Mechanism

How it works

Triptorelin binds with high affinity to GnRH receptors on anterior pituitary gonadotrophs; a single low dose produces a brief 'flare' effect—stimulating LH and FSH release—which can serve as a diagnostic or restorative signal to the HPG axis. With repeated or continuous dosing, receptor downregulation and pituitary desensitization lead to profound suppression of LH, FSH, and consequently gonadal testosterone and estrogen synthesis. The paradox of agonist-induced suppression makes dosing strategy critical: a single very low dose (100–500 mcg) is hypothesized to 'reset' a suppressed axis, whereas chronic high-dose use results in medical castration.

Reported in research

Benefits

Potential single-dose HPG axis 'reset' for post-cycle hypogonadism recovery (research context)
Clinically proven suppression of testosterone in prostate cancer management
Effective treatment of endometriosis and uterine fibroids via estrogen suppression
Used in central precocious puberty to halt premature gonadotropin secretion

Context, not a prescription

Dosing

Typical range: 100 mcg single dose (off-label HPG reset) | 3.75 mg monthly depot (clinical oncology/endocrinology) (Subcutaneous, Intramuscular)
Cycle length: Single dose for HPG reset; 3–6 months for clinical indications; ongoing for prostate cancer
Half-life: ~7–8 hours (aqueous); depot formulations release over 1–3 months

Safety

Side effects & contraindications

Possible side effects

Hot flashes and night sweats due to estrogen/testosterone suppression
Decreased libido and sexual dysfunction
Transient testosterone/estrogen flare upon first injection
Bone mineral density loss with prolonged use
Mood changes, depression, and fatigue
Injection site reactions (pain, erythema, swelling)
Headache and dizziness
Nausea

Contraindications

Pregnancy or breastfeeding (teratogenic risk)
Known hypersensitivity to GnRH analogues or any excipient
Hormone-sensitive conditions where estrogen/testosterone flare is dangerous (e.g., spinal metastases — flare risk)
Undiagnosed vaginal bleeding
Pediatric use outside of supervised central precocious puberty treatment

Research information, not medical advice. Always consult a licensed clinician before considering any peptide.

In depth

Full profile

What it does

Users may notice early signs of testosterone recovery such as improved mood, early morning erections, and increased energy within the first 1–2 weeks if used for HPG axis recovery. If used at clinical suppressive doses, the opposite occurs: libido decreases, fatigue sets in, and hot flashes may develop.

How it works

Think of your body's hormone system like a thermostat and a furnace. GnRH is the signal that tells the furnace to fire. A single tap on the thermostat (low single dose) briefly kicks the furnace back on after it's been idle. But if you hold the thermostat button down continuously, the furnace eventually gives up responding and switches off entirely.

After a single low-dose injection under the skin or into muscle, triptorelin briefly stimulates your pituitary gland to release LH and FSH—the hormones that tell your testes or ovaries to produce testosterone or estrogen. This brief surge can help 're-prime' a suppressed hormonal axis, for example after a course of anabolic steroids. The body begins responding within hours, with peak hormone effects seen at 4–8 hours post-injection.

What to expect

Hormonal flare (LH/FSH surge) begins within 2–4 hours of injection; peak at approximately 4–8 hours. Effects on testosterone levels may be measurable within 24 hours.

Hours 2–8: Rapid LH and FSH surge ('flare effect') following injection; potential early signs of hormonal stimulation
Days 2–7: Testosterone levels may begin rising if HPG axis was suppressed; mood and energy may start to improve
Weeks 2–4: If the axis has responded, testosterone continues to normalize. Follow-up bloodwork recommended to confirm recovery

Good to know

Never use this compound without lab-confirmed hypogonadism and physician oversight
Start with the lowest effective research dose (e.g., 100 mcg) to minimize flare risk
Have baseline and follow-up hormone panels (LH, FSH, Total Testosterone, Estradiol) before and after use
Never combine with other GnRH analogues or androgens without professional guidance

Staying safe

Hot flashes and sweating, especially at higher doses
Temporary soreness or redness at the injection site
Mood fluctuations or low energy during the hormonal adjustment period
Temporary increase in symptoms if hormone-sensitive conditions are present (flare)

Avoid if you have:

Women who are pregnant or trying to become pregnant
Anyone with hormone-sensitive cancers without physician supervision
People with a history of allergic reactions to GnRH drugs
Children, except under strict medical supervision for precocious puberty

Overview

Acutely: LH may rise 5–10× above baseline; FSH rises 2–4×; testosterone surges 1.5–3× above baseline within 72 hours. With chronic dosing: testosterone falls to castrate levels (<50 ng/dL) within 3–4 weeks. Bone mineral density losses of 2–5% annually are documented with long-term medical castration. Transient PSA flare is documented in prostate cancer patients during the initial surge phase.

