Deslorelin: Mechanism, Dosing & Research Data

Deslorelin is a synthetic GnRH superagonist primarily used in veterinary medicine (Suprelorin implant for fertility suppression in dogs and ferrets) and equine reproduction (Ovuplant for LH surge induction). In the research peptide community, deslorelin has been explored for testosterone management and fertility applications in humans, though it lacks FDA approval for human use.

Mechanism of Action

Initial agonist activity: single dose causes GnRHR activation, LH/FSH surge, and transient testosterone/estradiol rise
Continuous release from implant causes complete GnRHR desensitization and down-regulation within 2-4 weeks; castrate-level sex steroids maintained
Suprelorin 4.7 mg (6-month) and 9.4 mg (12-month) implants used in dogs; equivalent testosterone suppression to surgical castration
Ovuplant (2.1 mg deslorelin): single-use implant placed under clitoral fossa or vulva in mares to reliably induce ovulation within 36-42 hours
Human off-label use: implant or compounded SC injection for testosterone suppression in gender-affirming care or fertility preservation

Research Findings

Veterinary (Suprelorin): >95% of treated male dogs achieved testosterone suppression to castrate levels within 6 weeks; behavior modifications comparable to surgical castration
Equine (Ovuplant): 90%+ of mares ovulated within 36-42 hours of deslorelin implant placement; reliable protocol for timed breeding
Human research: small series of deslorelin implants in transgender adolescents showed complete GnRH axis suppression comparable to leuprolide or histrelin
Fertility suppression in ferrets: Suprelorin effectively prevents adrenal disease (a common complication of surgical castration in ferrets) vs surgical approach
Recovery after implant removal: GnRH axis recovery in 2-6 months in humans; testosterone returns to baseline in most cases

Research Protocols

Canine (Suprelorin): single 4.7 mg SC implant for 6-month suppression or 9.4 mg for 12 months; implant between shoulder blades with trocar
Equine (Ovuplant): single 2.1 mg implant under clitoral fossa when dominant follicle >35 mm; ovulation expected at 36-42 hours
Human off-label puberty blockade: 3 mg SC injection monthly or 3.75 mg implant; monitor LH, FSH, estradiol/testosterone
Ferret adrenal disease prevention: 4.7 mg implant SC every 12-18 months; monitor urinary cortisol and adrenal size by ultrasound

Interactions

Anti-androgens (in veterinary or human use): short-term co-administration during first 2 weeks prevents testosterone flare after first implant
Progesterone (equine use): sometimes combined to synchronize estrus before deslorelin-induced ovulation
GnRH antagonists: would block deslorelin receptor binding; contraindicated for concurrent use

Safety Profile

Veterinary approval (Suprelorin, Ovuplant); not FDA-approved for humans. In veterinary use: well-tolerated with expected side effects of chemical castration (weight gain, coat changes, behavior changes). Human off-label use: similar safety to other GnRH agonists. Local implant reactions possible.