Cetrorelix is a synthetic decapeptide that acts as a potent, competitive antagonist of the gonadotropin-releasing hormone (GnRH) receptor. It is used in assisted reproductive technology (ART) cycles to prevent premature luteinizing hormone (LH) surges, thereby allowing controlled ovarian stimulation. It is administered subcutaneously.
Adult: 0.25 mg administered subcutaneously once daily. Initiation: Start on Day 5 or 6 of ovarian stimulation with FSH/hMG (or when the leading follicle reaches approximately 12-14 mm in diameter). Continue daily until the day of hCG (human chorionic gonadotropin) administration for final oocyte maturation.
Note: For subcutaneous injection only. Reconstitute the 0.25 mg vial with 1 ml of provided solvent (Sodium Chloride solution). Gently swirl to dissolve. Do not shake vigorously. Administer in the lower abdomen (avoiding the navel area) or upper thigh. Rotate injection sites daily. Use immediately after reconstitution. Discard any unused solution.
Cetrorelix competitively binds to the pituitary GnRH receptors. This blockade inhibits the secretion of gonadotropins—luteinizing hormone (LH) and, to a lesser extent, follicle-stimulating hormone (FSH)—in a dose-dependent manner. By preventing the endogenous mid-cycle LH surge, it allows for the continuation of exogenous gonadotropin therapy without premature ovulation or luteinization.
Pregnancy: CONTRANDICATED. Cetrorelix is used to prevent pregnancy during an ART cycle until embryo transfer. It may cause fetal harm. If pregnancy occurs prior to or during therapy, discontinue immediately. Pregnancy should be excluded before starting treatment.
Driving: No known effects on driving ability. However, patients should be cautioned about potential dizziness or fatigue.
| Other GnRH analogues (Agonists like Leuprolide, Buserelin) | Pharmacological antagonism; concurrent use is not recommended. | Major |
| Gonadotropins (FSH, hMG, hCG) | Used therapeutically in sequence/combination in ART protocols. Cetrorelix prevents premature LH surge during gonadotropin stimulation. | Therapeutic |
| Drugs metabolized by CYP450 enzymes | No known significant interactions as cetrorelix is not metabolized by CYP enzymes. | Minor |