Side-by-side · Research reference

SermorelinvsTriptorelin

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 3HUMAN-REVIEWED14/43 cited

BFDA-ApprovedHUMAN-REVIEWED16/64 cited

Sermorelin

GHRH 1-29 fragment · Short-acting

100–500 mcgPer doseMolteno 2013

Phase 3Evidence levelWalker 1994 Molteno 2013

~12 minHalf-lifeMolteno 2013

SQ · Pre-sleep · 1×/day

Triptorelin

GnRH Agonist · FDA-Approved

3.75–22.5 mgDepot dose rangeYee 2025 Chen 2024

<50 ng/dLTestosterone target

1–6 monthsDepot durationYee 2025 Chen 2024

IM · Depot Injection · Monthly to 6-MonthlyYee 2025

01Mechanism of Action

Parameter

Sermorelin

Triptorelin

Primary target

Pituitary GHRH receptorWalker 1994

Pituitary GnRH receptorsUnknown 2012

Pathway

GHRH-R → Gαs → cAMP → PKA → GH vesicle exocytosisWalker 1994

GnRH receptor agonism → initial flare (LH/FSH spike) → receptor desensitization → sustained LH/FSH suppression

Downstream effect

Pulsatile GH release; subsequent IGF-1 elevationMolteno 2013

Castration-level suppression of testosterone (men) and estrogen (women) within 2–4 weeks post-flare

Feedback intact?

Yes — short pulse preserves feedback

No — bypasses physiological pulsatility; continuous agonism produces paradoxical suppression

Origin

Unmodified active 29-AA fragment of human GHRH (1-44)Walker 1994

Synthetic decapeptide analogue of native GnRH with amino acid substitutions for enhanced receptor affinity and stability

Antibody development

—

02Dosage Protocols

Parameter

Sermorelin

Triptorelin

Standard dose

100–500 mcg per injectionMolteno 2013

—

Frequency

Once daily, pre-sleep

Every 1, 3, or 6 months per formulation

Lower / starter dose

100 mcg per dose

—

Evidence basis

Phase 3 (Geref pediatric); clinical practiceWalker 1994 Molteno 2013

Multiple Phase 3 RCTs · FDA-approved 1999

Duration

8–12 weeks per cycle

—

Reconstitution

Bacteriostatic water

—

Timing

Pre-sleep, fasted preferred

—

Half-life

~12 min (plasma)Molteno 2013

Shorter than tesamorelin (~26 min) — simpler GHRH analogue.

—

1-month depot

—

3.75 mg IM

Most common formulation for prostate cancer.

3-month depot

—

11.25 mg IMYee 2025

Reduced injection frequency.

6-month depot

—

22.5 mg IMYee 2025 Chen 2024

Long-acting formulation; improved adherence in real-world use.Yee 2025

Administration route

—

Intramuscular (IM) — gluteal or deltoid

Indication: Prostate cancer

—

Advanced (metastatic or locally advanced)

Androgen deprivation therapy (ADT) backbone.

Indication: Endometriosis

—

3.75 mg monthly

FDA-approved; typically 6-month course.

Indication: Central precocious puberty

—

Pediatric use (≥2 years)Jia 2025

Weight-based dosing per FDA label.

Duration (prostate cancer)

—

Continuous or intermittent ADT protocolsPreston 2024

Intermittent ADT may reduce side effects; cardiovascular risk similar to continuous.

Monitoring

—

Serum testosterone, PSA (prostate cancer), bone density, lipids, glucose

04Side Effects & Safety

Parameter

Sermorelin

Triptorelin

Injection site reaction

Mild erythema, transient pain

—

Flushing / headache

Common transient effect

—

IGF-1 elevation

Modest at standard doses

—

Cancer risk

Contraindicated in active malignancy (GH/IGF-1 axis)

—

Pregnancy / OB

Avoid

—

Glucose handling

Generally neutral

—

Initial flare symptoms

—

Bone pain, urinary obstruction, spinal cord compression (first 2 weeks)

Antiandrogen co-treatment (bicalutamide) mitigates flare in metastatic disease.

