Cetrorelix

Cetrorelix (INN) is a synthetic decapeptide with potent gonadotropin-releasing hormone antagonist properties. It is primarily used in assisted reproduction to prevent premature luteinizing hormone (LH) surges in women undergoing controlled ovarian stimulation (COS). Cetrorelix is marketed under the brand name Cetrotide, among others.

Medical Uses

Cetrorelix is used in fertility medicine to control the timing of ovulation in women undergoing fertility treatments. By inhibiting the action of gonadotropin-releasing hormone (GnRH) on the pituitary gland, it prevents the LH surge that would otherwise trigger ovulation prematurely. This allows for the timing of ovulation to be controlled, which is crucial for the timing of egg retrieval in procedures such as in vitro fertilization (IVF).

Mechanism of Action

Cetrorelix works by competitively blocking the receptors of GnRH on the anterior pituitary gland. This inhibition prevents the release of LH and follicle-stimulating hormone (FSH), which are necessary for ovulation and the development of the corpus luteum. By preventing the LH surge, cetrorelix allows for the size and number of follicles to be increased and controlled during fertility treatments.

Pharmacokinetics

Cetrorelix is administered via subcutaneous injection. It has a rapid onset of action, with gonadotropin suppression occurring shortly after administration. The duration of action is dose-dependent, but it generally maintains its effect for several days, making it suitable for use in controlled ovarian stimulation protocols.

Adverse Effects

Common adverse effects of cetrorelix include local reactions at the injection site, such as redness, swelling, and itching. Less commonly, patients may experience headaches, nausea, and generalized allergic reactions. Due to its mechanism of action, cetrorelix may also cause a reduction in estrogen levels, leading to symptoms associated with decreased estrogen, such as hot flashes.

Contraindications

Cetrorelix is contraindicated in patients with known hypersensitivity to cetrorelix or any of its components. It should also be used with caution in patients with severe renal impairment due to the lack of comprehensive studies in this population.

Interactions

There are no known significant drug interactions with cetrorelix. However, as with all medications, it is important to inform healthcare providers of all medications and supplements being taken prior to starting treatment with cetrorelix.

Pharmacodynamics

Cetrorelix exhibits its effect through a high affinity for GnRH receptors, leading to a rapid decrease in circulating levels of LH and FSH. This decrease in gonadotropins prevents premature ovulation, allowing for the development of multiple follicles during fertility treatments.

History

Cetrorelix was developed in the late 20th century as part of the search for more effective and safer fertility treatments. It was one of the first GnRH antagonists to be widely used in clinical practice, offering an alternative to the GnRH agonists that were previously used for the same purpose.

Future Directions

Research continues into the development of new and improved GnRH antagonists, with the goal of reducing side effects, improving patient convenience, and increasing efficacy. Cetrorelix remains an important tool in fertility treatments, but ongoing studies aim to further optimize the use of GnRH antagonists in reproductive medicine.