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SYNAREL® (nafarelin acetate) Warnings and Precautions

WARNINGS

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 µg/day administered as 600 µg tid.

Psychiatric events have been reported in patients taking GnRH agonists. Postmarketing reports with this class of drugs includes symptoms of emotional lability, such as crying, irritability, impatience, anger, and aggression. Monitor for development or worsening of psychiatric symptoms during treatment with SYNAREL.

Post-marketing reports of convulsions have been observed in patients receiving GnRH agonists. These have included patients with a history of seizures, epilepsy, cerebrovascular disorders, central nervous system anomalies or tumors, and patients on concomitant medications that have been associated with convulsions such as bupropion and SSRIs. Convulsions have also been reported in patients in the absence of any of the conditions mentioned above.


WARNINGS

Safe use of nafarelin acetate in pregnancy has not been established clinically. Before starting treatment with SYNAREL, pregnancy must be excluded.

When used regularly at the recommended dose, SYNAREL usually inhibits ovulation and stops menstruation. Contraception is not insured, however, by taking SYNAREL, particularly if patients miss successive doses. Therefore, patients should use nonhormonal methods of contraception. Patients should be advised to see their physician if they believe they may be pregnant. If a patient becomes pregnant during treatment, the drug must be discontinued and the patient must be apprised of the potential risk to the fetus.


PRECAUTIONS

General

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.

Information for Patients, Patients' Parents or Guardians

An information pamphlet for patients is included with the product. Patients and their caregivers should be aware of the following information:

1. Reversibility of the suppressive effects of nafarelin has been demonstrated by the appearance or return of menses, by the return of pubertal gonadotropin and gonadal sex steroid levels, and/or by advancement of secondary sexual development. Semen analysis was normal in the two ejaculated specimens obtained thus far from boys who have been taken off therapy to resume puberty. Fertility has not been documented by pregnancies and the effect of long-term use of the drug on fertility is not known.

2. Patients and their caregivers should be adequately counseled to assure full compliance; irregular or incomplete daily doses may result in stimulation of the pituitary-gonadal axis.

3. Inform parents that reports of convulsions have been observed in patients receiving GnRH agonists. Patients with a history of seizures, epilepsy, cerebrovascular disorders, central nervous system anomalies or tumors, and patients on concomitant medications that have been associated with convulsions may be at increased risk [see Warnings].

4. Inform caregivers that reports of convulsions have been observed in patients receiving GnRH agonists. Patients with a history of seizures, epilepsy, cerebrovascular disorders, central nervous system anomalies or tumors, and patients on concomitant medications that have been associated with convulsions may be at increased risk [see Warnings].

5. During the first month of treatment with SYNAREL, some signs of puberty, e.g., vaginal bleeding or breast enlargement, may occur. This is the expected initial effect of the drug. Such changes should resolve soon after the first month. lf such resolution does not occur within the first two months of treatment, this may be due to lack of compliance or the presence of gonadotropin independent sexual precocity. If both possibilities are definitively excluded, the dose of SYNAREL may be increased to 1800 µg/day administered as 600 µg tid.

6. Patients with intercurrent rhinitis should consult their physician for the use of a topical nasal decongestant. If the use of a topical nasal decongestant is required during treatment with SYNAREL, the decongestant should not be used until at least 2 hours following dosing with SYNAREL.

Sneezing during or immediately after dosing with SYNAREL should be avoided, if possible, since this may impair drug absorption.

Drug Interactions

No pharmacokinetic-based drug-drug interaction studies have been conducted with SYNAREL. However, because nafarelin acetate is a peptide that is primarily degraded by peptidase and not by cytochrome P-450 enzymes, and the drug is only about 80% bound to plasma proteins at 4°C, drug interactions would not be expected to occur.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity studies of nafarelin were conducted in rats (24 months) at doses up to 100 µg/kg/day and mice (18 months) at doses up to 500 µg/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

Teratogenic Effects

See Contraindications. Intramuscular SYNAREL was administered to rats during the period of organogenesis at 0.4, 1.6, and 6.4 µg/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 µg/kg/day and 0.18 µg/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.

