Transient Increase in Serum Testosterone
VANTAS causes a transient increase in serum concentrations of testosterone during the first week of treatment. Patients may experience worsening of symptoms or onset of new symptoms, including bone pain, neuropathy, hematuria, or ureteral or bladder outlet obstruction.
Spinal Cord Compression and Urinary Tract Obstruction
Cases of spinal cord compression, which may result in paralysis, and ureteral obstruction, which may cause renal impairment, have been reported with GnRH agonists. Patients with metastatic vertebral lesions and/or with urinary tract obstruction should be closely observed during the first few weeks of therapy.
Difficulty Locating or Removing Implant
In all clinical trials combined, an implant was not recovered in 8 patients. For two of these [see Clinical Studies], serum testosterone rose above castrate level and the implant was neither palpable nor visualized with ultrasound. These two implants were believed to have been extruded without appreciation by the patients. In the other six, serum testosterone remained below the castrate level, but the implant was not palpable. No further diagnostic tests were conducted. One of these patients underwent in-clinic surgical exploration that did not locate the implant.
Implant insertion is a surgical procedure. Careful adherence to the recommended Insertion and Removal Procedures [see DOSAGE AND ADMINISTRATION] is advised to minimize the potential for complications and for implant expulsion. In addition, patients should be instructed to refrain from wetting the arm for 24 hours and from heavy lifting or strenuous exertion of the inserted arm for 7 days after implant insertion.
Hyperglycemia and Diabetes
Hyperglycemia and an increased risk of developing diabetes have been reported in men receiving GnRH agonists. Hyperglycemia may represent development of diabetes mellitus or worsening of glycemic control in patients with diabetes. Monitor blood glucose and/or glycosylated hemoglobin (HbA1c) periodically in patients receiving a GnRH agonist and manage with current practice for treatment of hyperglycemia or diabetes.
Increased risk of developing myocardial infarction, sudden cardiac death and stroke has been reported in association with use of GnRH agonists in men. The risk appears low based on the reported odds ratios, and should be evaluated carefully along with cardiovascular risk factors when determining a treatment for patients with prostate cancer. Patients receiving a GnRH agonist should be monitored for symptoms and signs suggestive of development of cardiovascular disease and be managed according to current clinical practice.
Response to VANTAS should be monitored by measuring serum concentrations of testosterone and prostate-specific antigen periodically, especially if the anticipated clinical or biochemical response to treatment has not been achieved.
Results of testosterone determinations are dependent on assay methodology. It is advisable to be aware of the type and precision of the assay methodology to make appropriate clinical and therapeutic decisions.
Patient Counseling Information
“See FDA-approved patient labeling (PATIENT INFORMATION)”
An information leaflet for patients is included with the product and should be given to the patient.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenicity studies were conducted in rats for 2 years at doses of 5, 25 or 150 mcg/kg/day (up to 22 times human exposures using body surface area comparisons, based on a 65 mcg/day dose in adults) and in mice for 18 months at doses of 20, 200, or 2000 mcg/kg/day (up to 150 times human exposure using body surface area comparisons, based on a 65 mcg/day dose in adults). As seen with other GnRH agonists, histrelin acetate injection administration was associated with an increase in tumors of hormonally responsive tissues. There was a significant increase in pituitary adenomas in rats. There was an increase in pancreatic islet-cell adenomas in treated female rats and a non-dose-related increase in testicular Leydig-cell tumors (highest incidence in the low-dose group). In mice, there was significant increase in mammary-gland adenocarcinomas in all treated females. In addition, there were increases in stomach papillomas in male rats given high doses, and an increase in histiocytic sarcomas in female mice at the highest dose.
Mutagenicity studies have not been performed with histrelin acetate. Saline extracts of implants with and without histrelin were negative in a battery of genotoxicity studies. Studies examining fertility following withdrawal of histrelin acetate have been conducted in rats and monkeys given subcutaneous daily doses of histrelin acetate for 6 months, at doses of up to 180 mcg /kg/day (up to 27-times [rat] and 54-times [monkey] adult clinical exposures using body surface area comparisons, based on a 65 mcg/day dose in humans). Full reversibility of fertility suppression was demonstrated. The development and reproductive performance of offspring from parents treated with histrelin acetate has not been investigated.
Use In Specific Populations
Pregnancy Category X [see CONTRAINDICATIONS].
VANTAS is contraindicated in females who are or may become pregnant. VANTAS can cause fetal harm when administered to a pregnant woman. The possibility exists that spontaneous abortion may occur. Major fetal abnormalities were observed in rabbits but not in rats after administration of histrelin acetate throughout gestation. There were increased fetal mortality and decreased fetal weights in rats and rabbits. The effects on fetal mortality are expected consequences of the alterations in hormonal levels brought about by this drug. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.
VANTAS is not indicated for use in women. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from VANTAS, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
VANTAS is not indicated for use in pediatric patients.
Last reviewed on RxList: 4/22/2013
This monograph has been modified to include the generic and brand name in many instances.
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