How it works

GnRHR signaling is analogous to a pulsatile Morse code signal: normal physiology requires intermittent, pulsatile GnRH input (approximately every 90–120 minutes) to maintain pituitary responsiveness. Triptorelin's high receptor affinity and metabolic stability convert this pulsatile code into a continuous tone, which initially rings alarm bells (flare) but rapidly causes the receiver (pituitary) to go deaf (downregulation). A single brief transmission at low power replicates one natural pulse without inducing receptor desensitization.

Triptorelin is absorbed rapidly after subcutaneous or intramuscular injection with a Tmax of approximately 1–3 hours (aqueous formulation). It binds extensively to pituitary GnRHRs with a Kd in the low nanomolar range. The LH surge peaks at 4–8 hours post-injection; FSH peaks slightly later (~6–10 hours). Downstream testosterone surge in males peaks at 24–72 hours. The aqueous half-life is ~7–8 hours; depot (microsphere) formulations achieve sustained plasma levels over 1 or 3 months. Metabolism occurs via peptidase cleavage; renal elimination of metabolites. Bioavailability via SC/IM routes is ~97%.

Onset & timeline

Plasma triptorelin detectable within 15–30 minutes post-injection. LH surge begins at 2–4 hours; testosterone flare in 24–72 hours. Desensitization and gonadotropin suppression (with repeated dosing) becomes evident by 2–4 weeks of continuous administration.

Hours 0–8: Rapid GnRHR binding initiates Gαq/11-PLC-β-IP3-Ca2+ signaling cascade. LH and FSH secreted in large, non-pulsatile bolus. Peak plasma LH at approximately 4–6 hours post-injection.
Days 1–3: Testosterone flare in males: serum levels rise to supranormal or high-normal range. In HPG-suppressed individuals, this represents functional axis response confirmation. PSA flare possible in prostate cancer patients.
Weeks 1–4 (single dose): Hormonal axis returns toward new baseline. In hypogonadal individuals, LH and FSH pulsatility may begin recovering. Testosterone normalization trajectory depends on pre-existing Leydig cell reserve.
Weeks 2–12 (chronic dosing): Progressive GnRHR downregulation leads to gonadotropin suppression; testosterone falls to castrate levels by week 3–4. Full suppression (testosterone <50 ng/dL) maintained with monthly or quarterly depot injections.

Getting the most from it

In prostate cancer, co-administer a non-steroidal antiandrogen (e.g., bicalutamide) for 2–4 weeks before and after first triptorelin injection to attenuate testosterone flare
Monitor bone mineral density annually with DEXA scan; supplement calcium and vitamin D; consider bisphosphonate co-therapy for long-term use
Baseline and quarterly ECG monitoring for QTc prolongation during androgen deprivation therapy
For off-label HPG reset: confirm pre-injection hypogonadism via serum LH, FSH, total testosterone, and prolactin; recheck at 4–6 weeks post-injection to assess response

Common side effects

Vasomotor hot flashes (up to 80% incidence with chronic use) — mediated by hypothalamic thermoregulatory disruption from estrogen withdrawal
Hypogonadal symptoms: decreased libido, erectile dysfunction, fatigue, sarcopenia — direct consequence of testosterone suppression
Initial disease flare in prostate cancer: PSA and bone pain can worsen transiently in first 1–2 weeks due to testosterone surge
Injection site reactions: local pain, induration, sterile abscess (rare with proper technique)

