MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
Triptorelin Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
Triptorelin is a synthetic GnRH (LHRH) agonist decapeptide (native GnRH with Gly6 replaced by D-Trp), sold as Trelstar, Decapeptyl, Diphereline and Triptodur. Continuous stimulation first triggers a brief LH/FSH and testosterone surge, then desensitizes the pituitary, producing reversible medical castration (testosterone <50 ng/dL by week 3-4) (PMID 26161143). The flagship use is the prostate-cancer depot: 3.75 mg every 4 weeks, 11.25 mg every 12 weeks, or 22.5 mg every 24 weeks intramuscularly. The immediate-release acetate is dosed at 100 mcg subcutaneously — daily for IVF/ART down-regulation and as a single shot in the diagnostic triptorelin stimulation test (PMID 11432487). The same 100 mcg figure is repurposed for an unproven single-shot PCT protocol. It is FDA-approved (Trelstar 2000; Triptodur 2017) and EMA-approved; research-grade vials are lab-use only and the PCT use is not validated.
Reconstitute: Add 2 mL bacteriostatic water → 1 mg/mL concentration.
Typical dose: 100 mcg SC (single test/daily) or 3.75-22.5 mg IM depot every 4-24 weeks
Easy measuring: At 1 mg/mL, 1 unit = 0.01 mL = 0.0100 mg (10 mcg) on a U-100 insulin syringe.
Storage: Lyophilized vial/powder: store at -20°C for long-term storage, or 2-8°C short term, protected from light. Once reconstituted, keep refrigerated at 2-8°C and use within about 2-4 weeks. Commercial depot kits (Trelstar) are stored per label at controlled room temperature or 2-8°C and reconstituted immediately before injection.
Half-life: Immediate-release ~2.8 h IV (6.6-7.7 h in organ impairment), ~10x longer subcutaneously; depot releases over 4-24 weeks
Route: Clinical depot is intramuscular every 4-24 weeks; immediate-release acetate is 100 mcg subcutaneous (daily or single shot)
Status: FDA-approved — Trelstar (prostate cancer, 2000), Triptodur (precocious puberty, 2017); EMA Decapeptyl. PCT use unproven; research vials lab-use only
About Triptorelin
Triptorelin is a long-acting GnRH (LHRH) agonist decapeptide. Its real-world clinical routes are an intramuscular microsphere depot (Trelstar, Decapeptyl SR) given once every 4 to 24 weeks, and an immediate-release subcutaneous acetate (Decapeptyl 0.1 mg, Gonapeptyl) dosed at 100 mcg [2][10]. The microsphere depot cannot be measured on an insulin syringe, so the subcutaneous reconstitution figures below model the immediate-release 100 mcg regimen used for IVF/ART down-regulation, the diagnostic triptorelin stimulation test, and the off-label single-shot PCT protocol. The depot dosing is described in the text for completeness.\n\nThe Triptorelin dosage spans two very different worlds. For prostate cancer the depot is dosed by total milligrams that release slowly over weeks: 3.75 mg every 4 weeks, 11.25 mg every 12 weeks, or 22.5 mg every 24 weeks, each as one intramuscular injection in the buttock [2][7]. For pituitary down-regulation and diagnostics the immediate-release form is dosed in micrograms: 100 mcg subcutaneously, either once daily (IVF/ART) or as a single shot [5]. A single 100 mcg subcutaneous dose is the basis of the validated triptorelin stimulation test for hypogonadotropic hypogonadism, and it is the same figure repurposed (without trial evidence) for the so-called one-shot PCT.\n\nReconstituting a 2 mg vial with 2 mL of bacteriostatic water yields a 1 mg/mL (1000 mcg/mL) solution, so 100 mcg measures 10 units and 50 mcg measures 5 units on a U-100 insulin syringe.\n\nFrequency: For the immediate-release model below, inject 100 mcg once daily subcutaneously (IVF/ART down-regulation) or as a single subcutaneous shot; clinically the depot is instead a single intramuscular injection every 4 to 24 weeks [2][5].
