Finding peptide half-life data usually means digging through a dozen Reddit threads and hoping someone cited an actual study. This is the consolidated reference — 35+ research peptides with half-lives, routes, and sources in one table.
A quick note on data quality: some peptides have published pharmacokinetic studies with precise half-life measurements in humans. Others have only animal data or community-estimated values. The table marks which is which so you know what you’re working with.
What half-life means (and what it doesn’t)
Elimination half-life is the time it takes for plasma concentration to drop by 50%. After about 4-5 half-lives, the compound is effectively cleared. This determines dosing frequency in research protocols.
Half-life is NOT the same as duration of action. BPC-157 has a very short half-life (~minutes IV), but its downstream effects on gene expression and signaling pathways persist much longer. Semaglutide’s 7-day half-life aligns well with its duration of action because it works through sustained receptor occupancy. Different mechanisms, different relationships.
Factors that affect half-life: molecular weight (larger = generally longer), modifications (fatty acid acylation, PEGylation, DAC conjugation), route of administration (IV is fastest clearance, subQ creates a depot), and protein binding (albumin binding dramatically extends half-life).
Complete peptide half-life reference table
| Peptide | Half-Life | Route | Category | Data Source |
|---|---|---|---|---|
| GLP-1 Receptor Agonists | ||||
| Semaglutide | ~168 hours (7 days) | SubQ / Oral | GLP-1 agonist | Published PK (Lau et al., 2015, PMID: 25943033) |
| Tirzepatide | ~120 hours (5 days) | SubQ | GIP/GLP-1 dual agonist | Published PK (Coskun et al., 2018, PMID: 30305981) |
| Retatrutide | ~144 hours (6 days) | SubQ | GIP/GLP-1/GCGR triple agonist | Phase 2 PK data (Jastreboff, 2023, PMID: 37385275) |
| Exenatide | ~2.4 hours | SubQ | GLP-1 agonist | Published PK (FDA label) |
| Liraglutide | ~13 hours | SubQ | GLP-1 agonist | Published PK (FDA label) |
| Cagrilintide | ~7 days | SubQ | Amylin analog | Published PK (Enebo et al., 2021, PMID: 34081854) |
| Growth Hormone Secretagogues | ||||
| CJC-1295 DAC | ~8 days | SubQ | GHRH analog (DAC-conjugated) | Published PK (Teichman et al., 2006, PMID: 16352683) |
| CJC-1295 (no DAC) | ~30 minutes | SubQ | GHRH analog | Published PK (Teichman et al., 2006) |
| Ipamorelin | ~2 hours | SubQ / IV | Ghrelin mimetic | Published PK (Raun et al., 1998, PMID: 9849822) |
| GHRP-2 | ~15-25 minutes | SubQ / IV | Ghrelin mimetic | Published PK (Bowers et al., 1991) |
| GHRP-6 | ~15-20 minutes | SubQ / IV | Ghrelin mimetic | Published PK (Bowers, 1998) |
| MK-677 (Ibutamoren) | ~4-6 hours | Oral | GH secretagogue (non-peptide) | Published PK (Nass et al., 2008, PMID: 18981485) |
| Sermorelin | ~10-20 minutes | SubQ / IV | GHRH analog | Published PK (FDA label) |
| Hexarelin | ~60 minutes | SubQ / IV | Ghrelin mimetic | Published PK |
| Healing & Recovery Peptides | ||||
| BPC-157 | ~2 min (IV), est. 4-6 hr (subQ depot) | SubQ / Oral | Gastric pentadecapeptide | Animal PK data (estimated from detection windows) |
| TB-500 | Est. 2-4 hours | SubQ | Tβ4 fragment | Estimated (limited published PK) |
| GHK-Cu | Est. 30-60 minutes | SubQ / Topical | Copper tripeptide | Estimated (Pickart, 2008) |
| Thymosin Beta-4 (full) | Est. 1-2 hours | SubQ / IV | Actin-sequestering protein | Estimated from clinical studies |
| KPV | Est. 20-30 minutes | SubQ / Oral | α-MSH fragment | Estimated |
| Nootropic Peptides | ||||
| Selank | ~30 sec – 3 min (native) / longer for analogs | Intranasal / SubQ | Tuftsin analog | Published PK (Zozulia et al., 2008) |
