Short answer: Triptorelin has a half-life of about 3 hours (after an IV dose). Levels peak 1 to 3 hours after a Trelstar injection after a dose. People vary, so treat these as estimates.
Triptorelin is a synthetic version of gonadotropin-releasing hormone (GnRH), the brain hormone that tells the pituitary to release LH and FSH. Given long term it shuts that signal down and lowers testosterone. It is FDA approved as Trelstar for advanced prostate cancer and as Triptodur for early (central precocious) puberty in children.
Also known as: Trelstar, Triptodur.
Trelstar comes as single-dose kits of 3.75 mg (one injection every 4 weeks), 11.25 mg (every 12 weeks) and 22.5 mg (every 24 weeks), each mixed with the sterile water in the kit and injected into the buttock muscle all at once. The label says the strengths are not additive, so two smaller kits do not equal a larger one. Triptodur is a 22.5 mg kit given into muscle every 24 weeks. There is nothing to measure: each kit is one whole dose, given by a healthcare provider.
The Trelstar label approves triptorelin for advanced prostate cancer, given as one injection into muscle every 4, 12 or 24 weeks depending on the strength, under a physician's supervision. The Triptodur label approves it for children 2 years and older with central precocious puberty, as 22.5 mg every 24 weeks given by a healthcare provider.
The labels warn that triptorelin first causes a short rise in testosterone (Trelstar) or in puberty hormones (Triptodur) before levels fall; in prostate cancer this flare can briefly worsen symptoms. Trelstar's warnings also include serious allergic reactions, metabolic changes (high blood sugar, diabetes and high blood fats), a higher reported risk of heart attack, sudden cardiac death and stroke in men, seizures, severe skin reactions, QT prolongation, and harm to an unborn baby.
WADA bans GnRH agonists, naming triptorelin, as testosterone-stimulating peptides in males (S2.2.1), in and out of competition.
The Trelstar label says that after an IV dose in healthy men, triptorelin has half-lives of about 6 minutes, 45 minutes and 3 hours (a 3-compartment model; 2.81 hours in its table), and that after one Trelstar injection into muscle, peak levels came 1 to 3 hours later. The kits are long-acting: the drug keeps releasing for weeks, which is why one injection lasts 4, 12 or 24 weeks. Kidney or liver problems raised exposure 2- to 4-fold.
Numbers shown are taken from the source above. Half-life varies from person to person.
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