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 2 mL of bacteriostatic water into a sterile syringe (this yields a 1 mg/mL, i.e. 1000 mcg/mL, solution from a 2 mg vial).
Inject the water slowly down the inner wall of the vial; do not spray directly onto the lyophilized powder and avoid creating foam.
Gently swirl or roll the vial until the solution is fully dissolved and clear — do not shake, as agitation can degrade the peptide.
Load a U-100 insulin syringe to the units for your dose: 100 mcg = 10 units (0.1 mL); 50 mcg = 5 units (0.05 mL).
Swab the injection site (abdomen or thigh), inject subcutaneously, rotate sites between doses, and return the vial to the refrigerator.
Interactive Triptorelin Syringe Calculator
Currently visualizing the 2 mg vial reconstituted with 2 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 2mg dry powder in 2mL water yields 1.00 mg/mL. To evaluate a 250mcg dose, pull to 25.0 units (25 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Triptorelin stimulation test — single diagnostic SC dose | 100 mcg | 10 units (0.10 mL) |
| IVF/ART pituitary down-regulation — once daily SC | 100 mcg | 10 units (0.10 mL) |
| Reduced ART maintenance — once daily SC | 50 mcg | 5 units (0.05 mL) |
| Single-shot PCT (off-label, not clinically validated) | 100 mcg | 10 units (0.10 mL) |
Administration guidelines: Refer to guidelines | 2 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 2 mg vial.
Peptide Vials (Triptorelin, 2 mg each):
- check8 weeks (100 mcg/day, IR model): ~5.6 mg total ≈ 3 vials
- check12 weeks (100 mcg/day): ~8.4 mg total ≈ 5 vials
- check16 weeks (100 mcg/day): ~11.2 mg total ≈ 6 vials
- checkNote: a single-shot stimulation-test/PCT dose (100 mcg) uses only ~5% of one vial
Insulin Syringes (U-100):
- check8 weeks: 56 syringes (1 per daily injection)
- check12 weeks: 84 syringes
- check16 weeks: 112 syringes
Bacteriostatic Water (10 mL bottles): Use 2 mL per vial for reconstitution.
- check8 weeks (3 vials): ~6 mL → 1 × 10 mL bottle
- check12 weeks (5 vials): ~10 mL → 1 × 10 mL bottle
- check16 weeks (6 vials): ~12 mL → 2 × 10 mL bottles
Alcohol Swabs: One for the vial stopper + one for the injection site each day.
- checkPer day: 2 swabs (vial stopper + injection site)
- check8 weeks: ~112 swabs → 1 × 200-count box
- check12 weeks: ~168 swabs → 2 × 100-count boxes
- check16 weeks: ~224 swabs → 3 × 100-count boxes
Mechanism of Action (MOA)
Triptorelin is a superagonist analogue of native gonadotropin-releasing hormone (GnRH, also called LHRH). Native GnRH is the decapeptide pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2; triptorelin substitutes the glycine at position 6 with D-tryptophan. That single D-amino-acid swap blocks the peptidase cleavage that degrades native GnRH within minutes, increases receptor affinity, and raises potency to roughly 100-fold that of the parent hormone [4][9].\n\nThe pharmacology is biphasic. The pituitary gonadotrophs normally respond only to pulsatile GnRH. A first dose of triptorelin acutely stimulates the GnRH receptor, producing a surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and a transient rise in testosterone (men) or estradiol (women) — the clinical flare, which peaks around days 2-4 of depot therapy [2][4]. This acute, measurable LH/FSH/testosterone response is exactly what the diagnostic triptorelin stimulation test exploits: a single 100 mcg subcutaneous dose with LH sampled at ~4 hours and sex steroids at 24 hours distinguishes hypogonadotropic hypogonadism from constitutional delay [5]. With continuous, non-pulsatile exposure from a depot, the receptor desensitizes and down-regulates; Lahlou notes triptorelin suppresses the LH-beta subunit, collapsing bioactive LH output. The result is a profound fall in gonadotropins and sex steroids, reaching castrate testosterone (<50 ng/dL) by week 3-4 and sustained while dosing continues [2][4][7].