1. Clinical Overview
Ganirelix acetate is a synthetic decapeptide and a potent, competitive antagonist of the gonadotropin-releasing hormone (GnRH) receptor. It is used in controlled ovarian stimulation (COS) protocols for assisted reproductive technology (ART) to prevent premature luteinizing hormone (LH) surges, thereby preventing premature ovulation and allowing for proper follicular maturation and oocyte retrieval.
| Onset | Duration | Bioavailability |
|---|---|---|
| Rapid, within 1-2 hours of subcutaneous administration. | Approximately 24 hours, requiring daily administration. | Approximately 91% following subcutaneous injection. |
2. Mechanism of Action
Ganirelix competitively blocks the pituitary GnRH receptors. This immediate blockade inhibits the secretion of gonadotropins—Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH)—from the anterior pituitary. By suppressing the mid-cycle LH surge, it prevents premature luteinization and ovulation during controlled ovarian stimulation, allowing for the continued growth of multiple follicles under exogenous gonadotropin therapy.
3. Indications & Uses
- Prevention of premature luteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation (COH) for assisted reproductive technology (ART) procedures like In Vitro Fertilization (IVF) or Intracytoplasmic Sperm Injection (ICSI).
4. Dosage & Administration
Adult Dosage: 0.25 mg (250 micrograms) administered subcutaneously once daily. Initiation: Start on Day 6 of ovarian stimulation with FSH/hMG (or when the leading follicle reaches approximately 12-14 mm in diameter as per clinic protocol). Continue daily until the day of hCG (human chorionic gonadotropin) administration for final oocyte maturation.
Administration: For subcutaneous use only. Administer in the lower abdomen (alternating sites), at least 1 inch away from the navel. Ensure the solution is clear and colorless. Use pre-filled syringe or reconstituted vial as per instructions. Rotate injection sites daily. Administer at approximately the same time each day.
5. Side Effects
Common side effects may include:
- Injection site reactions (pain, redness, swelling, itching, bruising) - very common (>10%).
- Headache.
- Nausea.
- Abdominal pain.
- Dyspepsia.
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other GnRH analogs (Agonists like Leuprolide, Buserelin) | Pharmacological antagonism; concurrent use is contraindicated. | Major |
| Gonadotropins (FSH, hMG, hCG) | Used therapeutically in sequence. Ganirelix is used to prevent premature LH surge during gonadotropin stimulation. No adverse pharmacokinetic interaction. | Moderate (Therapeutic sequence) |
| Oral Contraceptives, Estrogens, Androgens | May interfere with the efficacy of the controlled ovarian stimulation protocol. Should be discontinued prior to starting ART cycle. | Major |
| Glucocorticoids | High doses may interfere with the hypothalamic-pituitary-ovarian axis. Use with caution. | Moderate |
7. Patient Counselling
- DO administer subcutaneously in the lower abdomen as trained.
- DO rotate injection sites daily to minimize reactions.
- DO administer at roughly the same time each day.
- DO store prefilled syringes in the refrigerator (2°C to 8°C). Protect from light.
- DONT administer intravenously or intramuscularly.
- DONT use if the solution is cloudy or contains particles.
- DONT stop medication without consulting your fertility specialist.
- DONT try to conceive naturally during this treatment cycle without guidance.
8. Toxicology & Storage
Overdose: No specific cases reported. Based on mechanism, potential symptoms may include excessive suppression of LH/FSH leading to lack of follicular growth or support of corpus luteum if administered post-ovulation. Injection site reactions may be more pronounced.
Storage: Store in a refrigerator at 2°C to 8°C. Do not freeze. Keep the pre-filled syringe in the outer carton to protect from light. If needed, the syringe can be kept at room temperature (below 25°C) for a maximum of 30 days. Do not expose to direct heat or sunlight. Keep out of reach and sight of children.