VIADUR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VIADUR (VIADUR).
Leuprolide is a gonadotropin-releasing hormone (GnRH) agonist that stimulates pituitary gonadotropin release initially, followed by sustained suppression of pituitary gonadotropins due to receptor desensitization, leading to reduced testosterone production.
| Metabolism | Metabolized by peptidases in the liver and kidneys; major metabolite is a pentapeptide (M-1). |
| Excretion | Leuprolide acetate is primarily eliminated via hepatic metabolism and renal excretion. Approximately 48% of the dose is recovered in urine over 24 hours, with 5% as unchanged drug. Fecal excretion accounts for about 5%. |
| Half-life | The terminal elimination half-life of leuprolide acetate following subcutaneous administration is approximately 3 hours. In patients with renal impairment, half-life may be prolonged; however, no dose adjustment is recommended for mild-to-moderate impairment. |
| Protein binding | Approximately 43% of leuprolide acetate is bound to plasma proteins, primarily albumin. |
| Volume of Distribution | The volume of distribution for leuprolide acetate is approximately 27 L (0.39 L/kg for a 70 kg adult), indicating distribution into total body water and some tissue binding. |
| Bioavailability | Following subcutaneous administration of Viadur, the bioavailability of leuprolide acetate is approximately 94% relative to an immediate-release subcutaneous injection. |
| Onset of Action | Following subcutaneous injection of Viadur, serum leuprolide concentrations peak within 4 hours. Clinical suppression of testosterone to castrate levels is achieved within 2-4 weeks of initial dose. |
| Duration of Action | Viadur provides continuous release of leuprolide for 12 months. Testosterone suppression is maintained throughout the dosing interval. After discontinuation, testosterone levels return to baseline within 4-12 weeks. |
Leuprolide acetate implant 65 mg implanted subcutaneously in the inner aspect of the upper arm once yearly.
| Dosage form | IMPLANT |
| Renal impairment | No dose adjustment required for renal impairment; leuprolide pharmacokinetics are not significantly affected by renal function. |
| Liver impairment | No dose adjustment required for Child-Pugh Class A or B; use with caution in Class C due to limited data but no established adjustment. |
| Pediatric use | Not approved for use in pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment recommended; monitor for known adverse effects (e.g., hot flashes, bone density loss) in elderly patients. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VIADUR (VIADUR).
| Breastfeeding | It is not known whether leuprolide acetate is excreted in human breast milk. Due to the potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during treatment with Viadur. No M/P ratio is available. |
| Teratogenic Risk | FDA Pregnancy Category X. Viadur (leuprolide acetate implant) is contraindicated in pregnant women. Exposure during the first trimester is associated with an increased risk of fetal loss, spontaneous abortion, and congenital anomalies including cardiovascular and skeletal defects. There is no indication for use in pregnancy, and the drug should be discontinued immediately if pregnancy occurs. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to leuprolide or GnRH agonists","Pregnancy (contraindicated due to risk of fetal harm)"]
| Precautions | ["Tumor flare: transient worsening of symptoms (e.g., bone pain, spinal cord compression) may occur initially.","Hyperglycemia and increased risk of diabetes.","Cardiovascular risks (myocardial infarction, sudden cardiac death) with androgen deprivation therapy.","QT interval prolongation.","Seizures reported post-marketing.","Pituitary apoplexy (rare)."] |
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| Fetal Monitoring | Monitor pregnancy status with a serum pregnancy test before initiating therapy and monthly during treatment. If pregnancy is suspected, perform immediate pregnancy test and discontinue Viadur. No routine fetal monitoring is indicated as the drug is contraindicated. |
| Fertility Effects | Viadur causes reversible suppression of pituitary gonadotropins, leading to decreased estrogen and testosterone levels. In women, this results in amenorrhea and anovulation, effectively preventing conception during treatment. Fertility typically returns upon discontinuation. In men, spermatogenesis is suppressed but usually recovers after cessation. |