\n\nPharmacokinetically the immediate-release peptide is short-lived. After a 0.5 mg intravenous bolus in healthy men the terminal half-life is about 2.8 hours, total clearance ~210 mL/min, and elimination occurs by both renal and hepatic routes, with the liver dominant when renal function is impaired; half-life lengthens to roughly 6.6-7.7 hours in renal or hepatic insufficiency [1]. Given subcutaneously, the biological half-life is about 10-fold longer than intravenous because the depot at the injection site releases peptide gradually [4]. The long-acting pamoate (embonate) microsphere formulations extend this further: a single intramuscular dose releases triptorelin over 4 weeks (3.75 mg), 12 weeks (11.25 mg) or 24 weeks (22.5 mg), and because the release kinetics differ the strengths are not interchangeable on a milligram basis [2][7].\n\nDownstream, sustained agonism produces the therapeutic endpoints: medical castration for hormone-sensitive prostate cancer, suppression of endometriotic and fibroid tissue in women, halting of premature puberty in children, and controlled pituitary down-regulation during IVF/ART [2][6]. Effects are reversible — gonadal function typically recovers weeks to months after the last depot clears. This is also why the single-shot 100 mcg PCT idea is mechanistically fragile: one pulse causes a flare (a temporary LH/testosterone bump) rather than the down-regulation seen with chronic dosing, but repeated or higher dosing risks the opposite, paradoxical suppression, and this use has never been validated in a trial [3].
Clinical Trial Efficacy Highlights
- starLebret et al. (Ther Adv Urol 2015) evaluated triptorelin pamoate 11.25 mg given subcutaneously to men with locally advanced or metastatic prostate cancer: 97.5% of patients achieved castrate serum testosterone (<50 ng/dL) by day 29 and 93.0% maintained castration at months 2-12, confirming reliable medical castration with the 3-month formulation [7].
- starAn open-label phase III study of the 6-month formulation (triptorelin embonate 22.5 mg, two intramuscular injections 24 weeks apart) achieved serum testosterone <20 ng/dL in more than 90% of patients on day 169 and day 337, with 98.3% showing absence of LH stimulation after the second injection — establishing durable suppression with biannual dosing [8].
- starThe triptorelin stimulation test (single 100 mcg subcutaneous dose) is a validated diagnostic tool: across pediatric and adult cohorts an LH peak below 4 U/L identifies idiopathic hypogonadotropic hypogonadism with reported sensitivity around 87% and specificity around 96%, and the LH response at 4 hours plus the testosterone response at 24 hours separates hypogonadotropic hypogonadism from constitutional delay of puberty [5].
- starBergqvist et al. (Fertil Steril 1998) randomized 49 women with laparoscopically confirmed endometriosis to triptorelin depot every 4 weeks or placebo for 6 months: triptorelin reduced the pain score by about 50% while placebo pain rose 17%, supporting its approved use in endometriosis [6].
- starMüller et al. (Br J Clin Pharmacol 1997) characterized intravenous triptorelin pharmacokinetics: terminal half-life 2.8 hours in healthy males, total clearance ~210 mL/min, with dual renal and hepatic elimination; half-life rose to 6.6-7.7 hours and clearance fell roughly 2- to 4-fold in renal or hepatic impairment, the basis for caution in organ dysfunction [1].
- starLahlou's pharmacology review (Ann Urol 2005) details the mechanism of sustained suppression: triptorelin preferentially blocks production of the LH-beta subunit, collapsing bioactive LH, while agonist therapy retains efficacy even after a one- to two-day dosing gap — a tolerance advantage over GnRH antagonists [4].
- starA large FAERS pharmacovigilance analysis (Scientific Reports 2025) of real-world triptorelin reports confirms the expected on-target adverse-event signature dominated by hot flushes, hypogonadism-related effects, injection-site reactions and bone/metabolic events, consistent with the controlled-trial safety profile [9].