Mechanism of action

Triptorelin is a synthetic D-Trp6 analogue of native GnRH (also called LHRH), where substitution of L-glycine at position 6 with D-tryptophan confers resistance to enzymatic degradation and increased GnRH receptor binding affinity (~100× that of native GnRH). Upon binding to pituitary GnRH receptors (GnRHR, a Gαq/11-coupled GPCR), it activates phospholipase C-β, generating IP3 and DAG, which mobilize intracellular Ca2+ and activate PKC — ultimately triggering LH and FSH exocytosis. With continuous or repeated dosing, receptor internalization, uncoupling from G-proteins, and downregulation of GnRHR expression lead to complete pituitary desensitization, abolishing gonadotropin pulsatility. A single low dose (<500 mcg) avoids sustained receptor occupancy, allowing the transient LH/FSH flare without progressing to desensitization — the theoretical basis for the 'single-dose HPG reset' approach.

Triptorelin is absorbed rapidly after subcutaneous or intramuscular injection with a Tmax of approximately 1–3 hours (aqueous formulation). It binds extensively to pituitary GnRHRs with a Kd in the low nanomolar range. The LH surge peaks at 4–8 hours post-injection; FSH peaks slightly later (~6–10 hours). Downstream testosterone surge in males peaks at 24–72 hours. The aqueous half-life is ~7–8 hours; depot (microsphere) formulations achieve sustained plasma levels over 1 or 3 months. Metabolism occurs via peptidase cleavage; renal elimination of metabolites. Bioavailability via SC/IM routes is ~97%.

Pharmacodynamics

Plasma triptorelin detectable within 15–30 minutes post-injection. LH surge begins at 2–4 hours; testosterone flare in 24–72 hours. Desensitization and gonadotropin suppression (with repeated dosing) becomes evident by 2–4 weeks of continuous administration.

Acutely: LH may rise 5–10× above baseline; FSH rises 2–4×; testosterone surges 1.5–3× above baseline within 72 hours. With chronic dosing: testosterone falls to castrate levels (<50 ng/dL) within 3–4 weeks. Bone mineral density losses of 2–5% annually are documented with long-term medical castration. Transient PSA flare is documented in prostate cancer patients during the initial surge phase.

Timeline

Hours 0–8: Rapid GnRHR binding initiates Gαq/11-PLC-β-IP3-Ca2+ signaling cascade. LH and FSH secreted in large, non-pulsatile bolus. Peak plasma LH at approximately 4–6 hours post-injection.
Days 1–3: Testosterone flare in males: serum levels rise to supranormal or high-normal range. In HPG-suppressed individuals, this represents functional axis response confirmation. PSA flare possible in prostate cancer patients.
Weeks 1–4 (single dose): Hormonal axis returns toward new baseline. In hypogonadal individuals, LH and FSH pulsatility may begin recovering. Testosterone normalization trajectory depends on pre-existing Leydig cell reserve.
Weeks 2–12 (chronic dosing): Progressive GnRHR downregulation leads to gonadotropin suppression; testosterone falls to castrate levels by week 3–4. Full suppression (testosterone <50 ng/dL) maintained with monthly or quarterly depot injections.

Comparisons

Triptorelin Acetate — effectiveness Very High, safety Caution, cost $$, Medium to use
Leuprolide Acetate — effectiveness Very High, safety Caution, cost $$$, Medium to use
Gonadorelin (native GnRH) — effectiveness High, safety Moderate, cost $$, Medium to use
hCG (human Chorionic Gonadotropin) — effectiveness High, safety Good, cost $$, Medium to use

Adverse effects

Common:

Vasomotor hot flashes (up to 80% incidence with chronic use) — mediated by hypothalamic thermoregulatory disruption from estrogen withdrawal
Hypogonadal symptoms: decreased libido, erectile dysfunction, fatigue, sarcopenia — direct consequence of testosterone suppression
Initial disease flare in prostate cancer: PSA and bone pain can worsen transiently in first 1–2 weeks due to testosterone surge
Injection site reactions: local pain, induration, sterile abscess (rare with proper technique)

Rare:

Anaphylactic/anaphylactoid reactions (<0.1% incidence): urticaria, bronchospasm, hypotension — GnRH receptor-mediated or excipient hypersensitivity
QT interval prolongation with chronic androgen deprivation therapy — associated with cardiovascular mortality risk
Pituitary apoplexy (extremely rare): hemorrhage or infarction in existing pituitary adenoma triggered by GnRH flare
Spinal cord compression in prostate cancer metastases due to initial testosterone flare (<1%)