| Semax | ~30 sec – 3 min (native) | Intranasal | ACTH 4-7 analog | Published PK (Russian literature) |
| Dihexa | Est. 2-4 hours | SubQ / Oral (proposed) | HGF mimetic | Estimated from animal studies |
| DSIP | ~15-30 minutes | IV / SubQ | Nonapeptide | Published PK (Kafi et al., 1979) |
| Immune & Anti-Inflammatory | ||||
| Thymosin Alpha-1 (TA1) | ~2 hours | SubQ | Thymic peptide | Published PK (Matteucci et al., 2017, PMID: 28057430) |
| LL-37 | Est. 30-60 minutes | SubQ / Topical | Cathelicidin | Estimated (susceptible to serum proteases) |
| Anti-Aging & Longevity | ||||
| Epitalon | Est. 2-3 hours | SubQ / IV | Tetrapeptide (Ala-Glu-Asp-Gly) | Estimated from Russian clinical studies (Khavinson) |
| MOTS-c | Est. 4-8 hours | SubQ | Mitochondrial-derived peptide | Estimated from animal PK data |
| NAD+ (IV infusion) | ~30-45 minutes (plasma) | IV | Coenzyme (not a peptide) | Published PK (limited human data) |
| Melanocortin Peptides | ||||
| Melanotan II | ~60 minutes | SubQ | MC1R/MC4R agonist | Published PK (Dorr et al., 1996, PMID: 8977815) |
| PT-141 (Bremelanotide) | ~120 minutes (2 hours) | SubQ | MC3R/MC4R agonist | Published PK (FDA label, 2019) |
| Metabolic & Other | ||||
| AOD-9604 | Est. 30-60 minutes | SubQ / Oral | GH fragment (176-191) | Estimated from Phase 2 studies |
| Oxytocin | ~3-5 minutes (IV) | IV / Intranasal | Nonapeptide hormone | Published PK (FDA label) |
| Insulin (regular) | ~5-8 minutes (IV) | SubQ / IV | 51-aa hormone | Published PK (FDA label) |
Key: “Est.” = estimated from animal data, detection windows, or community-reported values. Not from published human PK studies. “Published PK” = data from peer-reviewed human pharmacokinetic studies or FDA/EMA drug labels.
The DAC difference: why CJC-1295 spans minutes to days
The most dramatic half-life difference in this table is CJC-1295 without DAC (~30 minutes) versus CJC-1295 with DAC (~8 days). Same peptide, 384x difference in half-life. How?
DAC (Drug Affinity Complex) is a reactive chemical group that covalently binds to serum albumin after injection. Once bound, the CJC-1295 molecule rides along with albumin — which has its own half-life of ~19 days in humans. The peptide effectively borrows albumin’s longevity.
Teichman et al. (2006) demonstrated that a single subcutaneous dose of CJC-1295 DAC produced sustained GH elevation for 6-8 days, with IGF-1 remaining elevated for 9-11 days (PMID: 16352683). Without DAC, the same peptide is cleared in under an hour.
This is the same principle (albumin binding) that gives semaglutide and tirzepatide their long half-lives — they use fatty acid acylation instead of covalent DAC bonding, but the mechanism is similar: hitch a ride on albumin to extend circulation time. For a deeper dive into how these molecular modifications work, see our GLP-1 pharmacokinetics guide.
GLP-1 agonist half-lives: why they dominate
The three GLP-1 agonists at the top of the table (semaglutide, tirzepatide, retatrutide) have half-lives measured in days while most peptides are measured in minutes to hours. This is entirely due to engineering.
Native GLP-1 has a half-life of ~2 minutes — it’s rapidly degraded by DPP-4 enzymes. The research compounds achieve 5-7 day half-lives through two modifications: DPP-4-resistant amino acid substitutions (preventing enzymatic degradation) and fatty acid acylation that promotes albumin binding (preventing renal clearance).
For research protocol design, this means: semaglutide, tirzepatide, and retatrutide are truly once-weekly compounds. They reach steady state in 4-5 weeks. If you’re measuring acute pharmacological effects, you need to account for this long wash-in period. CertaPeptides carries all three — see semaglutide, tirzepatide, and retatrutide.
