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Hormonal · Dosing reference

Triptorelin dosage

Dosing as the FDA label states it, how long trials ran, and the arithmetic for working with vials.

FDA-approvedAHuman trial evidenceFDA label
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Regulatory status
FDA-approved
Human amounts
Prostate cancer (Trelstar): 3.75 mg every 4 weeks, 11.25 mg every 12 weeks or 22.5 mg every 24 weeks. CPP (Triptodur): 22.5 mg every 24 weeks
Route studied
Intramuscular injection
Frequency
Every 4, 12 or 24 weeks depending on formulation
Half-life
Terminal half-life about 3 hours after IV bolus (3-compartment model, healthy men)
Evidence grade
Grade A · Human trial evidence
Vial sizes on the market
Not recorded
Other forms seen
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What Triptorelin is

Triptorelin is a synthetic decapeptide GnRH agonist, FDA-approved (initial U.S. approval 2000) as Trelstar for advanced prostate cancer and as Triptodur for central precocious puberty in children 2 years and older.

Triptorelin is a synthetic decapeptide GnRH agonist 1. Potency In vitro it was 100-fold more active than native GnRH in stimulating LH release from dispersed rat pituitary cells and 20-fold more active in displacing labeled GnRH from pituitary receptors 1. In animals, triptorelin pamoate had 13-fold higher LH-releasing and 21-fold higher FSH-releasing activity than native GnRH 1. Biphasic effect The first dose… How it works →

Key evidence

  • Heyns et al., BJU Int · 2003 · Humans (284 men with advanced prostate cancer)
    Castration at day 29: 91.2% versus 99.3%; at day 57: 97.7% versus 97.1%; cumulative maintenance 96.2% versus 91.2%; 9-month survival 97.0% versus 90.5% 4. 4
  • Trelstar prescribing information, Section 14 (11.25 mg) · 2026 · Humans (346 men with advanced prostate cancer)
    Castration by day 29 in 97.7% and maintained from day 57 through day 253 in 94.4% 1. 1
  • Trelstar prescribing information, Section 14 (22.5 mg) · 2026 · Humans (120 men with advanced prostate cancer)
    Castration by day 29 in 97.5%; maintained from day 57 to day 337 in 93.3% 1. 1
All studies on the research page

Schedules by time period

Label regimens and laid out week by week. Each bar is what the label states or what investigators gave participants; none is a recommendation.

FDA label

Trelstar and Triptodur (FDA labels): dosing 1

Men with advanced prostate cancer; children 2 years and older with CPP

Trelstar 3.75 mg
IM · every 4 weeks
Week-by-week table
PeriodAmount
Weeks 0–onward3.75 mg (maintenance)
Trelstar 11.25 mg
IM · every 12 weeks
Week-by-week table
PeriodAmount
Weeks 0–onward11.25 mg (maintenance)
Trelstar 22.5 mg
IM · every 24 weeks
Week-by-week table
PeriodAmount
Weeks 0–onward22.5 mg (maintenance)
Triptodur 22.5 mg (CPP)
IM · every 24 weeks
Week-by-week table
PeriodAmount
Weeks 0–onward22.5 mg (maintenance)

Cited to the Triptodur label: https://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=f41380e7-b830-432d-a5f5-a872932f107e

Each strength is a separate formulation; they are alternatives, not escalation steps.

Dosing as stated on the FDA label

  • Advanced prostate cancer (Trelstar): a single intramuscular injection of 3.75 mg every 4 weeks, 11.25 mg every 12 weeks, or 22.5 mg every 24 weeks; strengths are not additive and are chosen by desired schedule 1.
  • Central precocious puberty (Triptodur): 22.5 mg as a single intramuscular injection once every 24 weeks, discontinued at the appropriate age for puberty onset 2.
  • Reconstitution and administration instructions are in the labels and are not reproduced here 1,2.

How long did human studies run?

No human study durations are recorded for Triptorelin.

Cycle-length evidence for Triptorelin

Side effects reported in studies

  • Hot flush
    58.6% (82/140) · Men with advanced prostate cancer, Trelstar 3.75 mg 1
  • Skeletal pain
    12.1% · Same trial 1
  • Impotence
    7.1% · Same trial 1
  • Headache
    5.0% · Same trial 1
  • Injection site pain
    45% (children, after injection); 3.6% (men, Trelstar 3.75 mg) · Children with CPP (n=44); men with prostate cancer 2
  • Headache and nasopharyngitis
    13.6% each · Children with CPP (n=44), 12 months 2
Full adverse-event data

Supplies and handling

  • Lyophilized vial
    Sealed vial with the freeze-dried cake. Check the label, lot and the certificate of analysis before opening.
  • Sterile diluent
    The diluent named on the product documentation. Bacteriostatic water contains benzyl alcohol; sterile water does not.
  • Graduated syringes
    Sized to the volume being measured. U-100 insulin syringes are graduated in units where 100 units = 1 mL.
  • Alcohol prep pads
    For wiping vial stoppers before each puncture.
  • Nitrile gloves
    Clean gloves for aseptic handling.
  • Sharps container
    Puncture-resistant container for used needles.
Step-by-step reconstitution guideStorage and transport accessories

Storage

The Trelstar label directs storage at 20-25°C, not frozen 1.

