Evidence Grade A — Regulatory approved. 994 published studies. 40 registered clinical trials.
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Triptorelin (sold as Trelstar) is a hormone-suppressing injectable for advanced prostate cancer, available in one-month, three-month, and six-month depot formulations. It is one of the most commonly used GnRH agonists worldwide and has also been widely used internationally as a puberty blocker in gender-affirming care and central precocious puberty.
Triptorelin is also known by these brand and alternate names:
994 published studies: 747 human, 79 animal, 133 in-vitro, 76 reviews
Triptorelin is marketed as Trelstar (approved 2000) for advanced prostate cancer, available as intramuscular depot injections in monthly (3.75 mg), three-monthly (11.25 mg), and six-monthly (22.5 mg) formulations. It is also widely used internationally for gender-affirming care and central precocious puberty.
Triptorelin is one of the most commonly used GnRH agonists globally, though it faces the same competitive pressure as other agents in this class from newer oral GnRH antagonists like relugolix, which avoid the initial hormone flare and offer potential cardiovascular advantages. Clinical data demonstrate reliable testosterone suppression comparable to other GnRH agonists in this class.
Triptorelin works through the standard GnRH agonist mechanism: continuous stimulation of the pituitary gland causes an initial brief hormone surge followed by sustained shutdown of sex hormone production. It achieves castrate-level testosterone suppression in over 90% of patients within the first month. The depot injection forms a slow-release reservoir at the injection site, maintaining therapeutic drug levels for one to six months depending on the formulation.
Triptorelin's evidence base is well established, with reliable testosterone suppression comparable to other GnRH agonists in the class. The six-month formulation offers the longest dosing interval among injectable GnRH agonists, reducing clinic visits to just twice yearly. Like all GnRH agonists, triptorelin causes an initial testosterone surge before suppression takes effect, and long-term hormone suppression carries risks of bone density loss, cardiovascular effects, and metabolic changes. The oral GnRH antagonist relugolix (Orgovyx) has emerged as a competitor that avoids the initial hormone surge and offers potential cardiovascular advantages. Triptorelin's use in gender-affirming care for adolescents has been a focus of both clinical research and regulatory discussion across multiple countries.
PeptideTrace tracks 40 registered clinical trials for Triptorelin sourced from ClinicalTrials.gov.
Triggering Oocyte Maturation in POSEIDON Group 3 and 4 Poor Responders Using Double Trigger or HCG Trigger
Triggering Ovulation in Normo-responders Using a Modified Dual Trigger Protocol or HCG Trigger
Efficacy, Safety, and Pharmacokinetics of FP-014, 11.25 mg in Patients With Advanced Prostate Cancer
Efficacy, Safety, and Pharmacokinetics of FP-014, 22.5 mg in Patients With Advanced Prostate Cancer
A Study to Assess the Efficacy, Safety, and Pharmacokinetics of Debio 4326 in Pediatric Participants With Central Precocious Puberty (LIBELULA™ Clinical Trial)
FDA ORIG 1
FDA SUPPL 1
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FDA ORIG 1
FDA SUPPL 4
FDA SUPPL 3
FDA SUPPL 6
FDA SUPPL 2
Health Canada Market Authorisation
FDA SUPPL 13
FDA SUPPL 9
FDA SUPPL 16
FDA SUPPL 13
FDA ORIG 1
FDA SUPPL 18
FDA SUPPL 15
FDA SUPPL 24
FDA SUPPL 21
FDA SUPPL 2
FDA SUPPL 25
FDA SUPPL 22
FDA SUPPL 3
FDA SUPPL 30
FDA SUPPL 27
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FDA SUPPL 28
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FDA SUPPL 6
FDA SUPPL 27
FDA SUPPL 24
FDA SUPPL 4
FDA SUPPL 29
FDA SUPPL 31
FDA SUPPL 9
FDA SUPPL 32
FDA SUPPL 28
FDA SUPPL 8
FDA SUPPL 33
FDA SUPPL 29
FDA SUPPL 10
FDA SUPPL 11
FDA SUPPL 34
FDA ORIG 1
FDA SUPPL 40
FDA SUPPL 35
FDA SUPPL 15
FDA SUPPL 2
FDA SUPPL 10
FDA SUPPL 9
FDA SUPPL 45
FDA SUPPL 40
FDA SUPPL 20
FDA SUPPL 47
FDA SUPPL 42
FDA SUPPL 22
FDA SUPPL 49
FDA SUPPL 44
FDA SUPPL 24
FDA SUPPL 50
FDA SUPPL 45
FDA SUPPL 25
FDA SUPPL 51
FDA SUPPL 14
FDA SUPPL 46
FDA SUPPL 26
Triptorelin is a synthetic decapeptide (10 amino acids) GnRH agonist with a D-Trp6 substitution, conferring approximately 100-fold greater potency than native GnRH. It is available in multiple intramuscular depot formulations.
Triptorelin shares the GnRH agonist mechanism: continuous stimulation → initial flare → receptor downregulation → sustained sex steroid suppression. Castrate testosterone levels are achieved by day 29 in 91–98% of patients across formulations. The D-Trp6 modification provides high receptor affinity and metabolic stability.
Triptorelin is marketed as Trelstar (approved June 15, 2000). Available as IM depot formulations: 3.75 mg monthly, 11.25 mg 3-monthly, and 22.5 mg 6-monthly. The primary indication is advanced prostate cancer. Triptorelin is also widely used internationally for gender-affirming care as a puberty blocker.
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Carbetocin has not been approved by the FDA. It is registered in over 80 countries for prevention of uterine atony and excessive bleeding after caesarean delivery. A heat-stable formulation was added to the WHO Essential Medicines List in 2019. The CHAMPION trial (WHO, 2018; over 29,000 women) compared a heat-stable carbetocin formulation to oxytocin for preventing postpartum haemorrhage after vaginal delivery, and found it to be non-inferior. The heat-stable formulation addresses a significant limitation of oxytocin, which degrades in warm climates without refrigeration — a major concern in low-resource settings where postpartum haemorrhage causes the most deaths. Its regulatory status varies by jurisdiction.
Nafarelin is marketed as Synarel (approved 1990) for endometriosis and central precocious puberty. It requires administration as one spray in each nostril twice daily — a higher frequency than injectable alternatives but avoids needles entirely, which can be a significant advantage for some patients, particularly children. Clinical trials showed symptom improvement in 75–92% of endometriosis patients. However, absorption can be affected by nasal congestion or concurrent use of nasal decongestants, which can be a practical limitation. As with all GnRH agonists, prolonged use leads to bone density loss, and treatment for endometriosis is typically limited to six months. Nafarelin occupies a niche for patients who prefer non-injectable hormone suppression, though it has become less commonly prescribed as longer-acting depot injections and oral alternatives have become available.
Histrelin is available as Supprelin LA for central precocious puberty (approved 2007). The Vantas implant for prostate cancer was approved in 2004 but discontinued in 2021. The implant requires a minor surgical procedure for insertion and removal/replacement each year. Supprelin LA's main clinical advantage is its 12-month duration — the longest of any GnRH agonist — which is particularly valuable in paediatric patients where treatment compliance over years is important. Clinical studies demonstrated effective suppression of puberty markers in over 97% of patients. The implant has also seen significant off-label use in gender-affirming care as a puberty blocker, where its annual dosing schedule offers practical benefits for adolescent patients and their families.
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