Short-acting peptides: why minutes doesn’t mean ineffective
BPC-157’s ~2-minute IV half-life seems absurdly short. But half-life and efficacy aren’t the same thing. BPC-157 works by triggering downstream signaling cascades — particularly involving NO system upregulation, VEGF expression, and FAK-paxillin pathway activation (Sikiric et al., 2016, PMID: 27306034). These effects persist long after the peptide itself is cleared.
Similarly, Selank and Semax have half-lives under 3 minutes in their native forms, yet their effects on BDNF and NGF expression persist for hours. The peptide is the trigger, not the sustained effector.
For research protocol design, this means short-acting peptides often benefit from more frequent dosing (1-3x daily) rather than weekly administration. Reconstituted solutions should be stored at 2-8°C and used within 28 days to maintain potency. Use our reconstitution calculator to work out concentrations, and check the peptide storage guide for detailed handling instructions.
How half-life affects storage stability
There’s a loose correlation between half-life and solution stability, but it’s not direct. Short half-life usually means the molecule is susceptible to enzymatic or chemical degradation — and those same vulnerabilities apply in the vial. Peptides with multiple basic residues (Arg, Lys) or free thiol groups (Cys) tend to degrade faster in solution.
General rules: lyophilized peptides at -20°C are stable for 6-24 months. Reconstituted peptides at 2-8°C last 21-28 days. Room temperature reconstituted peptides can lose significant activity within days. The shorter the half-life in vivo, the more critical proper storage becomes — because the same molecular vulnerabilities that cause rapid clearance also cause rapid degradation.
Frequently asked questions
What peptide has the longest half-life?
CJC-1295 with DAC at approximately 8 days, followed by semaglutide at ~7 days and cagrilintide at ~7 days. All three achieve long half-lives through albumin binding — DAC via covalent bonding, the others via fatty acid acylation. Without these modifications, native GLP-1 and native GHRH both have half-lives under 5 minutes.
Does half-life determine how often a peptide needs to be administered?
Half-life strongly influences dosing frequency but doesn’t exclusively determine it. Semaglutide (7-day half-life) is dosed weekly. BPC-157 (~2-minute half-life) is typically used 1-2x daily in research protocols despite rapid clearance — because its mechanism involves triggering downstream cascades rather than sustained receptor occupancy. The relationship between half-life and dosing depends on the mechanism of action.
Why is CJC-1295 DAC half-life so much longer than CJC-1295 without DAC?
The Drug Affinity Complex (DAC) covalently bonds to serum albumin after injection. Albumin has a ~19-day half-life in humans, so the peptide-albumin complex persists in circulation for days instead of minutes. Without DAC, CJC-1295 is a ~3 kDa peptide that’s rapidly cleared by the kidneys — below the ~60 kDa glomerular filtration threshold. With DAC, it becomes part of a ~70 kDa albumin complex that’s too large for renal clearance.
Limitations of this reference
- Many research peptides lack published human pharmacokinetic data. Values marked “Est.” are derived from animal studies or community reports and should be treated as approximations.
- Half-life varies by route of administration, individual metabolism, and co-administered compounds. Values shown are typical for the most common research route.
- This chart does not constitute dosing guidance. Research protocol design should reference primary literature for the specific compound and application.
References
- Lau J, et al. “Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide.” J Med Chem. 2015;58(18):7370-7380. PMID: 25943033
- Teichman SL, et al. “Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295.” JCEM. 2006;91(3):799-805. PMID: 16352683
- Raun K, et al. “Ipamorelin, the first selective growth hormone secretagogue.” Eur J Endocrinol. 1998;139(5):552-561. PMID: 9849822
- Nass R, et al. “Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults.” Ann Intern Med. 2008;149(9):601-611. PMID: 18981485
- Sikiric P, et al. “Brain-gut axis and pentadecapeptide BPC 157.” Curr Neuropharmacol. 2016;14(8):857-865. PMID: 27306034
- Dorr RT, et al. “Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.” Life Sci. 1996;58(20):1777-1784. PMID: 8977815
All compounds discussed are for laboratory and educational research purposes only. Not for human consumption.