HALOTESTIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HALOTESTIN (HALOTESTIN).
Fluoxymesterone is a synthetic androgen that binds to androgen receptors, activating gene transcription and promoting protein synthesis, leading to anabolic and androgenic effects.
| Metabolism | Hepatic via CYP3A4 |
| Excretion | Renal: 90% as glucuronide and sulfate conjugates; fecal: 10%. |
| Half-life | Terminal elimination half-life: 9.6 hours. Clinical context: Steady-state achieved after ~48 hours. |
| Protein binding | 98% bound to sex hormone-binding globulin (SHBG) and albumin. |
| Volume of Distribution | Vd: 0.5-0.8 L/kg, indicating distribution into total body water and some tissue binding. |
| Bioavailability | Oral: 10-20% due to extensive first-pass metabolism; IM: 100%. |
| Onset of Action | Oral: 1-2 hours for androgenic effects; IM: 24-48 hours. |
| Duration of Action | Oral: 6-8 hours for replacement therapy; IM: 2-4 weeks for depot effects. |
10-20 mg orally three to four times daily for replacement therapy; 2-10 mg orally daily for delayed puberty in males.
| Dosage form | TABLET |
| Renal impairment | GFR <30 mL/min: use with caution; reduce dose to 5-10 mg twice daily. GFR <10 mL/min: avoid use. |
| Liver impairment | Child-Pugh class A: no adjustment. Child-Pugh class B: reduce dose by 50%. Child-Pugh class C: contraindicated. |
| Pediatric use | For delayed puberty: 2.5-5 mg orally daily for up to 6 months; titrate based on response. Not recommended for prepubertal children. |
| Geriatric use | Start with lowest effective dose (2.5 mg orally daily) to minimize risk of prostatic hypertrophy and fluid retention. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HALOTESTIN (HALOTESTIN).
| Breastfeeding | Excreted into breast milk; M/P ratio unknown. Contraindicated during breastfeeding due to potential for androgenization of the infant and suppression of lactation. |
| Teratogenic Risk | Pregnancy Category X. Contraindicated in all trimesters due to virilization of female fetus (clitoral enlargement, labial fusion) and potential for skeletal abnormalities. Androgenic effects may occur at any gestational age. |
| Fetal Monitoring |
■ FDA Black Box Warning
Prolonged use of androgens has been associated with development of hepatocellular carcinoma and peliosis hepatis.
| Serious Effects |
Hypersensitivity to fluoxymesterone, known or suspected prostate cancer or male breast cancer, pregnancy, lactation, severe hepatic disease.
| Precautions | Monitor for signs of virilization in women, fluid retention, hypercalcemia, and hepatic dysfunction. May cause priapism in men. Use with caution in patients with cardiac, renal, or hepatic disease. |
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| Monitor maternal hepatic function, lipid profile, and signs of virilization (e.g., hirsutism, voice deepening). If inadvertent exposure occurs, fetal ultrasound to assess genital anatomy and growth. |
| Fertility Effects | May suppress gonadotropin secretion and cause oligospermia or azoospermia in males. In females, may disrupt menstrual cycle and reduce fertility. Effects are reversible upon discontinuation. |