Cetrorelix

Cetrorelix is a decapeptide, meaning it consists of ten amino acids. Its chemical formula is C70H92ClN17O14, and it has a molecular weight of approximately 1431.06 g/mol . The structure of Cetrorelix allows it to effectively bind to GnRH receptors, inhibiting their activity.

Cetrorelix works by blocking the action of GnRH on the pituitary gland. GnRH is responsible for stimulating the release of LH and follicle-stimulating hormone (FSH) from the anterior pituitary . By inhibiting GnRH, Cetrorelix prevents the LH surge that triggers ovulation, thereby controlling the timing of ovulation during assisted reproductive procedures .

Cetrorelix is primarily used in controlled ovarian stimulation protocols for in vitro fertilization (IVF). By preventing premature LH surges, it ensures that eggs are not released before they are fully mature and ready for fertilization . This increases the chances of successful fertilization and embryo development.

Additionally, Cetrorelix has been explored for use in treating hormone-sensitive cancers such as prostate and breast cancer, as well as benign gynecological disorders like endometriosis and uterine fibroids .

Cetrorelix is administered via subcutaneous injection. It is available in two dosing regimens: a single 3 mg dose or multiple 0.25 mg daily doses . The choice of regimen depends on the specific requirements of the patient’s treatment protocol.

Cetrorelix has a bioavailability of approximately 85% when administered subcutaneously . Its elimination half-life varies depending on the dosage: around 62.8 hours for a single 3 mg dose and 20.6 hours for multiple 0.25 mg doses . The drug is primarily excreted through feces and urine .

Common side effects of Cetrorelix include injection site reactions, nausea, headache, and abdominal pain . It is contraindicated in patients with severe renal impairment and those with known hypersensitivity to GnRH or any of its analogs .