Chemical Identity

Property	Value
Chemical Formula	C80H113N18O15Cl
Molecular Weight	1570.29 Da
CAS Number	124904-93-4
Peptide Class	GnRH Antagonist (Decapeptide)
Route	Subcutaneous injection

Structure

Ganirelix is a synthetic decapeptide GnRH antagonist with modifications at positions 1, 2, 3, 6, 8, and 10 of the native GnRH sequence. It contains D-amino acids, N-alkylated residues, and a ureido linkage that enhance receptor binding and resist enzymatic degradation.

Mechanism of Action

Ganirelix competitively blocks GnRH receptors, immediately suppressing LH and FSH secretion. In IVF, this prevents premature ovulation while allowing continued follicle development under exogenous FSH stimulation. The competitive blockade allows rapid reversibility upon discontinuation.

Clinical Applications

• Controlled ovarian stimulation: Prevention of premature LH surge in IVF/ICSI
• Oocyte retrieval timing: Allows precise timing of hCG trigger
• Multiple follicle development: Prevents premature luteinization
• GnRH agonist trigger protocols: Compatible with dual trigger

Pharmacokinetics

• Half-life: 16 hours
• Tmax: 1-2 hours
• Bioavailability: 91% (subcutaneous)
• Metabolism: Proteolytic degradation
• Dose: 0.25 mg daily subcutaneous
• Route: Subcutaneous

Safety and Side Effects

Local injection site reactions, headache, nausea, and ovarian hyperstimulation syndrome (related to IVF protocol, not ganirelix specifically). Well-tolerated with minimal systemic effects.

References

• The Ganirelix Dose-Finding Study Group (1998). A double-blind dose-finding study of ganirelix. Human Reproduction, 13, 2127-2132.
• Borm, G., & Mannaerts, B. (2000). Ganirelix in IVF. Human Reproduction, 15, 144-150.