Cardiovascular events

—

MI, stroke, arrhythmia — GnRH agonists show higher CV risk vs antagonists in meta-analysesPatel 2025 Preston 2024

Hot flashes

—

Very common (>60%); vasomotor instability

Bone loss / Osteoporosis

—

Accelerated bone mineral density decline; fracture risk ↑Friedrich 2025

Baseline DEXA scan recommended; bisphosphonates or denosumab may be indicated.

Metabolic syndrome

—

Weight gain, insulin resistance, dyslipidemia, diabetes risk

Sexual dysfunction

—

Erectile dysfunction, loss of libido (expected pharmacological effect)Jia 2025

Injection site reactions

—

Pain, erythema, sterile abscess (rare with depot formulations)

Gynecomastia / Breast tenderness

—

Common (10–20%); peripheral aromatization of residual androgens

Fatigue / Mood changes

—

Anemia, depression, cognitive changes reported in long-term ADT

Hepatotoxicity

—

Transient transaminase elevations; clinically apparent liver injury rare

Racial differences (ADT)

—

Black veterans show higher CV event rates vs White veterans on GnRH agonists

Absolute Contraindications

Sermorelin

·Active malignancy
·Pregnancy / breastfeeding
·Disrupted hypothalamic-pituitary axis

Triptorelin

·Hypersensitivity to triptorelin, GnRH, or GnRH agonist analogues
·Pregnancy (Category X)

Relative Contraindications

Sermorelin

·Untreated diabetes

Triptorelin

·Active cardiovascular disease — consider GnRH antagonist alternative
·Metastatic vertebral disease with spinal cord compression risk (flare hazard)
·Severe urinary obstruction — may worsen during flare
·Osteoporosis or high fracture risk (requires bone-protective therapy)

05Administration Protocol

Parameter

Sermorelin

Triptorelin

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL = 250 mcg per 0.1 mL.

Choose 1-month (3.75 mg), 3-month (11.25 mg), or 6-month (22.5 mg) depot based on adherence needs and clinical context. 6-month formulation shows improved real-world adherence in Asia-Pacific cohorts.

2. Injection site

SQ — abdomen or thigh. Rotate sites.

Intramuscular — gluteal or deltoid muscle. Use 21–23G needle. Aspirate to confirm non-vascular placement. Rotate sites with repeat injections.

3. Timing

Pre-sleep, fasted.

For metastatic prostate cancer: co-administer antiandrogen (e.g., bicalutamide 50 mg daily) starting 1 week before first injection and continuing 2–4 weeks to prevent tumor flare.

4. Storage

Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.

Baseline: testosterone, PSA, bone density (DEXA), lipids, glucose. Follow-up: testosterone at 4 weeks (confirm <50 ng/dL castration), PSA monthly × 3, then quarterly. Annual DEXA for bone loss.

5. Needle

29–31G, 4–8 mm insulin syringe.

Store vials at room temperature (20–25 °C), protect from light. Do not freeze. Reconstituted suspension should be used immediately.

6. Intermittent ADT protocol (optional)

—

Some protocols use on-treatment periods (9–12 months) alternating with off-treatment intervals until PSA rises. Cardiovascular risk appears similar to continuous ADT.

06Stack Synergy

Sermorelin

+ Ipamorelin

Strong

View Ipamorelin →

Sermorelin (GHRH analogue) and ipamorelin (selective GHRP) form the prototypical GHRH+GHRP dual-axis stack at the lowest cost. Both peak within 30 min and produce a sharp physiological GH pulse without cortisol/prolactin elevation.

Sermorelin: 200–300 mcg SQ · pre-sleep
Ipamorelin: 200–300 mcg SQ · same injection
Primary benefit: Pulsatile GH stimulation, recovery, body composition

Raun 1998 Walker 1994

Triptorelin

— no documented stacks