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PEPTIDE HALF-LIFE GUIDE
Research Reference
Peptide Half-Life Guide: How Long Do Research Peptides Stay Active?
Half-life is the single most important pharmacokinetic parameter in peptide research. It determines dosing frequency, steady-state concentration, and total clearance time. This guide covers the half-lives of every major research peptide we stock, explains why they differ so dramatically (from 30 minutes to 8 days), and includes an interactive simulator so you can visualise decay curves for any compound.
What Is Peptide Half-Life?
Half-life (t1/2) is the time it takes for the concentration of a peptide to decrease by exactly 50%. After one half-life, 50% of the original amount remains. After two half-lives, 25% remains. After three, 12.5%. After roughly 4.5 half-lives, over 95% has been cleared – generally considered “full elimination.”
For researchers, half-life determines three practical things:
1. Dosing frequency – A peptide with a 30-minute half-life (like CJC-1295 no DAC) needs frequent administration. One with a 7-day half-life (CJC-1295 with DAC) requires far less frequent dosing.
2. Steady-state levels – Repeated dosing at intervals shorter than elimination time causes accumulation until reaching steady state. Longer half-lives produce higher accumulation.
3. Clearance time – Important for washout periods. A 2-hour half-life clears in roughly 9 hours. A 168-hour half-life takes over a month.
Complete Peptide Half-Life Reference Chart
The following table covers every major research peptide we stock, organised from shortest to longest half-life. Each compound links to its product page.
| Peptide | Half-Life | 95% Clearance | Category |
|---|---|---|---|
| Oxytocin | ~3-5 min (IV) | ~22 min | Neuropeptide |
| Sermorelin | ~10-20 min | ~1.5 hours | Growth Hormone |
| IGF-1 DES | ~20 min | ~1.5 hours | Growth Hormone |
| CJC-1295 no DAC (MOD GRF) | ~30 min | ~2.2 hours | Growth Hormone |
| Melanotan 2 | ~33 min | ~2.5 hours | Skin & Tanning |
| AOD-9604 | ~30-45 min | ~3.5 hours | Weight Mgmt |
| GHRP-2 | ~1.5 hours | ~7 hours | Growth Hormone |
| Ipamorelin | ~2 hours | ~9 hours | Growth Hormone |
| GHRP-6 | ~2 hours | ~9 hours | Growth Hormone |
| TB-500 | ~2 hours (est.) | ~9 hours | Recovery |
| Thymosin Alpha-1 | ~2 hours | ~9 hours | Immune |
| PT-141 (Bremelanotide) | ~2.5 hours | ~11 hours | Sexual Health |
| BPC-157 | ~4 hours (est.) | ~18 hours | Recovery |
| Semax | ~4 hours (nasal) | ~18 hours | Cognitive |
| SS-31 (Elamipretide) | ~4 hours | ~18 hours | Anti-Ageing |
| Epithalon (Epitalon) | ~6 hours (est.) | ~27 hours | Anti-Ageing |
| Selank | ~12 hours (nasal) | ~2.2 days | Cognitive |
| CJC-1295 with DAC | ~6-8 days | ~30-35 days | Growth Hormone |
Note: Values are approximate, derived from published preclinical and clinical PK data. Values marked “(est.)” have limited published data and are estimated from structural analogues. Actual values vary by route, model, and conditions.
Interactive Half-Life Decay Simulator
Select a preset or enter custom values to visualise the decay curve, steady-state accumulation, and clearance time over 7 days.
Why Do Peptide Half-Lives Vary So Much?
The range spans from 3 minutes (Oxytocin IV) to 8 days (CJC-1295 with DAC) – a 3,800-fold difference. Three factors explain this:
1. Enzymatic degradation. Most peptides are rapidly degraded by peptidases (DPP-IV, aminopeptidases, neutral endopeptidases) in blood and tissue. Modifications that resist enzymatic cleavage – like the four amino acid substitutions in CJC-1295 that block DPP-IV – dramatically extend half-life. N-acetylation (as in N-Acetyl Semax) protects the N-terminus from aminopeptidases.
