Side by side

1. 1.Competitively blocks pituitary GnRH receptors.
2. 2.LH and FSH release falls within hours rather than weeks.
3. 3.Testosterone reaches castrate levels within a few days, with no initial surge.
4. 4.No receptor desensitisation is required, unlike agonists.
5. 5.Blocks the trophic signal to prostate cancer cells, which depend on androgen receptor signalling.

• Advanced prostate cancer
• Patients with spinal metastases or urinary obstruction where flare would be dangerous
• Comparison against leuprolide in randomised phase 3 trials

• Castrate testosterone within about three days, faster than agonists
• Sustained suppression to castrate level over 12 months in trials
• PSA reduction comparable to leuprolide
• Injection-site reactions are the most common adverse effect

• Injection-site pain, swelling and erythema, often lasting days
• Hot flushes
• Weight gain
• Raised liver enzymes
• Fatigue
• Reduced libido and erectile dysfunction
• Bone density loss with prolonged use

Research context only - prescription medicine. Licensed dosing is a 240 mg subcutaneous loading dose given as two injections, followed by 80 mg subcutaneously every 28 days; phase 3 trials measured testosterone suppression below 50 ng/dL at 3, 6 and 12 months.

Research context only