  • Lyophilized (unmixed) vials: typically stored cold and dry, away from light, as the documentation directs. Many are stable longer frozen.
  • Reconstituted vials: typically refrigerated (about 2–8 °C), protected from light and not frozen.
  • Bacteriostatic water contains benzyl alcohol, which inhibits bacterial growth in multi-use vials; sterile water has no preservative.

Handling mistakes and troubleshooting

Added the wrong volume of diluent
The concentration changes, not the amount of compound in the vial. Recalculate with the volume actually added and relabel the vial.
Shook the vial and it foamed
Let it settle in the refrigerator. Foam is a sign of agitation; some peptides aggregate when shaken. Note it on the label.
The solution is cloudy or has particles
Do not use it. Cloudiness can indicate incomplete dissolution, contamination or degradation. Record the lot and contact the supplier with the certificate of analysis.
The powder cake looks melted or shrunken before reconstitution
This can indicate the vial was exposed to heat or moisture. Record the lot and condition on arrival.
Liquid sprayed back when the needle was removed
Pressure built up in the vial. Withdraw a small volume of air while adding diluent to keep pressure neutral.

Regulatory status

Status
FDA-approved (initial U.S. approval 2000). As of 2026-10-24 Drugs@FDA lists Trelstar 3.75 mg, 11.25 mg and 22.5 mg and Triptodur 22.5 mg with prescription marketing status 1,2,3.
United States (FDA)
FDA-approved (initial U.S. approval 2000): Trelstar (NDA 020715, 021288, 022437) and Triptodur (NDA 208956), all listed with prescription marketing status as of 2026-10-24 1,2,3.
Sport (WADA)
The WADA 2026 Prohibited List names triptorelin among GnRH agonist analogues under S2.2.1 (testosterone-stimulating peptides in males); S2 is prohibited at all times 5.

Status varies by country and changes over time. How we describe regulatory status.

Triptorelin compared with related compounds

CompoundStatusEvidenceHuman amountsHalf-life
TriptorelinFDA-approvedAFDA labelTerminal half-life about 3 hours after I
LeuprolideFDA-approvedAFDA labelApproximately 3 hours (elimination, two-
GonadorelinApproved, no longer marketedBLabel not retrievableA review describes native GnRH as having
Kisspeptin-54Not approved — research use onlyBNone establishedAbout 28 minutes (intravenous, healthy m
Apelin-13Not approved — research use onlyBNone establishedNot located as a numeric value in the so
hCG (human chorionic gonadotropin)FDA-approvedAFDA labelAbout 29 hours (recombinant hCG, subcuta

Frequently asked questions

What doses of Triptorelin have been studied in humans?
Triptorelin is FDA-approved, so the label states the dosing for the approved product. This page quotes it, with citations. It does not apply to research-grade material.
Is there an established Triptorelin cycle length?
No. We found no human studies that report treatment duration for Triptorelin.
How much bacteriostatic water should be added to a Triptorelin vial?
There is no compound-specific volume. The diluent volume only sets the concentration: concentration = mass in the vial ÷ volume added (for example, 10 mg in 2 mL gives 5 mg/mL). The calculator on this page shows the arithmetic for any combination.
How many units is a given amount on an insulin syringe?
On a U-100 syringe, 100 units = 1 mL. Units for an amount = amount ÷ (concentration per unit). The calculator converts any amount you enter at the concentration you choose; a unit is a volume mark, not an amount of compound.
What is the half-life of Triptorelin?
Terminal half-life about 3 hours after IV bolus (3-compartment model, healthy men)
Is Triptorelin FDA-approved?
FDA-approved. FDA-approved (initial U.S. approval 2000). As of 2026-10-24 Drugs@FDA lists Trelstar 3.75 mg, 11.25 mg and 22.5 mg and Triptodur 22.5 mg with prescription marketing status 1,2,3.

References

  1. TRELSTAR (triptorelin pamoate for injectable suspension) prescribing information (DailyMed, effective 06/2026) FDA label (DailyMed). 2026
  2. TRIPTODUR (triptorelin) for extended-release injectable suspension prescribing information (DailyMed, effective 09/2025) FDA label (DailyMed). 2025
  3. Drugs@FDA (openFDA) application records for triptorelin (NDA 020715, 021288, 022437, 208956) U.S. FDA. 2026
  4. Comparative efficacy of triptorelin pamoate and leuprolide acetate in men with advanced prostate cancer BJU Int. 2003
  5. World Anti-Doping Agency Prohibited List 2026 (online version) WADA. 2026
  6. PubChem compound record for triptorelin PubChem. 2026

Last reviewed October 24, 2026 by the Amiravo editorial team. Editorial policy · Report an error