GHRP-6 vs GHRP-2 — Dose Comparison and Volume Planner

Published 2026-09-04 · Lyophile Editorial

GHRP-2 is ~5× more potent per µg than GHRP-6. Standard research doses: 100 µg GHRP-2 vs 200 µg GHRP-6. Below is the full syringe math for both peptides at the most common reconstitution ratio.

Reconstitution Calculator: 5 mg Vial + 2 mL Bacteriostatic Water

5 mg peptide in 2 mL diluent = 2500 µg/mL = 25 µg per unit on a U-100 insulin syringe.

A U-100 syringe holds 100 units per 1 mL. Each unit mark = 0.01 mL. At this concentration:

• 200 µg GHRP-6 → draw to 8 units
• 100 µg GHRP-2 → draw to 4 units

Step-by-step math

1. Convert peptide mass: 5 mg = 5000 µg
2. Divide by diluent volume: 5000 µg ÷ 2 mL = 2500 µg/mL
3. Divide by syringe capacity: 2500 µg/mL ÷ 100 units/mL = 25 µg per unit
4. Calculate your draw: 200 µg ÷ 25 µg/unit = 8 units | 100 µg ÷ 25 µg/unit = 4 units

Full Dose-to-Syringe Table (2500 µg/mL concentration)

| Dose (µg) | Volume (mL) | U-100 draw | GHRP-6 use | GHRP-2 use | |---|---|---|---|---| | 50 µg | 0.02 mL | 2 units | — | Half-dose protocol | | 100 µg | 0.04 mL | 4 units | Half-dose protocol | Standard dose | | 150 µg | 0.06 mL | 6 units | Common dose | — | | 200 µg | 0.08 mL | 8 units | Standard dose | High-dose protocol | | 250 µg | 0.10 mL | 10 units | High-dose protocol | — |

Reading the syringe: draw to the 8-unit line → 200 µg. Draw to 4 units → 100 µg. Same arithmetic for both peptides because the concentration is identical.

Alternative Reconstitution: 5 mg Vial + 1 mL Diluent

5000 µg/mL = 50 µg per unit on a U-100 syringe.

• 200 µg dose → 4 units
• 100 µg dose → 2 units

Tradeoff: smaller injection volumes, but error margin shrinks. A half-unit misread changes the dose by 25 µg (vs 12.5 µg at 2 mL reconstitution). The 2 mL ratio is more forgiving and is the default throughout this guide.

Dose Difference: GHRP-6 vs GHRP-2

| Parameter | GHRP-6 | GHRP-2 | |---|---|---| | Typical research dose | 200 µg | 100 µg | | Relative GH-release potency | 1× (baseline) | ~5× per µg | | Hunger side-effect intensity | Strong, dose-dependent | Mild to moderate | | Half-life (published range) | ~60–90 min | ~30–45 min | | Ghrelin receptor affinity | High | Higher | | Common protocol frequency | 2–3× daily | 2–3× daily |

Vial yield: 5 mg GHRP-6 at 200 µg doses = 25 injections. Same vial of GHRP-2 at 100 µg = 50 injections.

Hunger Effect Comparison

GHRP-6 produces markedly stronger appetite stimulation than GHRP-2 at receptor-equivalent doses — a direct consequence of its binding profile at GHSR-1a and longer receptor residence time. Effect is dose-dependent.

| Dose | GHRP-6 hunger effect | GHRP-2 hunger effect | |---|---|---| | 100 µg | Moderate | Minimal to mild | | 200 µg | Strong | Mild to moderate | | 300 µg | Pronounced | Moderate |

Timing: GHRP-6 hunger peaks ~20–30 minutes post-injection, tapering over the following hour. GHRP-2 at 100 µg typically produces minimal hunger in most research subjects.

Protocol implication: If appetite is an observational endpoint, GHRP-6 gives the clearer signal. If you want GH-axis stimulation without hunger-driven behavior confounds, GHRP-2 at 100 µg is the cleaner tool.

Half-Life Difference

| Peptide | Half-life | Dosing implication | |---|---|---| | GHRP-6 | ~60–90 min | Supports wider spacing between injections | | GHRP-2 | ~30–45 min | More frequent administration needed to maintain GH pulse amplitude |

Some protocols run GHRP-2 three times daily and GHRP-6 twice daily for this reason, though both are commonly injected 2–3× per day. The half-life gap also explains why GHRP-6's hunger signal feels more sustained.

Selection Guide

| Decision factor | Choose GHRP-2 | Choose GHRP-6 | |---|---|---| | Primary endpoint | GH release | GH release + appetite | | Dose per injection | 100 µg | 200 µg | | Injections per 5 mg vial | 50 | 25 | | Hunger confound | Low | High | | Half-life | Shorter (~30–45 min) | Longer (~60–90 min) | | Syringe draw (2 mL recon) | 4 units | 8 units |

Practical Planning Notes

Syringe precision: U-100 syringes are marked in 1-unit increments. At 2500 µg/mL, each unit = 25 µg. 200 µg GHRP-6 = exactly 8 units. 100 µg GHRP-2 = exactly 4 units. Both land on integer markings — no estimating between lines.

Vial overfill: Most peptide vials contain 5–10% overfill above label claim. A "5 mg" vial may hold 5.25–5.5 mg. Your last dose may be slightly stronger than calculated, or you may get one extra dose.

Reconstitution accuracy: Use a 1 mL or 3 mL syringe to measure bacteriostatic water — not the U-100 insulin syringe. Drawing 2 mL in a U-100 syringe requires two full 1 mL draws, each introducing small error. A single 3 mL draw is more accurate.

Bacteriostatic water: 0.9% benzyl alcohol is the standard preservative concentration per USP guidelines. It is bacteriostatic — inhibits bacterial growth but does not sterilize. Use sterile technique throughout.

Reconstitution Steps

1. Wipe vial stopper with alcohol swab
2. Draw 2 mL bacteriostatic water into a 3 mL syringe
3. Inject slowly along the vial wall — do not jet directly onto lyophilized powder
4. Swirl gently until dissolved. Do not shake — shaking can denature the peptide
5. Refrigerate. Use within 30 days of reconstitution

Sources

Bacteriostatic water:

• BAC Water Depot — USP-grade 0.9% benzyl alcohol water, multi-dose vials
• Peptide Warehouse — pre-filled vials, sterile filtration documented
• PurePep — 30 mL vials, sealed and labeled

Research peptides:

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped GHRP-6 and GHRP-2
• Research Chem Supply — third-party tested, lyophilized in sealed vials
• Limitless Life — GHRP-6 and GHRP-2, COA on request

For research use only — not clinical guidance. All peptide handling should follow institutional biosafety protocols. Verify your source's COA before reconstitution.