TABLE 3.

Pharmacological Profiles of GnRH Agonists and Antagonists

Clinical Parameter	GnRH Agonists	GnRH Antagonists
Initial testosterone (T) surge (which may cause clinical flare)	Yes	No
T suppression onset	3 d	Immediate
Castration achieved 28 d	3–4 d
T microsurges	Yes	No
Follicle-stimulating hormone suppression	Partial	Rapid and sustained
Prostate-specific antigen suppression	Slower through Day 60 ±	Faster in first 2 mo

Adapted from Shore ND et al,¹² Klotz L et al,¹⁵ Crawford ED et al,¹⁸ and McLeod D.²⁰