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Pharmacotherapeutic group: Gonadotropin releasing hormone analogues. ATC code: L02AE04.
Pharmacology: Pharmacodynamics: Triptorelin (acetate) is a synthetic decapeptide and an analog of the natural hypothalamus hormone GnRH. Triptorelin has a longer duration of action than the natural GnRH and has a biphasic effect at the pituitary level. After an initial large sudden increase in LH and FSH levels (flare-up), circulating LH and FSH levels decrease due to the pituitary GnRH-receptor desensitization, with a consequent marked reduction in the gonadal production. The exact duration of action of DECAPEPTYL 0.1 mg/1 ml has not been established, but pituitary suppression is maintained for at least 6 days after stopping administration. After discontinuation of DECAPEPTYL, a further drop in circulating LH levels should be expected, with LH levels returning to baseline after approximately 2 weeks.
The DECAPEPTYL-induced downregulation of the pituitary can prevent the LH surge and thereby premature ovulation and/or follicular luteinization. The use of the downregulation with GnRH agonist reduces the cycle cancellation rate and improves the pregnancy rate in ART cycles.
Pharmacokinetics: The pharmacokinetic data suggest that after subcutaneous administration of DECAPEPTYL the systemic bioavailability of triptorelin is close to 100%. The elimination half-life of triptorelin is approximately 3-5 hours,
indicating that triptorelin is eliminated within 24 hours and therefore will not be present in circulation at the time of embryo transfer. Metabolism to smaller peptides and amino acids primarily occurs in the liver and kidneys. Triptorelin is predominantly excreted in the urine.
The clinical studies indicated that the risk of accumulation of triptorelin in patients with severe liver and renal impairment is small (i.e. half-life of approximately 8 hours in these patients).
Toxicology: Preclinical safety data: In rats treated over a long period of time with triptorelin, an increase in pituitary tumors has been detected. LHRH analogues are known to induce pituitary tumours in rodents due to the rodent specific regulation of the endocrine system which is different from the regulation in humans. The influence of triptorelin on pituitary abnormalities in humans is unknown and the observation in rats is considered not to be relevant to humans.
Triptorelin is not teratogenic but there are indications for delayed fetal development and parturition in rats.
Preclinical data reveal no special hazard to humans based on repeat dose toxicity and genotoxicity studies.
