Synarel (nafarelin acetate)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Nafarelin acetate, a synthetic decapeptide analog of gonadotropin-releasing hormone (GnRH, luteinizing hormone-releasing hormone, gonadorelin), is used for its endocrine effects.
Nafarelin acetate is a synthetic decapeptide analog of gonadotropin-releasing hormone (GnRH, luteinizing hormone-releasing hormone, gonadorelin) that is structurally related to goserelin, leuprolide, and triptorelin.
Nafarelin is a potent inhibitor of gonadotropin secretion when given continuously in therapeutic doses and has greater activity than naturally occurring GnRH. After initial administration of nafarelin, there is a transient surge in circulating levels of LH and follicle-stimulating hormone (FSH), testosterone, and estradiol. Following chronic and continuous administration of nafarelin (generally 4 weeks after initiation of therapy), a sustained decrease in LH and FSH secretion and a marked reduction of testicular and ovarian steroidogenesis are observed.
Consequently, physiologic functions and tissues dependent on gonadal steroids for maintenance become quiescent. In adult women, serum estradiol, FSH, and LH concentrations usually return to pretreatment levels following discontinuation of therapy.
In children with central precocious puberty receiving continuous administration of adequate doses of nafarelin, serum LH, testosterone, and estradiol concentrations return to prepubertal levels, resulting in suppression of secondary sexual characteristics and decreased rate of linear growth and skeletal maturation. These effects usually are reversible after cessation of therapy. Initial estrogen withdrawal bleeding may occur, generally within 6 weeks after therapy initiation; menstruation should cease thereafter.
Nafarelin acetate is commercially available as a nasal solution containing 2 mg of nafarelin per mL for administration via a metered spray pump.
Following intranasal administration, nafarelin is rapidly absorbed into systemic circulation. In adult women, bioavailability of a 400-mcg dose reportedly averages 2.8% (range: 1.2-5.6%).
USES: Nafarelin is used in women to treat a condition in which the tissue that normally lines the inside of the uterus grows in the wrong place (endometriosis). This medication helps to decrease the abnormal tissue and also the symptoms of endometriosis (such as pelvic pain, painful menstrual cramps, and pain during/after sex). This medication is also used by children to treat a certain type of early puberty (central precocious puberty, gonadotropin-dependent).
It helps to slow the bone aging and height growth rate so that both are near normal, and it helps to stop or reverse signs of early puberty (such as breast growth in girls, growth of sexual organs in boys). Nafarelin is similar to a natural hormone made by the body (gonadotropin-releasing hormone-GnRH). It works by decreasing the testosterone hormones in boys and estrogen hormones in women and girls.
Generic name: nafarelin acetate
Pronunciation: (NAF-a-REL-in AS-e-tate)
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Synarel
Indications
The following indications are listed for Synarel:
- Endometriosis
- Precocious Puberty
Also known as: Accelerated Sexual Maturity, Adenomyosis Externa, Endometriosis Externa.
Dosing
Dosage of nafarelin acetate is expressed in terms of nafarelin. After initial priming, the commercially available nasal pump delivers 200 mcg of nafarelin per spray and delivers approximately 60 sprays.
Missed doses may cause breakthrough bleeding or ovulation, or restart pubertal development. Full efficacy is dependent on dosage compliance for the full duration of treatment.
No dosing information is available for this tab.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
No pharmacokinetic drug interaction studies have been performed. The manufacturer states that because nafarelin is a peptide that is mainly degraded by peptidases and not by cytochrome P-450 (CYP) microsomal enzymes and because of the drug's limited protein binding, drug interactions are not expected to occur.
Administration of the topical nasal decongestant should be delayed until at least 2 hours after administration of nafarelin.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
Known hypersensitivity to nafarelin or any ingredient in the formulation, other gonadotropin-releasing hormone (GnRH) agonists, or GnRH. Known or suspected pregnancy or lactation. Abnormal vaginal bleeding of unknown etiology.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
Symptoms suggestive of drug sensitivity (e.g., shortness of breath, chest pain, urticaria, rash, pruritus) have been reported in 0.2% of women and 2.6% of children in clinical studies.
Adverse effects occurring in 10% or more of women include hot flushes (flashes), decreased libido, vaginal dryness, headache, emotional lability, acne, myalgia, reduction in breast size, and nasal irritation. Decreases in bone mineral density have occurred in women receiving nafarelin; concurrent use of hormone replacement therapy or bisphosphonates (e.g., alendronate) minimizes bone mineral loss associated with GnRH agonist therapy without compromising efficacy of these drugs in the management of endometriosis. (See Cautions: Endocrine Effects and see Precautions and Contraindications, in Leuprolide Acetate 68:18.08.)
Adverse effects reported in 3% or more of children include acne, transient breast enlargement, emotional lability, transient increases in pubic hair, body odor, seborrhea, hot flushes (flashes), rhinitis, vaginal bleeding, and white or brown vaginal discharge.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
No enhanced messaging available.
Safety and efficacy of nafarelin in children (younger than 18 years of age) for uses (e.g., endometriosis) other than the treatment of central precocious puberty have not been established.
Category X. (See Warnings: Fetal/Neonatal Morbidity and Mortality, in Cautions.)
Not known whether nafarelin is distributed into milk. Nafarelin should not be used in nursing women.
No enhanced messaging available.
ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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