Contraindications & risk mitigation

Contraindicated in:

Patients with hormone-sensitive prostate cancer and vertebral metastases (flare may precipitate spinal cord compression; antiandrogen flare protection required)
Women with undiagnosed abnormal uterine bleeding or suspected estrogen-dependent malignancy
Individuals with known pituitary adenoma (risk of apoplexy)
Patients on QT-prolonging medications (additive cardiac risk via androgen deprivation)
Individuals with osteoporosis or significant bone mineral density deficit (accelerated bone loss)

In prostate cancer, co-administer a non-steroidal antiandrogen (e.g., bicalutamide) for 2–4 weeks before and after first triptorelin injection to attenuate testosterone flare
Monitor bone mineral density annually with DEXA scan; supplement calcium and vitamin D; consider bisphosphonate co-therapy for long-term use
Baseline and quarterly ECG monitoring for QTc prolongation during androgen deprivation therapy
For off-label HPG reset: confirm pre-injection hypogonadism via serum LH, FSH, total testosterone, and prolactin; recheck at 4–6 weeks post-injection to assess response

Qué hace

Users may notice early signs of testosterone recovery such as improved mood, early morning erections, and increased energy within the first 1–2 weeks if used for HPG axis recovery. If used at clinical suppressive doses, the opposite occurs: libido decreases, fatigue sets in, and hot flashes may develop.

Cómo funciona

Think of your body's hormone system like a thermostat and a furnace. GnRH is the signal that tells the furnace to fire. A single tap on the thermostat (low single dose) briefly kicks the furnace back on after it's been idle. But if you hold the thermostat button down continuously, the furnace eventually gives up responding and switches off entirely.

After a single low-dose injection under the skin or into muscle, triptorelin briefly stimulates your pituitary gland to release LH and FSH—the hormones that tell your testes or ovaries to produce testosterone or estrogen. This brief surge can help 're-prime' a suppressed hormonal axis, for example after a course of anabolic steroids. The body begins responding within hours, with peak hormone effects seen at 4–8 hours post-injection.

Qué esperar

Hormonal flare (LH/FSH surge) begins within 2–4 hours of injection; peak at approximately 4–8 hours. Effects on testosterone levels may be measurable within 24 hours.

Hours 2–8: Rapid LH and FSH surge ('flare effect') following injection; potential early signs of hormonal stimulation
Days 2–7: Testosterone levels may begin rising if HPG axis was suppressed; mood and energy may start to improve
Weeks 2–4: If the axis has responded, testosterone continues to normalize. Follow-up bloodwork recommended to confirm recovery

Bueno saber

Never use this compound without lab-confirmed hypogonadism and physician oversight
Start with the lowest effective research dose (e.g., 100 mcg) to minimize flare risk
Have baseline and follow-up hormone panels (LH, FSH, Total Testosterone, Estradiol) before and after use
Never combine with other GnRH analogues or androgens without professional guidance

Manteniéndose seguro

Hot flashes and sweating, especially at higher doses
Temporary soreness or redness at the injection site
Mood fluctuations or low energy during the hormonal adjustment period
Temporary increase in symptoms if hormone-sensitive conditions are present (flare)

Evitar si tienes:

Women who are pregnant or trying to become pregnant
Anyone with hormone-sensitive cancers without physician supervision
People with a history of allergic reactions to GnRH drugs
Children, except under strict medical supervision for precocious puberty

Descripción general

Acutely: LH may rise 5–10× above baseline; FSH rises 2–4×; testosterone surges 1.5–3× above baseline within 72 hours. With chronic dosing: testosterone falls to castrate levels (<50 ng/dL) within 3–4 weeks. Bone mineral density losses of 2–5% annually are documented with long-term medical castration. Transient PSA flare is documented in prostate cancer patients during the initial surge phase.

Cómo funciona

GnRHR signaling is analogous to a pulsatile Morse code signal: normal physiology requires intermittent, pulsatile GnRH input (approximately every 90–120 minutes) to maintain pituitary responsiveness. Triptorelin's high receptor affinity and metabolic stability convert this pulsatile code into a continuous tone, which initially rings alarm bells (flare) but rapidly causes the receiver (pituitary) to go deaf (downregulation). A single brief transmission at low power replicates one natural pulse without inducing receptor desensitization.

