancerSevere hepatic impairment
| Precautions | Monitor for polycythemia, sleep apnea, and prostatic hyperplasia; may increase risk of cardiovascular events; use with caution in patients with renal, hepatic, or cardiac disease. |
| Food/Dietary | No specific food interactions. Avoid excessive alcohol consumption as it may affect liver function and hormone levels. |
Loading safety data…
| Lactation Rating |
| L4 - Possibly Hazardous (or 'Avoid') |
| Teratogenic Risk | FDA Pregnancy Category X. Contraindicated in pregnancy. Androgens can cause virilization of female fetus (clitoromegaly, labial fusion, urogenital sinus abnormality) when administered during the first trimester; during second and third trimesters, can cause ambiguous genitalia in female fetuses and precocious sexual development in male fetuses. |
| Fetal Monitoring | Monitor maternal signs of virilization (hirsutism, acne, voice deepening); fetal ultrasound for sexual development if inadvertent exposure; maternal liver function tests, lipid profile, and hematocrit due to increased erythropoiesis risk. |
| Fertility Effects | Can impair spermatogenesis in males (oligospermia, decreased sperm motility) and may cause ovulation suppression or menstrual irregularities in females. Reversible upon discontinuation. |
| Clinical Pearls |
| Testosterone enanthate (Delatestryl) is a long-acting injectable testosterone ester. Monitor hematocrit and lipids; avoid in men with prostate or breast cancer. Use with caution in sleep apnea and severe heart failure. Avoid in women who are or may become pregnant. |
| Patient Advice | This medication is given as an injection into a muscle, usually every 1 to 4 weeks. · Report any signs of allergic reaction, difficulty breathing, or swelling of the face, lips, or throat. · Tell your doctor if you have new or worsening chest pain, shortness of breath, or swelling in your ankles/feet. · Do not take this medication if you are pregnant or planning to become pregnant. · Regular blood tests are needed to monitor testosterone levels, blood count, and prostate health (in men). · Possible side effects include acne, increased body hair, mood changes, and changes in sex drive. · Keep all appointments for injections and lab work. |