VANTAS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VANTAS (VANTAS).
Gonadotropin-releasing hormone (GnRH) agonist; continuous stimulation suppresses pituitary gonadotropin secretion, resulting in decreased testosterone production.
| Metabolism | Primarily metabolized by peptidases; not dependent on cytochrome P450 enzymes. |
| Excretion | Renal: negligible. Fecal: ~100% (unchanged drug). Histrelin is not metabolized and is excreted unchanged in feces via biliary elimination. |
| Half-life | Terminal elimination half-life approximately 4 weeks (28 days) due to continuous release from the implant; after implant removal, plasma concentrations decline with a half-life of about 3-4 days. |
| Protein binding | Approximately 50-70% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 4-5 L/kg, indicating extensive distribution into tissues. |
| Bioavailability | Subcutaneous implant: 100% (systemic delivery via continuous release). |
| Onset of Action | Subcutaneous implant: Suppression of testosterone to castrate levels occurs within 2-4 weeks after implantation. |
| Duration of Action | The implant provides continuous therapeutic effect for 12 months; after removal, testosterone levels return to baseline within 4-8 weeks. |
10 mg subcutaneously every 24 weeks.
| Dosage form | IMPLANT |
| Renal impairment | No adjustment required for creatinine clearance ≥15 mL/min. Insufficient data for GFR <15 mL/min. |
| Liver impairment | No adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C). |
| Pediatric use | Not approved for use in pediatric patients. |
| Geriatric use | No specific dose adjustment required; monitor for cardiovascular effects and bone mineral density loss. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VANTAS (VANTAS).
| Breastfeeding | Not recommended. Excretion into human milk unknown; M/P ratio not determined. Theoretical risk of adverse effects in nursing infant due to hormonal activity. |
| Teratogenic Risk | Category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: Risk of spontaneous abortion and major congenital malformations including urogenital abnormalities. Second and third trimesters: Risk of fetal androgenization, specifically clitoral hypertrophy and labial fusion in female fetuses. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to histrelin or any component of the formulation.","Pregnancy (potential fetal harm)."]
| Precautions | ["Transient increase in serum testosterone during initial treatment may cause worsening of prostate cancer symptoms or ureteral obstruction.","Monitor serum testosterone levels periodically.","May cause injection site reactions including pain, bruising, and nodule formation.","Not indicated for use in women or children."] |
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| Pregnancy test required prior to initiation and monthly during therapy. Monitor for signs of pregnancy. In case of accidental exposure, immediate discontinuation and fetal ultrasound for genital development. |
| Fertility Effects | Impairs fertility in males and females via suppression of gonadotropins. Males: Oligospermia or azoospermia, testicular atrophy, decreased libido. Females: Anovulation, menstrual irregularities, reversible upon discontinuation. |