Triptorelin is absorbed rapidly after subcutaneous or intramuscular injection with a Tmax of approximately 1–3 hours (aqueous formulation). It binds extensively to pituitary GnRHRs with a Kd in the low nanomolar range. The LH surge peaks at 4–8 hours post-injection; FSH peaks slightly later (~6–10 hours). Downstream testosterone surge in males peaks at 24–72 hours. The aqueous half-life is ~7–8 hours; depot (microsphere) formulations achieve sustained plasma levels over 1 or 3 months. Metabolism occurs via peptidase cleavage; renal elimination of metabolites. Bioavailability via SC/IM routes is ~97%.

Inicio y cronología

Plasma triptorelin detectable within 15–30 minutes post-injection. LH surge begins at 2–4 hours; testosterone flare in 24–72 hours. Desensitization and gonadotropin suppression (with repeated dosing) becomes evident by 2–4 weeks of continuous administration.

Hours 0–8: Rapid GnRHR binding initiates Gαq/11-PLC-β-IP3-Ca2+ signaling cascade. LH and FSH secreted in large, non-pulsatile bolus. Peak plasma LH at approximately 4–6 hours post-injection.
Days 1–3: Testosterone flare in males: serum levels rise to supranormal or high-normal range. In HPG-suppressed individuals, this represents functional axis response confirmation. PSA flare possible in prostate cancer patients.
Weeks 1–4 (single dose): Hormonal axis returns toward new baseline. In hypogonadal individuals, LH and FSH pulsatility may begin recovering. Testosterone normalization trajectory depends on pre-existing Leydig cell reserve.
Weeks 2–12 (chronic dosing): Progressive GnRHR downregulation leads to gonadotropin suppression; testosterone falls to castrate levels by week 3–4. Full suppression (testosterone <50 ng/dL) maintained with monthly or quarterly depot injections.

Cómo aprovecharlo al máximo

In prostate cancer, co-administer a non-steroidal antiandrogen (e.g., bicalutamide) for 2–4 weeks before and after first triptorelin injection to attenuate testosterone flare
Monitor bone mineral density annually with DEXA scan; supplement calcium and vitamin D; consider bisphosphonate co-therapy for long-term use
Baseline and quarterly ECG monitoring for QTc prolongation during androgen deprivation therapy
For off-label HPG reset: confirm pre-injection hypogonadism via serum LH, FSH, total testosterone, and prolactin; recheck at 4–6 weeks post-injection to assess response

Efectos secundarios comunes

Vasomotor hot flashes (up to 80% incidence with chronic use) — mediated by hypothalamic thermoregulatory disruption from estrogen withdrawal
Hypogonadal symptoms: decreased libido, erectile dysfunction, fatigue, sarcopenia — direct consequence of testosterone suppression
Initial disease flare in prostate cancer: PSA and bone pain can worsen transiently in first 1–2 weeks due to testosterone surge
Injection site reactions: local pain, induration, sterile abscess (rare with proper technique)

Mecanismo de acción

Triptorelin is a synthetic D-Trp6 analogue of native GnRH (also called LHRH), where substitution of L-glycine at position 6 with D-tryptophan confers resistance to enzymatic degradation and increased GnRH receptor binding affinity (~100× that of native GnRH). Upon binding to pituitary GnRH receptors (GnRHR, a Gαq/11-coupled GPCR), it activates phospholipase C-β, generating IP3 and DAG, which mobilize intracellular Ca2+ and activate PKC — ultimately triggering LH and FSH exocytosis. With continuous or repeated dosing, receptor internalization, uncoupling from G-proteins, and downregulation of GnRHR expression lead to complete pituitary desensitization, abolishing gonadotropin pulsatility. A single low dose (<500 mcg) avoids sustained receptor occupancy, allowing the transient LH/FSH flare without progressing to desensitization — the theoretical basis for the 'single-dose HPG reset' approach.