- starThe FDA Trelstar prescribing information documents that across the 3.75, 11.25 and 22.5 mg formulations testosterone surges initially (peaking days 2-4), then declines to castrate levels by weeks 3-4; transient tumor flare occurred in 5% or fewer of patients and typically resolved within 3-4 weeks [2].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningTumor/clinical flare: the initial testosterone or estradiol surge in the first weeks of depot therapy can transiently worsen disease — in prostate cancer this means a temporary increase in bone pain, urinary obstruction, or rarely spinal cord compression; an anti-androgen is often co-administered to blunt the flare [2].
- warningHot flashes are the most common adverse effect, reported by more than 70% of men on depot therapy, alongside fatigue and sweating [2][8].
- warningHypogonadism effects: erectile dysfunction, decreased libido, testicular atrophy and gynecomastia in men; in women, menopausal-type symptoms, amenorrhea and vaginal dryness reflecting estrogen suppression [2].
- warningLong-term androgen/estrogen deprivation reduces bone mineral density and raises osteoporosis and fracture risk; add-back therapy or bone monitoring is used for prolonged courses [2].
- warningCardiometabolic effects associated with androgen-deprivation therapy include hyperglycemia and new or worsened diabetes, weight gain, dyslipidemia, QT-interval prolongation, and an increased risk of cardiovascular events in predisposed patients [2].
- warningInjection-site reactions, headache, mood changes and depression are reported; rare but serious events include hypersensitivity/anaphylaxis and pituitary apoplexy (sudden headache, visual changes), and the drug is contraindicated in pregnancy [2][9].
- warningResearch/PCT caution: the single 100 mcg subcutaneous shot promoted for post-cycle therapy has never been tested in a controlled trial; one pulse mainly causes a flare, while repeated or higher dosing can drive paradoxical suppression and prolonged hypogonadism — this use is unvalidated and research/educational only [3].
- warningRegulatory status: triptorelin (Trelstar) is FDA-approved (2000) for advanced prostate cancer and Triptodur (2017) for central precocious puberty; Decapeptyl/Diphereline are EMA-approved across Europe. Research-grade lyophilized vials are sold strictly for laboratory use and are not a substitute for a prescribed, pharmaceutical-quality product. This page is educational and is not medical advice.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical Triptorelin dosage?expand_more
It depends entirely on the indication. For advanced prostate cancer the long-acting pamoate depot is dosed as a single intramuscular injection of 3.75 mg every 4 weeks, 11.25 mg every 12 weeks, or 22.5 mg every 24 weeks — these strengths release at different rates and are not interchangeable. The immediate-release acetate is dosed at 100 mcg subcutaneously: once daily for IVF/ART pituitary down-regulation, or as a single shot in the diagnostic triptorelin stimulation test. Central precocious puberty uses the 22.5 mg 6-month depot (Triptodur) or 3.75 mg monthly. The single 100 mcg subcutaneous 'one-shot' dose promoted for post-cycle therapy is off-label and unproven.
Is Triptorelin FDA approved?expand_more
Yes, for specific uses. Trelstar (triptorelin pamoate) received initial FDA approval in 2000 for the palliative treatment of advanced prostate cancer, and Triptodur (triptorelin 22.5 mg, 6-month) was FDA-approved in 2017 for central precocious puberty in children. In Europe, Decapeptyl and Diphereline are EMA-approved across prostate cancer, endometriosis, uterine fibroids, precocious puberty and IVF/ART. However, triptorelin is not FDA-approved for post-cycle therapy or bodybuilding, and research-grade vials are sold for laboratory use only, not as approved pharmaceutical products.
How do you reconstitute Triptorelin and dose it on an insulin syringe?expand_more
For the immediate-release model: draw 2 mL of bacteriostatic water and inject it slowly down the wall of a 2 mg vial to make a 1 mg/mL (1000 mcg/mL) solution. Swirl gently until clear — never shake. On a U-100 insulin syringe, 100 mcg measures 10 units (0.1 mL) and 50 mcg measures 5 units. Store reconstituted solution refrigerated at 2-8°C and use within about 2-4 weeks. Note that the clinical depot (Trelstar, Decapeptyl SR) is a different product — a microsphere suspension reconstituted with its supplied diluent and injected intramuscularly, not measured on an insulin syringe.