2. Renal clearance. Small peptides (under ~5 kDa) are rapidly filtered by the kidneys. Larger peptides or those bound to carrier proteins avoid renal filtration. CJC-1295 with DAC achieves its 7-day half-life because the Drug Affinity Complex binds covalently to albumin (66 kDa), creating a molecule far too large for glomerular filtration.
3. Route of administration. The same peptide can have different effective half-lives depending on delivery. Selank given IV has a very short half-life, but intranasal delivery creates a depot effect extending functional activity to approximately 12 hours. PEGylation (as in PEG-MGF) shields the peptide from protease access.
Half-Lives by Research Category
Recovery peptides (Recovery & Repair): BPC-157 and TB-500 both have short half-lives (2-4 hours), typically requiring daily administration. However, their biological effects (tissue remodelling, angiogenesis) persist well beyond plasma presence due to downstream signalling cascades. The TB-500 + BPC-157 blend simplifies daily protocols.
Growth hormone secretagogues (GH peptides): This category shows the widest range. CJC-1295 no DAC and Sermorelin have half-lives under 30 minutes for quick GH pulses. Ipamorelin and GHRP-2 last 1.5-2 hours. CJC-1295 with DAC lasts 6-8 days for sustained elevation.
Nootropic peptides (Cognitive & Nootropic): Semax (~4h) and Selank (~12h nasal) have moderate half-lives. N-acetylated variants extend these further.
Anti-ageing peptides (Anti-Ageing & Longevity): Epithalon (~6h), SS-31 (~4h), and MOTS-c have moderate half-lives but their downstream effects (telomerase activation, cardiolipin stabilisation) persist far beyond plasma presence. FOX04-DRI uses D-retro-inverso design to resist proteases entirely.
Steady State and Accumulation
When a peptide is administered at regular intervals, each dose adds to residual levels from previous doses. This creates accumulation until the amount eliminated per interval equals the amount administered – the steady state.
Steady state is reached after approximately 4-5 half-lives of repeated dosing. For Ipamorelin (t1/2 ~2h) dosed daily, steady state is reached within the first day. For CJC-1295 with DAC (t1/2 ~7 days) dosed weekly, steady state takes about 5 weeks.
Use the simulator above to see this: toggle between “Single Dose Only” and a repeated interval to visualise accumulation. The steady-state peak for CJC-1295 DAC at 5mg weekly is approximately 9.1mg – nearly double the single-dose peak.
Frequently Asked Questions
What is the half-life of BPC-157?
BPC-157 has an estimated half-life of approximately 4 hours. Published pharmacokinetic data is limited, but its biological effects persist beyond the plasma half-life. Most research protocols use daily administration.
What is the half-life of CJC-1295?
CJC-1295 without DAC (MOD GRF 1-29): ~30 minutes. CJC-1295 with DAC: 6-8 days. The largest half-life difference between two versions of the same base peptide.
Does a longer half-life mean a peptide is more effective?
No. Half-life and efficacy are independent. For GH-axis research, the short half-life of CJC-1295 no DAC is often preferred because it produces pulsatile release mimicking natural physiology, whereas the DAC version produces sustained non-physiological elevation.
How long until a peptide is fully cleared?
Roughly 4.5 half-lives for 95% clearance. A 2-hour half-life clears in ~9 hours. CJC-1295 DAC (7-day half-life) takes ~30-35 days. The simulator above calculates this for any compound.
Do N-acetylated peptides have longer half-lives?
Generally yes. N-acetylation protects the N-terminus from aminopeptidase degradation. N-Acetyl Semax outlasts standard Semax, and N-Acetyl Selank outlasts standard Selank.
Where can I buy these peptides in the UK?
All peptides in this guide are available from BioLab Peptides with same-day UK dispatch, 99%+ HPLC purity, and CoA included. Reconstitution supplies: Accessories & Supplies.
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Shop All Peptides →Research Use Only: All products sold by BioLab Peptides are intended strictly for laboratory and research purposes. They are not intended for human or veterinary consumption. Half-life values are derived from published pharmacokinetic data and provided for educational reference only.