Nursing Mothers

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.


PRECAUTIONS

General

As with other drugs that stimulate the release of gonadotropins or that induce ovulation, 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 patients 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.

Information for Patients

An information pamphlet for patients is included with the product. Patients should be aware of the following information:

1. Since menstruation should stop with effective doses of SYNAREL, the patient should notify her physician if regular menstruation persists. The cause of vaginal spotting, bleeding or menstruation could be noncompliance with the treatment regimen, or it could be that a higher dose of the drug is required to achieve amenorrhea. The patient should be questioned regarding her compliance. If she is careful and compliant, and menstruation persists to the second month, consideration should be given to doubling the dose of SYNAREL. If the patient has missed several doses, she should be counseled on the importance of taking SYNAREL regularly as prescribed.

2. Patients should not use SYNAREL if they are pregnant, breastfeeding, have undiagnosed abnormal vaginal bleeding, or are allergic to any of the ingredients in SYNAREL.

3. Safe use of the drug in pregnancy has not been established clinically. Therefore, a nonhormonal method of contraception should be used during treatment. Patients should be advised that if they miss successive doses of SYNAREL, breakthrough bleeding or ovulation may occur with the potential for conception. If a patient becomes pregnant during treatment, she should discontinue treatment and consult her physician.

4. Those adverse events occurring most frequently in clinical studies with SYNAREL are associated with hypoestrogenism; the most frequently reported are hot flashes, headaches, emotional lability, decreased libido, vaginal dryness, acne, myalgia, and reduction in breast size. Estrogen levels returned to normal after treatment was discontinued. Nasal irritation occurred in about 10% of all patients who used intranasal nafarelin.

5. The induced hypoestrogenic state results in a small loss in bone density over the course of treatment, some of which may not be reversible. During one six-month treatment period, this bone loss should not be important. In patients with major risk factors for decreased bone mineral content such as chronic alcohol and/or tobacco use, strong family history of osteoporosis, or chronic use of drugs that can reduce bone mass such as anticonvulsants or corticosteroids, therapy with SYNAREL may pose an additional risk. In these patients the risks and benefits must be weighed carefully before therapy with SYNAREL is instituted. Repeated courses of treatment with gonadotropin-releasing hormone analogs are not advisable in patients with major risk factors for loss of bone mineral content.

6. Patients with intercurrent rhinitis should consult their physician for the use of a topical nasal decongestant. If the use of a topical nasal decongestant is required during treatment with SYNAREL, the decongestant should not be used until at least 2 hours following dosing with SYNAREL.

Sneezing during or immediately after dosing with SYNAREL should be avoided, if possible, since this may impair drug absorption.

7. Retreatment cannot be recommended since safety data beyond 6 months are not available.

Drug Interactions

No pharmacokinetic-based drug-drug interaction studies have been conducted with SYNAREL. However, because nafarelin acetate is a peptide that is primarily degraded by peptidase and not by cytochrome P-450 enzymes, and the drug is only about 80% bound to plasma proteins at 4°C, drug interactions would not be expected to occur.

Drug/Laboratory Test Interactions

Administration of SYNAREL in therapeutic doses results in suppression of the pituitary-gonadal system. Normal function is usually restored within 4 to 8 weeks after treatment is discontinued. Therefore, diagnostic tests of pituitary gonadotropic and gonadal functions conducted during treatment and up to 4 to 8 weeks after discontinuation of therapy with SYNAREL may be misleading.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity studies of nafarelin were conducted in rats (24 months) at doses up to 100 µg/kg/day and mice (18 months) at doses up to 500 µg/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

Teratogenic Effects

See Contraindications. Intramuscular SYNAREL was administered to rats during the period of organogenesis at 0.4, 1.6, and 6.4 µg/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 µg/kg/day and 0.18 µg/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.

Nursing Mothers

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.

Pediatric Use

Safety and effectiveness of SYNAREL for endometriosis in patients younger than 18 years have not been established.

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