Guide

Peptide Half-Life Reference Table

Half-life — the time required for plasma concentration of a substance to decrease by 50% — is the single most important pharmacokinetic parameter for understanding how a peptide behaves after administration. It determines how long a compound remains active, how frequently it must be given to maintain steady levels, and how quickly it clears from the body. This reference table compiles approximate half-life values for all 32 compounds tracked on this site, organized by functional category. The values are drawn from FDA prescribing labels, peer-reviewed pharmacokinetic studies, and published clinical trial data. For many research peptides, formal pharmacokinetic characterization in humans is absent; those entries note the evidence gap explicitly. This page is a pharmacokinetic reference, not dosing guidance. Half-lives can vary by formulation, route of administration, individual metabolism, assay method, and study design. Always consult the primary sources for context.

How to Read This Table

The half-life values below are approximate ranges drawn from published literature. A single half-life number rarely tells the full story: many peptides exhibit multi-compartment pharmacokinetics with distribution and elimination phases, and some have nonlinear or dose-dependent clearance. Source quality is indicated for each entry. 'FDA label' means the value is from an approved prescribing label. 'Peer-reviewed PK study' means the value comes from a published human pharmacokinetic study. 'Preclinical only' means human half-life has not been formally characterized and the value is estimated from animal data or analog inference. 'Not well characterized' means no reliable human pharmacokinetic data exists. Route refers to the route used in the cited study or label, not a recommendation. Many peptides listed here are not FDA-approved and are sold only as research-use-only reagents.

Key points

• Half-life is the time for plasma concentration to decrease by 50%. It governs dosing frequency but is not the same as duration of effect — some peptides have downstream effects that outlast their plasma presence.
• Values marked 'FDA label' are from approved prescribing information and represent the highest source quality. Values from 'Peer-reviewed PK study' are from published human pharmacokinetic trials.
• Entries marked 'Not well characterized' or 'Preclinical only' lack formal human pharmacokinetic data. Any stated half-life for these compounds is an estimate and should be treated with caution.
• Route matters: a peptide administered intravenously, subcutaneously, intranasally, or orally can have substantially different apparent half-lives. The route listed is the one used in the cited source.
• This table does not provide dosing instructions. Half-life is a pharmacokinetic property; dosing frequency depends on therapeutic target, desired trough levels, safety margins, and clinical context.
• Half-lives can differ between healthy volunteers and patient populations, between formulations (e.g., immediate vs. extended release), and between assay methods.

GLP-1 and Multi-Incretin Receptor Agonists

This category includes the GLP-1 receptor agonists and the newer multi-incretin agonists (dual and triple receptor). These compounds are engineered for extended half-lives through amino acid modifications, fatty acid conjugation, and albumin binding, enabling once-weekly dosing for the longest-acting members. Native GLP-1 has a half-life of approximately 2 minutes due to rapid DPP-4 degradation; pharmaceutical GLP-1 agonists extend this by 80-fold or more.

Key points

• Semaglutide — Approximate half-life: ~165 hours (~7 days). Route: Subcutaneous (also available as oral formulation with lower bioavailability). Source quality: FDA label (Ozempic, Wegovy, Rybelsus). The extended half-life is achieved via amino acid modifications and albumin binding, enabling once-weekly subcutaneous dosing.
• Tirzepatide — Approximate half-life: ~120 hours (~5 days). Route: Subcutaneous. Source quality: FDA label (Mounjaro, Zepbound). Dual GIP/GLP-1 receptor agonist. The ~5-day half-life supports once-weekly dosing.
• Retatrutide — Approximate half-life: ~157 hours (~6.5 days). Route: Subcutaneous. Source quality: Peer-reviewed Phase 2 study (investigational). Retatrutide is a triple GLP-1/GIP/glucagon receptor agonist. It is investigational only — not FDA-approved for any indication. Half-life data is from the Phase 2 trial (Jastreboff et al., NEJM 2023).

Growth Hormone Releasing Hormone (GHRH) and Growth Hormone Secretagogue (GHRP) Peptides

This category includes GHRH analogs (tesamorelin, sermorelin, CJC-1295) and growth hormone secretagogues (ipamorelin, MK-677). GHRH analogs act on GHRH receptors at the pituitary; GHRPs and MK-677 act on the ghrelin (growth hormone secretagogue) receptor. These two pathways are pharmacologically distinct and can have additive effects. Half-lives in this category vary dramatically — from approximately 30 minutes for unmodified GHRH analogs to 8 days for CJC-1295 with the Drug Affinity Complex (DAC) modification.

