Deslorelin (deslorelin acetate) is a synthetic peptide analogue of gonadotrophin releasing hormone (GnRH). The peptide is made up of nine amino acids and binds to the gonadotropin-releasing hormone receptor . GnRH is the main hormone that controls reproduction in mammals, including humans. On receptor binding, the hormone stimulates the release of of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the brain, which controls many reproductive processes, including oestrogen production and ovulation in the female and testosterone and sperm production in the male . Deslorelin is a super-potent binder of the gonadotropin-releasing hormone receptor and it has been further modified so that it is not degraded . Initial studies have shown that deslorelin is able to induce the release of seven times more LH than naturally occurring GnRH . However, unlike the case of GnRH and GnRH agonists, constant or non-pulsatile activation of the gonadotropin receptors by deslorelin does not inhibit the production of sex hormones . In humans, deslorelin was removed from the body three times slower than GnRH and was found to have a half-life of around 18 minutes . Many animal studies have been carried out using deslorelin and studies in stallions have shown that deslorelin can stimulate the release of LH, FSH and testosterone. These studies concluded that 1.8 mg of deslorelin increased testosterone production by 84% and 3.6 mg of deslorelin increased production by 168% . When continuously used at high doses, deslorelin can also act as a contraceptive and has been shown to cause safe, effective and reversible long-term contraception in male and female cats when administered at 4.6 mg . It is therefore important not to exceed the recommended dose.
Deslorelin is particularly stable in solution and has an estimated shelf life greater than 20 years when stored at 6 °C and at least one year at room temperature . The peptide has been shown to stimulate testosterone production in stallions at 3.6 mg, but also acts as a contraceptive in cats when dosed at 4.6 mg. It is therefore advisable to dose deslorelin by subcutaneous injection at 0.007 mg/kg for testosterone stimulation and never to exceed this dose due to contraceptive effects.
Deslorelin is licensed for use as a veterinary medicine (Suprelorin; Virbac), but the safety profile has not been studied in humans. However, the peptide has been used in many mammals and as a long-term therapy in cats. Even when used as an implant the peptide was considered safe and its effects were found to be reversible .
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