What is the half-life of Triptorelin?expand_more
The immediate-release peptide is short-lived: after intravenous dosing in healthy men the terminal half-life is about 2.8 hours, lengthening to roughly 6.6-7.7 hours in renal or hepatic impairment. Given subcutaneously, the effective half-life is about 10 times longer than intravenous because the peptide releases gradually from the injection depot. The long-acting pamoate microsphere formulations extend this dramatically — a single intramuscular injection sustains exposure and testosterone suppression for 4, 12 or 24 weeks depending on the 3.75, 11.25 or 22.5 mg strength.
Can Triptorelin be used for PCT, and is it safe?expand_more
A single 100 mcg subcutaneous shot is promoted in bodybuilding circles to 'restart' the hypothalamic-pituitary-gonadal axis after a steroid cycle, borrowing the dose from the validated triptorelin stimulation test. This PCT use has never been studied in a controlled trial. Mechanistically a single pulse produces a flare (a temporary LH and testosterone rise) rather than lasting recovery, while repeated or higher dosing can cause the opposite — paradoxical pituitary down-regulation, chemical castration and prolonged hypogonadism. Triptorelin is not approved for this purpose; the figures here are educational and not medical advice.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing Triptorelin, plus the universal dosing calculator.
Academic References & Study Citations
Müller FO, Terblanché J, Schall R, et al. (1997) Br J Clin Pharmacol 44(4):335-341. 'Pharmacokinetics of triptorelin after intravenous bolus administration in healthy males and in males with renal or hepatic insufficiency.' Terminal half-life 2.8 h healthy, 6.6-7.7 h in impairment; dual renal/hepatic clearance. View Scientific Paper →
Trelstar (triptorelin pamoate) for injectable suspension — FDA Prescribing Information, DailyMed. Initial U.S. Approval 2000. Dosing (3.75/11.25/22.5 mg IM), testosterone surge/flare, castrate levels, adverse reactions. View Scientific Paper →
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury — Triptorelin. NIH/NCBI Bookshelf (NBK548756). Mechanism, indications, depot forms, FDA approval 2000. View Scientific Paper →
Lahlou N. (2005) Ann Urol (Paris) 39 Suppl 3:S78-84. 'Pharmacokinetics and pharmacodynamics of triptorelin.' LH-beta subunit suppression; sustained-release formulations. View Scientific Paper →
Kauschansky A, Dickerman Z, Phillip M, et al. (2002) A practical GnRH analogue (triptorelin) stimulation test to distinguish constitutional delay of puberty from hypogonadotropic hypogonadism in prepubertal boys. PMID 11432487. View Scientific Paper →
Bergqvist A, Bergh T, Hogström L, et al. (1998) Fertil Steril 69(4):702-708. 'Effects of triptorelin versus placebo on the symptoms of endometriosis.' ~50% pain reduction vs placebo. View Scientific Paper →
Lebret T, Rouanne M, Hublarov O, et al. (2015) Ther Adv Urol 7(3):125-134. 'Efficacy of triptorelin pamoate 11.25 mg administered subcutaneously for achieving medical castration levels of testosterone in prostate cancer.' 97.5% castrate by day 29. View Scientific Paper →
Lundström EA, Rencken RK, van Wyk JH, et al. (2009) Clin Drug Investig. 'Triptorelin 6-month formulation in the management of patients with locally advanced and metastatic prostate cancer: an open-label, phase III study.' Testosterone <20 ng/dL in >90%. View Scientific Paper →
Triptorelin-associated adverse events evaluated using FAERS pharmacovigilance data (2025) Scientific Reports 15. Real-world adverse-event signal analysis. View Scientific Paper →
Triptorelin (Trelstar/Triptodur) Dosage Guide — Drugs.com. Indication-specific dosing for prostate cancer, central precocious puberty and stimulation testing. View Scientific Paper →