The diagnosis of central precocious puberty (CPP) must be established before treatment is initiated. Regular monitoring of CPP patients is needed to assess both patient response as well as compliance. This is particularly important during the first 6 to 8 weeks of treatment to assure that suppression of pituitary-gonadal function is rapid. Testing may include LH response to GnRH stimulation and circulating gonadal sex steroid levels. Assessment of growth velocity and bone age velocity should begin within 3 to 6 months of treatment initiation.

Some patients may not show suppression of the pituitary-gonadal axis by clinical and/or biochemical parameters. This may be due to lack of compliance with the recommended treatment regimen and may be rectified by recommending that the dosing be done by caregivers. If compliance problems are excluded, the possibility of gonadotropin independent sexual precocity should be reconsidered and appropriate examinations should be conducted. If compliance problems are excluded and if gonadotropin independent sexual precocity is not present, the dose of SYNAREL may be increased to 1800 mg/day administered as 600 mg tid.

As with other drugs that stimulate the release of gonadotropins or that induce ovulation, in adult women with endometriosis ovarian cysts have been reported to occur in the first two months of therapy with SYNAREL. Many, but not all, of these events occurred in women with polycystic ovarian disease. These cystic enlargements may resolve spontaneously, generally by about four to six weeks of therapy, but in some cases may require discontinuation of drug and/or surgical intervention. The relevance, if any, of such events in children is unknown.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity studies of nafarelin were conducted in rats (24 months) at doses up to 100 mg/kg/day and mice (18 months) at doses up to 500 mg/kg/day using intramuscular doses (up to 110 times and 560 times the maximum recommended human intranasal dose, respectively). These multiples of the human dose are based on the relative bioavailability of the drug by the two routes of administration. As seen with other GnRH agonists, nafarelin acetate given to laboratory rodents at high doses for prolonged periods induced proliferative responses (hyperplasia and/or neoplasia) of endocrine organs. At 24 months, there was an increase in the incidence of pituitary tumors (adenoma/carcinoma) in high-dose female rats and a dose-related increase in male rats. There was an increase in pancreatic islet cell adenomas in both sexes, and in benign testicular and ovarian tumors in the treated groups. There was a dose-related increase in benign adrenal medullary tumors in treated female rats. In mice, there was a dose-related increase in Harderian gland tumors in males and an increase in pituitary adenomas in high-dose females. No metastases of these tumors were observed. It is known that tumorigenicity in rodents is particularly sensitive to hormonal stimulation.

Mutagenicity studies were performed with nafarelin acetate using bacterial, yeast, and mammalian systems. These studies provided no evidence of mutagenic potential.

Reproduction studies in male and female rats have shown full reversibility of fertility suppression when drug treatment was discontinued after continuous administration for up to 6 months. The effect of treatment of prepubertal rats on the subsequent reproductive performance of mature animals has not been investigated.

Pregnancy Category X. See †CONTRAINDICATIONS.† Intramuscular SYNAREL was administered to rats during the period of organogenesis at 0.4, 1.6, and 6.4 mg/kg/day (about 0.5, 2, and 7 times the maximum recommended human intranasal dose based on the relative bioavailability by the two routes of administration). An increase in major fetal abnormalities was observed in 4/80 fetuses at the highest dose. A similar, repeat study at the same doses in rats and studies in mice and rabbits at doses up to 600 mg/kg/day and 0.18 mg/kg/day, respectively, failed to demonstrate an increase in fetal abnormalities after administration during the period of organogenesis. In rats and rabbits, there was a dose-related increase in fetal mortality and a decrease in fetal weight with the highest dose.

It is not known whether SYNAREL is excreted in human milk. Because many drugs are excreted in human milk, and because the effects of SYNAREL on lactation and/or the breastfed child have not been determined, SYNAREL should not be used by nursing mothers.

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