Triptorelin is absorbed rapidly after subcutaneous or intramuscular injection with a Tmax of approximately 1–3 hours (aqueous formulation). It binds extensively to pituitary GnRHRs with a Kd in the low nanomolar range. The LH surge peaks at 4–8 hours post-injection; FSH peaks slightly later (~6–10 hours). Downstream testosterone surge in males peaks at 24–72 hours. The aqueous half-life is ~7–8 hours; depot (microsphere) formulations achieve sustained plasma levels over 1 or 3 months. Metabolism occurs via peptidase cleavage; renal elimination of metabolites. Bioavailability via SC/IM routes is ~97%.

Farmacodinamia

Plasma triptorelin detectable within 15–30 minutes post-injection. LH surge begins at 2–4 hours; testosterone flare in 24–72 hours. Desensitization and gonadotropin suppression (with repeated dosing) becomes evident by 2–4 weeks of continuous administration.

Acutely: LH may rise 5–10× above baseline; FSH rises 2–4×; testosterone surges 1.5–3× above baseline within 72 hours. With chronic dosing: testosterone falls to castrate levels (<50 ng/dL) within 3–4 weeks. Bone mineral density losses of 2–5% annually are documented with long-term medical castration. Transient PSA flare is documented in prostate cancer patients during the initial surge phase.

Cronología

Hours 0–8: Rapid GnRHR binding initiates Gαq/11-PLC-β-IP3-Ca2+ signaling cascade. LH and FSH secreted in large, non-pulsatile bolus. Peak plasma LH at approximately 4–6 hours post-injection.
Days 1–3: Testosterone flare in males: serum levels rise to supranormal or high-normal range. In HPG-suppressed individuals, this represents functional axis response confirmation. PSA flare possible in prostate cancer patients.
Weeks 1–4 (single dose): Hormonal axis returns toward new baseline. In hypogonadal individuals, LH and FSH pulsatility may begin recovering. Testosterone normalization trajectory depends on pre-existing Leydig cell reserve.
Weeks 2–12 (chronic dosing): Progressive GnRHR downregulation leads to gonadotropin suppression; testosterone falls to castrate levels by week 3–4. Full suppression (testosterone <50 ng/dL) maintained with monthly or quarterly depot injections.

Comparaciones

Triptorelin Acetate — efectividad Very High, seguridad Caution, costo $$, Medium de usar
Leuprolide Acetate — efectividad Very High, seguridad Caution, costo $$$, Medium de usar
Gonadorelin (native GnRH) — efectividad High, seguridad Moderate, costo $$, Medium de usar
hCG (human Chorionic Gonadotropin) — efectividad High, seguridad Good, costo $$, Medium de usar

Efectos adversos

Comunes:

Vasomotor hot flashes (up to 80% incidence with chronic use) — mediated by hypothalamic thermoregulatory disruption from estrogen withdrawal
Hypogonadal symptoms: decreased libido, erectile dysfunction, fatigue, sarcopenia — direct consequence of testosterone suppression
Initial disease flare in prostate cancer: PSA and bone pain can worsen transiently in first 1–2 weeks due to testosterone surge
Injection site reactions: local pain, induration, sterile abscess (rare with proper technique)

Raros:

Anaphylactic/anaphylactoid reactions (<0.1% incidence): urticaria, bronchospasm, hypotension — GnRH receptor-mediated or excipient hypersensitivity
QT interval prolongation with chronic androgen deprivation therapy — associated with cardiovascular mortality risk
Pituitary apoplexy (extremely rare): hemorrhage or infarction in existing pituitary adenoma triggered by GnRH flare
Spinal cord compression in prostate cancer metastases due to initial testosterone flare (<1%)

Contraindicaciones y mitigación de riesgos

Contraindicado en:

Patients with hormone-sensitive prostate cancer and vertebral metastases (flare may precipitate spinal cord compression; antiandrogen flare protection required)
Women with undiagnosed abnormal uterine bleeding or suspected estrogen-dependent malignancy
Individuals with known pituitary adenoma (risk of apoplexy)
Patients on QT-prolonging medications (additive cardiac risk via androgen deprivation)
Individuals with osteoporosis or significant bone mineral density deficit (accelerated bone loss)

In prostate cancer, co-administer a non-steroidal antiandrogen (e.g., bicalutamide) for 2–4 weeks before and after first triptorelin injection to attenuate testosterone flare
Monitor bone mineral density annually with DEXA scan; supplement calcium and vitamin D; consider bisphosphonate co-therapy for long-term use
Baseline and quarterly ECG monitoring for QTc prolongation during androgen deprivation therapy
For off-label HPG reset: confirm pre-injection hypogonadism via serum LH, FSH, total testosterone, and prolactin; recheck at 4–6 weeks post-injection to assess response

