FORTESTA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FORTESTA (FORTESTA).
Testosterone replacement therapy; testosterone binds to and activates androgen receptors, influencing gene transcription and protein synthesis, leading to the development of male secondary sex characteristics and maintenance of libido, muscle mass, and bone density.
| Metabolism | Metabolized primarily in the liver via reduction and conjugation; major metabolites include androsterone and etiocholanolone; also undergoes some extrahepatic metabolism in skin. |
| Excretion | Primarily renal (90% as glucuronide and sulfate conjugates, 10% unchanged); approximately 1% fecal. |
| Half-life | Terminal elimination half-life is 3–4 hours; not clinically significant for once-daily transdermal administration due to sustained absorption. |
| Protein binding | Testosterone is 97–99% bound to sex hormone-binding globulin (SHBG) and albumin. |
| Volume of Distribution | Approximately 0.5–1.0 L/kg, indicating distribution into total body water and extensive tissue binding. |
| Bioavailability | Transdermal: Approximately 10% of applied dose reaches systemic circulation; exact absorption varies with application site and skin condition. |
| Onset of Action | Transdermal: Clinical effects (testosterone normalization) observed within 24 hours of first application. |
| Duration of Action | Transdermal: Approximately 24 hours with once-daily application; maintains steady-state testosterone levels within normal range. |
| Molecular Weight | 288.42 |
| Action Class | Antiprotozoal agents |
| Brand Substitutes | Neomex 500mg Tablet, Mebendex 500mg Tablet, Mebex 500mg Tablet |
Apply one 30 mg metered-dose transdermal system to abdomen or upper arm once daily at the same time each day.
| Dosage form | GEL, METERED |
| Renal impairment | No specific dose adjustment recommended; use with caution in severe renal impairment (CrCl <30 mL/min). |
| Liver impairment | No specific dose adjustment recommended for Child-Pugh A or B; avoid in Child-Pugh C due to lack of data. |
| Pediatric use | Not approved for use in pediatric patients. |
| Geriatric use | Limited data in patients >75 years; use lowest effective dose and monitor for adverse effects. |
| 1st trimester | FORTESTA (testosterone) is contraindicated in pregnancy. Androgens can cause virilization of the female fetus if administered during the first trimester when genital differentiation occurs. |
| 2nd trimester | Contraindicated. Continued exposure to androgens may lead to further virilization and potential adverse effects on fetal development. |
| 3rd trimester | Contraindicated. Androgens may cause adverse effects such as ambiguous genitalia in female fetuses and potential metabolic disturbances. |
Clinical note
Comprehensive clinical and safety monograph for FORTESTA (FORTESTA).
| Placental transfer | Testosterone is known to cross the placenta. Transfer is likely to occur, with potential for fetal androgenic effects, particularly in female fetuses. |
| Breastfeeding | Testosterone is excreted in breast milk and may cause virilization or unwanted androgenic effects in the nursing infant. Use during breastfeeding is not recommended. If unavoidable, the benefits should outweigh the risks. |
■ FDA Black Box Warning
WARNING: SECONDARY EXPOSURE TO TESTOSTERONE - Cases of secondary exposure to testosterone in children and women have been reported, including cases of virilization. Advise patients to strictly adhere to recommended use and apply to clean, dry skin; wash hands after application; cover application site with clothing; and wash site prior to skin-to-skin contact with others.
| Serious Effects |
PregnancyKnown or suspected prostate cancerKnown or suspected breast cancer in malesHypersensitivity to testosterone or any componentSevere urinary tract obstruction
| Precautions | Secondary exposure to testosterone (children and women), Worsening of benign prostatic hyperplasia (BPH), Increased risk of prostate cancer, Cardiovascular risk (including myocardial infarction and stroke) in patients with pre-existing risk factors, Hepatic effects: cholestatic jaundice, liver tumors, Edema with or without congestive heart failure, Polycythemia (increased hematocrit), Sleep apnea in susceptible individuals, Gynecomastia, Hypercalcemia in immobilized patients or those with metastatic breast cancer |
| Food/Dietary |
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| Lactation Rating | L5 - Contraindicated |
| Teratogenic Risk | FORTESTA (testosterone) is contraindicated in pregnancy due to masculinization of female fetus. Second and third trimester exposure may cause clitoromegaly, labial fusion, and other virilization. First trimester risk is theoretical but avoided. |
| Fetal Monitoring | Monitor maternal liver function, lipid profile, hemoglobin/hematocrit (polycythemia risk). Fetal monitoring via ultrasound for growth and anatomy if inadvertent exposure. Assess infant for virilization post-delivery. |
| Fertility Effects | Exogenous testosterone suppresses endogenous gonadotropins (LH, FSH), causing anovulation and infertility. Reversible upon discontinuation. May impair spermatogenesis in male partners. |
| No known food interactions. Take with or without food. |
| Clinical Pearls | FORTESTA (testosterone gel) is indicated for testosterone replacement therapy in adult males with hypogonadism. Apply to clean, dry, intact skin of the shoulders, upper arms, or abdomen. Avoid application to genital area. Wash hands thoroughly after application. Monitor serum testosterone levels 2-4 hours after application. Avoid skin-to-skin contact with others until gel has dried. Contraindicated in men with breast cancer or known/suspected prostate cancer. |
| Patient Advice | Apply the gel once daily, preferably in the morning. · Do not apply to scrotum, penis, or broken skin. · Wash hands immediately after application. · Allow gel to dry completely before dressing. · Avoid showering or swimming for at least 2 hours after application. · Keep children and women away from application site to prevent transmission. · Notify your doctor if you experience nipple pain, swelling, or difficulty urinating. · Serum testosterone levels and prostate-specific antigen (PSA) will be monitored regularly. |