In this article, we will discuss Triptorelin (Mechanism of Action). So, let’s get started.
Mechanism of Action
Triptorelin is a synthetic decapeptide agonist analog of gonadotropin releasing hormone (GnRH). Comparative in vitro studies showed that triptorelin was 100-fold more active than native GnRH in stimulating luteinizing hormone release from monolayers of dispersed rat pituitary cells in culture and 20-fold more active than native GnRH in displacing 125I-GnRH from pituitary receptor sites. In animal studies, triptorelin pamoate was found to have 13-fold higher luteinizing hormone-releasing activity and 21-fold higher follicle-stimulating hormone-releasing activity compared to the native GnRH.
Pharmacodynamics
Following the first administration, there is a transient surge in circulating levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and estradiol [see Adverse Reactions (6)]. After chronic and continuous administration, usually 2 to 4 weeks after initiation of therapy, a sustained decrease in LH and FSH secretion and marked reduction of testicular steroidogenesis are observed. A reduction of serum testosterone concentration to a level typically seen in surgically castrated men is obtained. Consequently, the result is that tissues and functions that depend on these hormones for maintenance become quiescent. These effects are usually reversible after cessation of therapy.
Following a single intramuscular injection of TRELSTAR:
- TRELSTAR 3.75 mg: serum testosterone levels first increased, peaking on Day 4, and declined thereafter to low levels by Week 4 in healthy male volunteers.
- TRELSTAR 11.25 mg: serum testosterone levels first increased, peaking on Days 2 – 3, and declined thereafter to low levels by Weeks 3 – 4 in men with advanced prostate cancer.
- TRELSTAR 22.5 mg: serum testosterone levels first increased, peaking on Day 3, and declined thereafter to low levels by Weeks 3 – 4 in men with advanced prostate cancer.