Reference data

Specifications

Molecular formula: C64H82N18O13 · C2H4O2
Molecular weight: 1311.47 g/mol (free base ~1269.43 g/mol)
Half-life: ~7–8 hours (aqueous); depot formulations release over 1–3 months
Route: Subcutaneous, Intramuscular
Cycle length: Single dose for HPG reset; 3–6 months for clinical indications; ongoing for prostate cancer
Storage: Store lyophilized powder at 2–8°C (refrigerated). Protect from light and moisture. Once reconstituted, store at 2–8°C and use within 24–48 hours. Do not freeze reconstituted solution. Keep out of reach of children.
Legal status: Prescription-only pharmaceutical in the USA, EU, and most jurisdictions. Research-grade peptide vials available through peptide suppliers but not approved for self-administration. Classified as a pharmaceutical, not a controlled substance in most countries.

FAQ

Common questions

What is the pharmacological basis for the 'single-dose triptorelin HPG reset' protocol?

The hypothesis is rooted in pituitary GnRHR pharmacodynamics. Anabolic steroid use suppresses hypothalamic GnRH pulsatility via negative feedback from exogenous androgens, leading to pituitary GnRHR sensitization through disuse. A single low-dose triptorelin injection (100–500 mcg) provides an artificial GnRH pulse that stimulates the sensitized pituitary to release LH and FSH, mimicking the first natural pulse of HPG axis recovery. This approach has biological plausibility but lacks RCT-level evidence specifically for post-AAS hypogonadism. The protocol was discussed in Scally & Kazmer (2003) in an endocrine case series, and has been extrapolated from GnRH pulse therapy literature.

How does triptorelin compare pharmacologically to native GnRH and other GnRH analogues (leuprolide, buserelin)?

Triptorelin's D-Trp6 substitution increases receptor binding affinity and resistance to peptidase degradation versus native GnRH. Compared to leuprolide (D-Leu6) and buserelin (D-Ser6), triptorelin has broadly similar clinical efficacy for castration in prostate cancer; meta-analyses show no significant superiority among approved GnRH agonists. Triptorelin's half-life (~7–8 hours aqueous) is comparable to leuprolide; depot formulations are pharmacologically interchangeable for most indications.

Is there evidence for fertility restoration with triptorelin?

Triptorelin has demonstrated efficacy in ovarian stimulation protocols (triggering LH surge for oocyte maturation) and in protecting ovarian function during chemotherapy via transient GnRH-mediated ovarian quiescence (POEMS trial, Moore et al., NEJM 2015). Direct evidence for male fertility restoration via HPG reset is limited to case reports and the biological rationale. Pulsatile GnRH administration (not continuous agonist) is the established treatment for hypogonadotropic hypogonadism-related infertility.

What is the evidence level?

This compound is classified as Clinical evidence. Randomized controlled trial data in humans exists and supports use in specific contexts.

Research

Research & sources

Clinical evidence

Current evidence for Triptorelin Acetate is rated as Clinical evidence. Human clinical evidence supports the reported effects.

1. Moore HC et al. Goserelin for ovarian protection during breast-cancer adjuvant chemotherapy (POEMS/S0230) (2015) — New England Journal of Medicine 2015;372:923–932
2. Triptorelin in the management of prostate cancer: pharmacology, clinical efficacy, and tolerability (2007) — Therapeutics and Clinical Risk Management 2007;3(3):433–448
3. Crawford ED et al. Leuprolide with and without flutamide in prostate cancer — implications for GnRH analogue flare management (1989) — New England Journal of Medicine 1989;321:419–424
4. Scally MC, Kazmer JJ. A novel strategy for the use of gonadotropin-releasing hormone (GnRH) agonists in the treatment of steroid-induced hypogonadotrophic hypogonadism (2003) — European Journal of Clinical Pharmacology 2003;59:21–26

Explore

Often discussed alongside

Gonadorelin · sexual PT-141 (Bremelanotide) · sexual IGF-1 LR3 · growth