Side-by-side · Research reference

GHRP-2vsTirzepatide

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

APhase 2Reviewed15/42 cited

BFDA-ApprovedVerified14/45 cited

GHRP-2

Hexapeptide GHRP · Phase 2 (clinical diagnostic)

100–300 mcgPer doseBowers 1990

Phase 2Evidence levelBowers 1990 Sigalos 2018

~30 minHalf-lifeMalagón 1999

SQ · Multiple sites · 1–3×/day

Tirzepatide

GIP+GLP-1 Dual Agonist · FDA-Approved

2.5–15 mgWeekly doseZEPBOUND (tirzepatide) injecti 2023

20.9%Body-weight ↓Jastreboff 2022

~5 daysHalf-lifeZEPBOUND (tirzepatide) injecti 2023

SQ · Abdomen / thigh / arm · Once weekly

01Mechanism of Action

Parameter

GHRP-2

Tirzepatide

Primary target

Ghrelin receptor (GHS-R1a) on anterior pituitaryBowers 1990

GIP receptor (GIPR) + GLP-1 receptor (GLP-1R)Frias 2018

Pathway

GHS-R1a → Gαq → Ca²⁺ → GH vesicle exocytosisBowers 2002

Dual GIPR/GLP-1R agonism → ↑insulin (glucose-dependent), ↓glucagon, ↓gastric emptying, ↓appetite, ↑energy expenditure (via GIP component)Jastreboff 2022 Frias 2018

Downstream effect

Strong GH pulse + IGF-1 elevation; appetite increase via ghrelin agonismBowers 2002

Profound glycemic improvement and weight reduction; cardiometabolic benefitsJastreboff 2022

Feedback intact?

Yes, with somatostatin feedback active

Glucose-dependent insulin release preserves physiological feedback

Origin

Synthetic hexapeptide; developed by Bowers/Tulane group in the 1980sBowers 1990

39-AA peptide with C-20 fatty-acid acylation. Single molecule with balanced GIP + GLP-1 affinityFrias 2018

Antibody development

—

02Dosage Protocols

Parameter

GHRP-2

Tirzepatide

Standard dose

100–300 mcg per injectionBowers 1990

—

Frequency

1–3× per day

—

Lower / starter dose

50 mcg per dose

—

Evidence basis

Phase 2 + clinical diagnostic useBowers 1990

FDA-approved · Phase 3 RCTs (SURMOUNT, SURPASS)Jastreboff 2022 ZEPBOUND (tirzepatide) injecti 2023

Duration

8–12 weeks on / 4 off (anecdotal)

Indefinite for chronic indication

Reconstitution

Bacteriostatic water

Pre-filled commercial pen. Research vial: bacteriostatic water per label.

Timing

Pre-sleep + fasted preferred

Once weekly, any time of day

Half-life

~30 minMalagón 1999

~5 days (116 h)ZEPBOUND (tirzepatide) injecti 2023

Standard dose (T2D)

—

5–15 mg / weekZEPBOUND (tirzepatide) injecti 2023

Standard dose (weight)

—

5, 10, or 15 mg / week (titrated)ZEPBOUND (tirzepatide) injecti 2023 Jastreboff 2022

Titration schedule

—

2.5 mg → +2.5 mg every 4 weeks → 15 mg max

Slower titration mitigates GI side effects.

04Side Effects & Safety

Parameter

GHRP-2

Tirzepatide

Cortisol elevation

Mild but measurableBowers 1990

—

Prolactin elevation

Mild but measurable

—

Hunger

Strong appetite increase

—

Injection site reaction

Mild erythema

Mild erythema, pruritus

IGF-1 elevation

Strong; monitor with chronic high-dose use

—

Cancer risk

Contraindicated in active malignancy

—

Pregnancy / OB

Avoid

Contraindicated

GI symptoms

—

Nausea, vomiting, diarrhea (common, dose-dependent)Jastreboff 2022

Pancreatitis risk

—

Rare; discontinue if suspectedZEPBOUND (tirzepatide) injecti 2023

Thyroid C-cell tumours

—

Boxed warning — contraindicated in MEN2 / MTC historyZEPBOUND (tirzepatide) injecti 2023

Hypoglycemia

—

Low as monotherapy; risk with sulfonylureas / insulin

Gallbladder events

—

Increased cholelithiasis

Diabetic retinopathy

—

Rapid glycemic improvement may transiently worsen

Absolute Contraindications

GHRP-2

·Active malignancy
·Pregnancy / breastfeeding

Tirzepatide

·MTC personal or family history; MEN2
·Pregnancy / breastfeeding
·Hypersensitivity to tirzepatide

Relative Contraindications

GHRP-2

·Untreated diabetes

Tirzepatide

·Severe gastroparesis
·History of pancreatitis
·Diabetic retinopathy

05Administration Protocol

Parameter

GHRP-2

Tirzepatide

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.

Commercial: pre-filled pen / vial. Research lyophilised: bacteriostatic water per label.

2. Injection site

SQ — abdomen or thigh. Rotate sites.

SQ — abdomen, thigh, or upper arm. Rotate weekly.

3. Timing

Pre-sleep + fasted preferred.

Once weekly, same day. Day change allowed if ≥3 days separate doses.

4. Storage

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

Refrigerate 2–8 °C unopened. Room temp ≤30 °C up to 21 days after first use.

5. Needle

29–31G, 4–8 mm insulin syringe.

Pen-supplied. Research vial: 27–31G insulin syringe.

06Stack Synergy

GHRP-2

+ CJC-1295 (no DAC)

Strong

View CJC-1295 (no DAC) →

GHRP-2 + CJC-1295-no-DAC is a higher-amplitude alternative to the ipamorelin + CJC-1295 stack. GHRP-2 produces a stronger pulse but with cortisol + prolactin signal — choose when maximum GH amplitude is the goal and the side-effect tolerance is acceptable.

GHRP-2: 100–200 mcg SQ · pre-sleep
CJC-1295 (no DAC): 100 mcg SQ · same injection
Primary benefit: High-amplitude GH pulse, body composition

Bowers 1990 Teichman 2006

Tirzepatide

— no documented stacks