Leuprolide
**Leuprolide** is a synthetic nonapeptide analog of gonadotropin-releasing hormone (GnRH). In veterinary medicine, it is primarily utilized for the medical management of **adrenal-associated endocrinopathy in ferrets** and to suppress **inappropriate egg-laying or reproductive disorders in captive birds**. Key clinical points: * **Ferret Adrenal Disease**: Unlike dogs, ferret adrenal disease is driven by excess sex hormones (androgens/estrogens) rather than cortisol. Leuprolide effectively suppresses the hormonal axis responsible for these clinical signs (e.g., alopecia, vulvar swelling, pruritus). * **Formulations**: It is most commonly administered as a long-acting **depot injection** (microspheres) that provides sustained release over 1, 3, or 4 months. * **Cost**: The medication is extremely expensive, though compounding pharmacies often divide human vials into smaller, more affordable aliquots for exotic animal use. * **Safety**: It is highly teratogenic and strictly contraindicated in pregnancy.
Mecanismo: Leuprolide acts as a **luteinizing hormone-releasing hormone (LHRH/GnRH) agonist**. * **Initial Phase (Flare)**: Upon initial administration, it stimulates the pituitary gland, causing a transient surge in **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)**. * **Downregulation Phase**: Continuous exposure via depot formulation causes profound downregulation and desensitization of **GnRH receptors** in the anterior pituitary. * **Suppression**: This negative feedback → halts the release of **LH** and **FSH** → drastically decreases serum levels of gonadal steroids (**estrogen** and **androgens**), thereby resolving hormonally driven clinical signs.
Dosificación por especie
- Adrenal associated endocrinopathy (30-day formulation) · 100 micrograms/kg (females) or 200 micrograms/kg (males) · IM · q30d · Lifelong/Ongoing · Proven effective for management of the disease.
- Adrenal associated endocrinopathy (3-month formulation) · 1 mg (total dose) · IM · every 60-75 days · Lifelong/Ongoing · Length of control in intact ferrets in Spring; may be useful for annual Dec/Feb suppression.
- Adrenal associated endocrinopathy (4-month formulation) · 2 mg (total dose) · IM · every 70-80 days · Lifelong/Ongoing · Anecdotal time before signs reappear; may be useful for annual Dec/Feb suppression.
- Adrenal associated endocrinopathy (30-day formulation, weight-based) · <1 kg: 100 micrograms; >1 kg: 200 micrograms · IM · q30d · Lifelong/Ongoing · Generally diluted from original concentration to negate muscle necrosis. Diluted form appears active after freezing for a year (though manufacturer advises against freezing).
- Adrenal associated endocrinopathy (1-month depot form) · 100-250 micrograms/kg · IM · every 4 weeks until signs resolve, then every 4-8 weeks as needed · Lifelong · Larger ferrets may require the higher dosage range.
- Inappropriate egg laying in Cockatiels (if management changes fail) · 800 micrograms/kg IM every 2 weeks for 3 injections · IM · q14d · 3 injections · Often effective at reducing reproduction at least in the short-term.
- Inhibit egg laying in pet birds · 100 micrograms/kg per day. Multiply dose by number of days for effect and give once monthly (e.g., 100 mcg/kg x 28 days = 2800 mcg/kg dose) · IM · q30d · Monthly
Vías de administración
Contraindicaciones
- Pregnancy (FDA Category X - major fetal abnormalities may result)
- Nursing/lactating animals (use with extreme caution, excretion in milk is unknown)
Efectos adversos
- Pain or irritation at the injection site
- Dyspnea (reported in ferrets)
- Lethargy (reported in ferrets)
- Tachyphylaxis (higher dosages required over time to obtain the same effect in ferrets)
- Transient worsening of clinical signs (flare effect) shortly after initial administration
Monitorización
- Ferrets: Resolution of clinical signs (decreased vulvar swelling, reduced pruritus, cessation of undesirable sexual behaviors/aggression, and increased hair regrowth)
- Birds: Decreased egg-laying behavior and physical reproductive activity
- Injection site for signs of pain, irritation, or necrosis
Sobredosis
Because of its high expense and the method of dosing (usually administered by the veterinarian in-clinic), an acute overdose is highly unlikely. Studies in laboratory animals at massive dosages of up to 5 grams/kg IM produced no untoward effects, suggesting a wide margin of safety for acute exposure.
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