This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
An important difference between leuprolide and ganirelix is that ganirelix: 
Select and explain. 
A. Can be given orally, B. Immediately reduces gonadotropin secretion, C. Must be given in a Pulsatile fashion, D. Initially stimulates release of LH and FSH
B: Immediately reduces gonadotropin secretion
Answer: B: Immediately reduces gonadotropin secretion 
Explanation: GnRH agonists like leuprolide, goserelin and nafarelin etc. are used by parenteral route. Continuous administration of these agents decreases gonadotropin secretion whereas pulsatile administration increases the secretion. When used continuously even then first few doses cause increased secretion of gonadotropins (LH and FSH) leading to flare up reaction in prostatic carcinoma.
GnRH antagonists like cetrorelix and ganirelix are also used by parenteral route but these drugs immediately reduce gonadotropin secretion.