This monograph describes a medication approved for use in Canada by the Therapeutic Products Directorate, a division of Health Canada’s Health Products and Food Branch. The medication is not approved by the United States Food and Drug Administration; however, a similar formulation carrying a different generic or brand name might be available in the US.
luteinizing hormone-releasing hormone (LHRH) analogues
Acts as a synthetic analog of endogenous gonadotropin-releasing hormone (GnRH/LHRH). Chronic use results in inhibited secretion of gonadotropin release and gonadal steroid production. The overall effect is due to down-regulation of pituitary LHRH receptors. In males, testosterone synthesis and release is decreased. In females, secretion of estrogen in decreased.
Absorption: Subcut– 70%; intranasal– 1–3%; implant– drug is slowly absorbed over 2–3 mo.
Distribution: Accumulates in liver, kidneys and anterior pituitary lobe; enters breast milk in small amounts.
Metabolism and Excretion: Metabolized in liver, kidneys and by enzymes on membranes in the pituitary gland.
Half-life: Subcut– 80 min; intranasal– 1–2 hr; implant– 20–30 days.
|prostate cancer †||7 days||4 mo||until discontinuation|
|endometriosis ‡(intranasal)||unknown||unknown||duration of treatment|
Use Cautiously in:
CNS: depression, dizziness
Endo: glucose intolerance
Local: injection site reactions
MS: osteoporosis (long-term use)
Misc: transient exacerbation of metastatic prostate cancer or endometriosis
CNS: headache (nasal solution)
EENT: nasal irritation (nasal spray)
GU: ↓ libido, impotence
Derm: hot flushes
Endo: gynecomastia, testosterone flair
MS: bone pain
CNS: headache, weakness, insomnia
GI: constipation, gastrointestinal disorders, nausea
GU: ↓ libido, vaginal dryness, menorrhagia
Derm: hot flushes, acne
Endo: supression of ovulation
MS: back pain
* CAPITALS indicate life-threatening.
Underline indicate most frequent.
Risk of serious arrhythmias may be ↑ by concurrent amiodarone, disopyramide, dofetilide, flecainide ibutilide, propafenone quinidine, sotalol, antipsychotics (including chlorpromazine) antidepressants (including amitrypline and nortriptyline ), opioids (including methadone ), macrolide anti-infectives (including azithromycin, erythromycin and clarithromycin ), fluoroquinolones (including moxifloxacin ), azole antifungals, 5-HT3 antagonists (including ondansetron ), beta-2 receptor agonists (including salbutamol ), pentamidine, and quinine.
SC (Adults): Initial treatment– 500 mcg every 8 hr for 7 days, Maintenance treatment– 200 mcg daily.
Intranasal (Adults): Maintenance treatment– 400 mcg (200 mcg in each nostril) 3 times daily.
Subcut implant: (Adults): 6.3 mg every 2 mo or 9.45 mg every 3 mo.
Intranasal (Adults): 400 mcg (200 mcg in each nostril) 3 times daily. Treatment is usually continued for 6 mo; not to exceed 9 mo.
Solution for subcutaneous injection (contains benzyl alcohol): 1000 mcg/mL
Intranasal Solution: 1000 mcg/mL (delivers 100 mcg per actuation)
Subcutaneous implant (depot): 6.3 mg (2–mo implant), 9.45 mg (3–mo implant)
Lab Test Considerations: Monitor serum testosterone levels every 3 mo during treatment with male patients. When treatment begins, testosterone levels can temporarily markedly ↑ and patients may need another medication to ↓ levels.
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