Gonadotropin Releasing Hormone (GnRH) Agonists & Antagonists
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GnRH Analogs
Indications
- These drugs are used in urogynecological diasese (eg, prostate, ovarian) and ovulation stimulation/suppression, amongst other things.
- For example, they are used in the treatment/suppression of:
- Prostate cancer (as part of androgen deprivation therapy)
- Endometriosis, controlled ovulation in ART, and uterine fibroid therapy,
- Children with central precocious puberty or to block endogenous puberty in transgender adolescents.
- They are sometimes used intermittently to increase FSH & LH levels, but this is less common.
Side Effects
- Side effects are related to continuous treatment that leads to hypoestrogenic states – think of "menopause-like" symptoms: hot flashes, headaches, sweating, and increased risk of osteoporosis.
Examples
- Examples of these drugs include leuprolide and the "relins": goserelin, nafarelin, histrelin; route of administration varies.
- When given in pulsatile fashion, they act as agonists.
- When given in a steady state, they act as antagonists.
GnRH Antagonists
- GnRH receptor antagonists block GnRH receptors and inhibit FSH & LH production.
- Examples of these drugs end in "relix": ganirelix, cetrorelix, and egarelix (route of administration varies).
- They are used to delay ovulation in ART (prevent the LH surge), and in prostate cancer (these drugs avoid the initial testosterone surge caused by GnRH analogs).