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INTRODUCTION

nafarelin (na-fare-e-lin)

Synarel

Classification

Therapeutic: hormones

Pharmacologic: gonadotropin-releasing hormones

Indications

Management of endometriosis. Management of central precocious puberty (gonadotropin-dependent) in children.

Action

Acts as a synthetic analogue of gonadotropin-releasing hormone (GnRH). Initially increases pituitary production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which cause ovarian steroid production. Chronic administration leads to decreased production of gonadotropins. Endometriotic lesions are sensitive to ovarian hormones. Therapeutic Effects: Reduction in lesions and associated pain in endometriosis. Arrest and regression of puberty in children with central precocious puberty.

Adverse Reactions/Side Effects

CNS: emotional instability, headaches, depression, insomnia. EENT: nasal irritation. CV: edema. GU: vaginal dryness. Derm: acne, hirsutism, seborrhea. Endo: cessation of menses, impaired fertility, reduced breast size. MS: decreased bone density, myalgia. Misc: decreased libido, hot flashes, hypersensitivity reactions, weight gain.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

  • Monitor signs of hypersensitivity reactions, including pulmonary symptoms (tightness in the throat and chest, wheezing, cough, dyspnea) or skin reactions (rash, pruritus, urticaria). Notify physician immediately if these reactions occur.

  • Assess peripheral edema using girth measurements, volume displacement, and measurement of pitting edema (See Appendix N). Report increased swelling in feet and ankles due to peripheral vasodilation.

  • Monitor personality or behavioral changes, including emotional instability, depression, sleep loss, or other changes in mood. Notify physician if these changes become problematic.

  • Assess any muscle pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.

  • Periodically assess body weight and other anthropometric measures (body mass index, body composition). Report a rapid or unexplained weight gain or increased body fat.

Interventions

  • Institute weight-bearing and resistance exercises as tolerated to maintain bone mineral density and prevent demineralization.

Patient/Client-Related Instruction

  • Instruct patient or family/caregivers to report other troublesome side effects such as severe or prolonged headache, nasal irritation, hot flashes, menstrual irregularities, vaginal dryness, hot flashes, reduced breast size, decreased libido, or skin reactions (acne, oily skin increased hair growth).

Pharmacokinetics

Absorption: Well absorbed following intranasal administration.

Distribution: Unknown.

Metabolism and Excretion: 20–40% excreted in feces; 3% excreted unchanged by the kidneys.

Half-life: 3 hr.

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TIME/ACTION PROFILE (decreased ovarian steroid production)

ROUTE ONSET PEAK DURATION
Intranasal within 4 wk 3–4 wk 3–6 mo*

*Relief of symptoms of endometriosis following discontinuation.

Contraindications/Precautions

Contraindicated in: Hypersensitivity to GnRH, its analogues, or sorbitol; Pregnancy or lactation.

Use Cautiously in: Rhinitis.

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