TRELSTAR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRELSTAR (TRELSTAR).
Gonadotropin-releasing hormone (GnRH) agonist. Chronic administration suppresses pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion, leading to reduced testicular and ovarian steroidogenesis.
| Metabolism | Metabolized primarily via peptide hydrolysis; not a substrate for cytochrome P450 enzymes. |
| Excretion | Primarily hepatic metabolism; <5% excreted unchanged in urine; fecal elimination of metabolites accounts for approximately 20-30%. |
| Half-life | Terminal elimination half-life approximately 3 weeks (21-28 days) after intramuscular injection; sustained release formulation results in prolonged exposure. |
| Protein binding | Approximately 70-80% bound to plasma proteins, mainly albumin. |
| Volume of Distribution | Approximately 30-50 L/kg; large Vd indicates extensive tissue distribution and binding to tissues. |
| Bioavailability | Intramuscular: Approximately 100% for the injected dose due to slow release from the depot formulation; not administered orally due to peptide degradation. |
| Onset of Action | Intramuscular: Serum testosterone suppression to castrate levels occurs within 2-4 weeks after the first injection. |
| Duration of Action | Intramuscular: Single injection provides therapeutic serum levels for approximately 4 weeks; clinical effect (testosterone suppression) lasts for the dosing interval (monthly). |
| Molecular Weight | 1311.45 |
3.75 mg intramuscularly once every 4 weeks or 11.25 mg intramuscularly once every 12 weeks or 22.5 mg intramuscularly once every 24 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min; insufficient data for GFR <30 mL/min, use with caution. |
| Liver impairment | No dose adjustment required for Child-Pugh A or B; insufficient data for Child-Pugh C. |
| Pediatric use | Not indicated for pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment recommended; consider renal function due to age-related decline. |
| 1st trimester | TRELSTAR (triptorelin) is contraindicated in pregnancy. Based on its mechanism of action and animal studies, there is a risk of fetal harm, including spontaneous abortion and fetal malformations. It should not be used during the first trimester. |
| 2nd trimester | Same as t1. Use is contraindicated due to risk of fetal harm from hormonal disruption. |
| 3rd trimester | Same as t1. Use is contraindicated. |
Clinical note
Comprehensive clinical and safety monograph for TRELSTAR (TRELSTAR).
| Placental transfer | GnRH agonists are expected to cross the placenta. Animal studies have shown triptorelin crosses the placental barrier and can cause fetal effects. In humans, specific data are limited, but based on molecular weight and lipophilicity, placental transfer is likely. |
| Breastfeeding | It is unknown whether triptorelin is excreted in human milk. However, many GnRH agonists are excreted in breast milk and could potentially cause adverse effects in nursing infants. Due to the lack of data and potential for serious adverse reactions, breastfeeding is not recommended during TRELSTAR therapy. Consider alternative therapy or discontinue breastfeeding. |
■ FDA Black Box Warning
TRELSTAR is not indicated for use in women or pediatric patients except for central precocious puberty. Transient increase in testosterone during the first weeks of therapy may cause worsening of symptoms, including bone pain, spinal cord compression, or urinary tract obstruction.
| Serious Effects |
PregnancyHypersensitivity to triptorelin or any component of the formulation
| Precautions | Tumor flare: transient increase in testosterone may exacerbate signs/symptoms of prostate cancer (bone pain, spinal cord compression, hematuria, urethral obstruction)., Hyperglycemia and increased risk of diabetes mellitus; monitor blood glucose., Cardiovascular disease: increased risk of myocardial infarction, sudden cardiac death, stroke., QT/QTc interval prolongation: use with caution in patients with risk factors for QT prolongation (e.g., electrolyte abnormalities, concomitant QT-prolonging drugs)., Hypersensitivity reactions: angioedema, anaphylaxis; discontinue if severe allergic reaction occurs., Seizures and convulsions have been reported with GnRH agonists., Effect on bone density: long-term use may cause bone loss; monitor bone health. |
| Food/Dietary |
Loading safety data…
| Lactation Rating | L5 (Avoid) |
| Teratogenic Risk | GnRH agonists like TRELSTAR (triptorelin) are contraindicated in pregnancy due to risk of fetal harm. Based on animal studies and mechanism of action, there is a potential increase in first-trimester pregnancy loss and fetal malformations if exposure occurs. Use is not recommended in pregnant women. If exposure occurs during pregnancy, advise the patient of the potential risk. |
| Fetal Monitoring | If inadvertent use during pregnancy, perform ultrasound to assess fetal development. For women of childbearing potential, perform pregnancy test before starting therapy and monthly during treatment. Monitor for signs of estrogen suppression (e.g., hot flashes, mood changes). |
| Fertility Effects | Triptorelin suppresses gonadotropin secretion, inhibiting ovulation and spermatogenesis, leading to reversible infertility during therapy. Duration of effect may persist for several weeks after discontinuation. Long-term use may delay return to fertility but is generally reversible. |
| No known food interactions. Grapefruit juice does not affect triptorelin. Maintain normal diet. |
| Clinical Pearls | TRELSTAR (triptorelin pamoate) is a GnRH agonist used for advanced prostate cancer. Initiate with a 1-week course of an antiandrogen (e.g., bicalutamide) to prevent flare phenomenon. Monitor serum testosterone levels; castrate level (<50 ng/dL) should be achieved within 2-4 weeks. Do not use in patients with prior hypersensitivity to GnRH agonists or analogs. Administer as a single intramuscular injection in the buttock; do not substitute dose for dose with other triptorelin formulations. Discontinue if spinal cord compression or ureteral obstruction develops. |
| Patient Advice | This medication is given as an injection by a healthcare provider every 1, 3, or 6 months depending on the formulation. · You may experience a temporary increase in bone pain, urinary symptoms, or tumor-related symptoms during the first few weeks of treatment (flare reaction). · Report new or worsening back pain, difficulty urinating, or leg weakness immediately as these may indicate spinal cord compression. · Hot flashes and sweating are common side effects; these are not harmful. · Long-term use may cause bone thinning; ensure adequate calcium and vitamin D intake. · This drug can cause birth defects; do not handle crushed tablets if you are pregnant or could become pregnant. · Your doctor will monitor blood tests including prostate-specific antigen (PSA) and testosterone levels regularly. |