Triptorelin: uses and Pharmacokinetics

Description

Triptorelin is a gonadorelin analogue (also known as a luteinising hormone-releasing hormone (LHRH) analogue) available as a 4-weekly, 3-monthly and 6-monthly intramuscular (I/M) injection[1].

Triptorelin is administered to patients in the form of acetate or pamoate (also known as embonate) salts. In response to the need for ADT regimens that improve convenience and treatment adherence, sustained-release 1-month (3 or 3.75 mg), 3-month (11.25 mg), and 6-month (22.5 mg) formulations of triptorelin have been developed. Sustained-release formulations of triptorelin comprise microparticles of the decapeptide incorporated within a biocompatible and biodegradable copolymer (polylactide-co-glycolide).

Uses

Triptorelin is used to treat advanced prostate cancer. It is a hormone similar to the one normally released from the hypothalamus gland in the brain. When given on a regular basis to men, triptorelin decreases testosterone levels, which helps treat prostate cancer.

Pharmacokinetics

Following intravenous bolus administration, triptorelin is distributed and eliminated by hepatic and renal routes according to a three-compartment model that corresponds to plasma half-lives of 6 min, 45 min, and 3 h. Sustained-release intramuscular (IM) administration of triptorelin initially stimulates LH and FSH secretion, with the subsequent production of testosterone. Bioequivalence studies suggest a maximal increase in testosterone at around 4 days post-triptorelin administration. Testosterone levels progressively decline after this initial increase with continuous exposure to triptorelin[2].

Triptorelin is usually administered by IM injection. After the first month, mean serum levels of triptorelin are stable at 0.06 ng/ml for approximately 12 weeks after a single IM injection of a triptorelin pamoate 3-month formulation, with mean (standard deviation) C max of 35.7 ng/ml (18.3 ng/ml) and C min of 0.063 ng/ml (range 0.021–0.174 ng/ml). A single IM administration of the 6-month formulation of triptorelin pamoate produced a C max of 40.0 ng/ml (range 22.2–76.8 ng/ml).

Side effects

High blood pressure, which may cause blurred vision;

Swelling of arms legs;

Blockage of the airway, which may cause cough;

Infection which may cause frequent urination, pain or difficulty emptying the bladder or urinating;

Diabetes;

Nausea, vomiting, constipation;

Pain in the belly which may cause diarrhoea;

Breast tenderness or swelling;

Decrease of sexual ability or desire, shrinkage of the testis;

Pain including in bones and joints;

Numbness, pain, and tingling of the arms, legs, fingers, and/or toes;

Difficulty sleeping, depression, changes in mood, etc.

References

[1] Axel S. Merseburger, Marie C. Hupe. “An Update on Triptorelin: Current Thinking on Androgen Deprivation Therapy for Prostate Cancer.” Advances in Therapy 33 7 (2016): 1072–1093.

[2] Triptorelin - LiverTox - NCBI Bookshelf (nih.gov). https://www.ncbi.nlm.nih.gov/books/NBK548756/#:~:text= Triptorelin%20is%20a%20gonadotropin%20releasing,to%20treat%20advanced%20prostate%20cancer.