Nafarelin


Generic Medicine Info
Indications and Dosage
Nasal
Pituitary desensitisation before ovulation induction with gonadotrophins
Adult: 400 mcg bid, given as 1 spray to each nostril in the morning and 1 spray to each nostril in the evening, starting either on the early follicular phase (day 2) or midluteal phase (day 21) of menstrual cycle, continued until down-regulation is achieved. Max treatment duration: 12 wk.

Nasal
Endometriosis
Adult: 200 mcg bid, given as 1 spray (200 mcg) in 1 nostril in the morning and 1 spray in the other nostril in the evening, starting on days 2-4 of menstrual cycle. Dose may be doubled after 2 mth if symptoms persist. Max treatment duration: 6 mth.

Nasal
Central precocious puberty
Child: 800 mcg bid, given as 2 sprays (400 mcg) into each nostril in the morning and 2 sprays into each nostril in the evening. Dose may be increased up to 600 mcg tid, if necessary depending on response.
Contraindications
Undiagnosed abnormal vag bleeding. Pregnancy and lactation.
Special Precautions
Patient w/ pituitary adenoma, polycystic ovarian disease, psychiatric comorbidities, risk factors for BMD, intercurrent rhinitis; history of seizures, cerebrovascular disorders, CNS anomalies or tumours. Childn.
Adverse Reactions
Significant: Ovarian cysts, risk of cystic enlargement, decreased BMD, pituitary apoplexy (e.g. sudden headache, CV collapse, vomiting, visual/mental status change); psychiatric events (e.g. emotional lability, irritability, aggression, depression), seizures, convulsions, vag bleeding, breast enlargement.
Nervous: Insomnia, paraesthesia.
CV: Oedema, HTN, hypotension.
Resp: Rhinitis, nasal mucosal irritation.
Genitourinary: Vulvovaginal dryness, vag discharge, uterine haemorrhage, ovarian hyperstimulation syndrome.
Endocrine: Hot flushes, variable libido, artificial menopause, hypertriglyceridaemia, breast atrophy, hypercholesterolaemia, wt gain/loss, oestrogen deficiency.
Haematologic: WBC decrease, eosinophilia.
Musculoskeletal: Myalgia, arthralgia.
Dermatologic: Acne vulgaris, hypertrichosis, body odor, seborrhoea, hirsutism, alopecia.
Immunologic: Hypersensitivity reactions (e.g. chest pain, urticaria, pruritus, dyspnoea, rash).
Others: Hyperphosphataemia, hypocalcaemia.
Monitoring Parameters
Monitor BMD (prior to therapy and before retreatment), FSH and LH blood levels, bone age measurement, development or worsening of psychiatric symptoms, menstruation, vag bleeding/spotting.
Drug Interactions
May enhance the effect of corifollitropin alfa.
Lab Interference
May give misleading result in the diagnostic test for pituitary gonadotropic and gonadal functions up to 4-8 wk after treatment discontinuation.
Action
Description:
Mechanism of Action: Nafarelin is a gonadorelin analogue. It produces an initial phase of stimulation followed by down-regulation of gonadotrophin-releasing hormone receptors, thus reducing the release of FSH and LH, leading to inhibition of androgen and oestrogen production.
Pharmacokinetics:
Absorption: Rapidly absorbed intranasally. Bioavailability: Approx 3%. Time to peak plasma concentration: W/in 20 min.
Distribution: Plasma protein binding: Approx 80%, mainly to albumin.
Metabolism: Metabolised by peptidases to form metabolites.
Excretion: Via urine (44-55%, approx 3% as unchanged drug); faeces (19-44%). Elimination half-life: Approx 3 hr.
Chemical Structure

Chemical Structure Image
Nafarelin

Source: National Center for Biotechnology Information. PubChem Database. Nafarelin, CID=25077405, https://pubchem.ncbi.nlm.nih.gov/compound/Nafarelin (accessed on Jan. 22, 2020)

Storage
Store below 25°C. Protect from light. Do not freeze.
MIMS Class
Trophic Hormones & Related Synthetic Drugs
ATC Classification
H01CA02 - nafarelin ; Belongs to the class of gonadotropin-releasing hormones. Used in hypothalamic hormone preparations.
References
Anon. Nafarelin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/10/2017.

Buckingham R (ed). Nafarelin Acetate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/10/2017.

Joint Formulary Committee. Nafarelin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/10/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Nafarelin Acetate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 05/10/2017.

Synarel Spray Metered (G.D. Searle LLC Division of Pfizer Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 05/10/2017.

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