Gonadotropin Releasing Hormone Analog (GnRH-a)

Classification

Synthetic nonapeptide analog of naturally occurring gonadotropin releasing hormone

Brand Names

Lupron©, Lupron Depot©, Goserelin©, Naferelin©, Synarel©, Zoladex©

Form

Subcutaneous or intramuscular injection (Lupron, Antagon); nasal spray (Naferelin, Synarel); skin-implants (Goserelin, Zoladex)

Indications

Uterine fibroids; Endometriosis; Demonstrated weak hormonal signal between the hypothalamus, pituitary, and ovarian systems with:

  • no current pregnancy
  • no hypersensitivity to GnRH or related drugs, or to benzyl alcohol
  • no abnormal vaginal bleeding

Used for

Endometriosis clinical symptoms; Synchronizing ovulatory cycles intended for fertility treatment (Controlled ovarian hyperstimulation or COH)

How does it work?

Suppresses pituitary secretion of gonadotropins (reproductive hormones) and halts menstrual cycle. Estrogen level decreases to menopause levels. Endometrium does not grow, ovulation does not occur.

Suggested Evaluations

Pre-RX

  • existence of current pregnancy
  • urinary tract obstruction
  • testosterone levels

During RX

  • serum testosterone & acid phosphatase levels
  • estrogen level

Usual Dosage

  • Injectables - From 3.75 mg once a month for six months to 11.25 mg every three months for six months (if intramuscular), or 1 mg subcutaneous once daily during early to mid-follicular phase, depending on diagnosis.
  • Nasal Sprays - One (1) 200 mcg spray into one nostril in the morning, and one spray in the other nostril in evening, for 6 months.
  • Implants - One (1) 3.6 mg implant injected under skin in upper abdomen every 28 days for six months.

Instructions

Injectables
Follow instructions for injectable drugs.
Nasal Sprays
Begin treatment on Day 2, 3, or 4 of menstrual cycle. Do not double doses if missed a dose.

Common side effects

  • Hot flashes
  • Night sweats
  • Headache
  • Emotional irritability
  • Breast size changes
  • Decreased libido
  • Acne
  • Vaginal dryness
  • Sore muscles

Side effects to report to your doctor

  • Heart palpitations
  • Extreme anxiety or depression
  • Shortness of breath or tight chest
  • Numbness or tingling of hands or feet
  • Skin rash, hives, or itching
  • Abdominal pain or swelling

Precautions

  • Category X: If taken during pregnancy, may cause birth defects.
  • Should not be used by women who are breastfeeding.
  • Results in small loss in bone density, some of which may not be reversible. Patients with osteoporosis risk factors are advised to avoid GnRH-a use beyond six months.
  • May cause temporary increase in endometriosis pain at beginning of treatment.

Drug interactions or incompatibility

No known drug interactions

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