Key points

• CJC-1295 with DAC — Approximate half-life: ~8 days (~192 hours). Route: Subcutaneous (research). Source quality: Peer-reviewed PK study (Teichman et al., JCEM 2006). The DAC modification binds serum albumin, dramatically extending half-life. IGF-1 elevation was observed for up to 6 days after a single dose.
• CJC-1295 without DAC — Approximate half-life: ~30 minutes. Route: Subcutaneous (research). Source quality: Peer-reviewed PK study. Without the DAC (Drug Affinity Complex) albumin-binding moiety, CJC-1295 behaves as a short-acting GHRH analog with a half-life comparable to tesamorelin and sermorelin.
• Tesamorelin — Approximate half-life: ~26 minutes. Route: Subcutaneous. Source quality: FDA label (Egrifta). FDA-approved for HIV-associated lipodystrophy. The short half-life requires daily administration. The pharmacodynamic effect (GH/IGF-1 elevation) outlasts the plasma half-life.
• Sermorelin — Approximate half-life: ~11–16 minutes. Route: Subcutaneous (diagnostic/investigational). Source quality: Peer-reviewed literature (formerly FDA-approved as Geref, now discontinued). Very short half-life consistent with native GHRH degradation by DPP-4 and other peptidases.
• Ipamorelin — Approximate half-life: ~2 hours. Route: Subcutaneous (research). Source quality: Peer-reviewed pharmacology (Raun et al., 1998). Ipamorelin is a pentapeptide GHRP acting on the ghrelin receptor with selectivity for GH over cortisol and prolactin. No FDA approval for any indication. Human PK data is limited.
• MK-677 (Ibutamoren) — Approximate half-life: ~24 hours. Route: Oral. Source quality: Peer-reviewed PK study (Svensson et al., JCEM 2000). MK-677 is a non-peptide oral ghrelin receptor agonist. The ~24-hour half-life supports once-daily oral dosing. Not FDA-approved for any indication.

Recovery and Tissue Repair Peptides

This category includes BPC-157 and TB-500 (thymosin beta-4), which are widely discussed in community contexts for injury recovery and tissue repair. A major limitation for both is the near-total absence of formal human pharmacokinetic data. Neither compound is FDA-approved, and published half-life values are not reliably established from human studies.

Key points

• BPC-157 — Half-life: Not well characterized in humans. No published human pharmacokinetic study has established a formal plasma half-life. Route: Various (subcutaneous, oral — research only). Source quality: Preclinical only. BPC-157 has been studied in animal models of wound healing and tissue repair, but no human PK trials have been published. Any circulating half-life values are estimates extrapolated from animal data or analog reasoning.
• TB-500 (Thymosin beta-4) — Half-life: Not well characterized in humans. Route: Subcutaneous (research). Source quality: Preclinical only. Thymosin beta-4 occurs endogenously; the synthetic fragment TB-500 has been studied in animal models (cardiac repair, wound healing). No reliable human pharmacokinetic half-life has been published. Values cited in community sources are not from peer-reviewed human PK studies.

Cognitive and Nootropic Peptides

This category includes peptides and peptide-derived nootropics studied for cognitive enhancement, neuroprotection, or attention. Many of these compounds (Semax, Selank, Noopept) were developed in Russia and have published clinical data primarily from Russian institutions, often without independent Western replication. Cerebrolysin is a porcine brain-derived peptide preparation with published European clinical trial data. Dihexa is a preclinical angiotensin IV analog with no human pharmacokinetic data. Half-life values for several of these compounds are estimated or derived from limited studies.

Key points

• Semax — Approximate half-life: Several hours (not precisely characterized in humans). Route: Intranasal. Source quality: Peer-reviewed (Russian clinical studies). Semax is a heptapeptide ACTH(4-10) analog. Intranasal administration is used in Russian clinical practice. Precise human pharmacokinetic half-life is not well established in Western literature.
• Selank — Approximate half-life: Several hours (not precisely characterized in humans). Route: Intranasal. Source quality: Peer-reviewed (Russian studies). Selank is a synthetic heptapeptide tuftsin analog. Published pharmacological studies are primarily from Russian research groups. Human PK half-life is not well established.
• Noopept — Approximate half-life: Several hours (metabolized to active cycloprolylglycine). Route: Oral. Source quality: Peer-reviewed (Russian clinical studies). Noopept (N-phenylacetyl-L-prolylglycine ethyl ester) is a dipeptide nootropic. It is rapidly absorbed and metabolized; the parent compound has a short plasma half-life, but the active metabolite (cycloprolylglycine) persists longer.
• Cerebrolysin — Half-life: Not well characterized as a single value (complex peptide mixture). Route: Intravenous or intramuscular. Source quality: Peer-reviewed (Cochrane review, European trials). Cerebrolysin is a porcine brain-derived peptide preparation containing multiple neurotrophic peptides. As a mixture, it does not have a single defined half-life; individual component half-lives vary.
• Dihexa — Half-life: Not well characterized in humans. Route: Research (various). Source quality: Preclinical only. Dihexa is an angiotensin IV analog developed at Washington State University. All published data is from preclinical (rat/mouse) models. No human pharmacokinetic study has been published.
• Methylene Blue — Approximate half-life: ~5–6 hours (as drug). Route: Intravenous (FDA-approved as Provayblue); oral (research). Source quality: FDA label (Provayblue) and peer-reviewed. Methylene blue is a small molecule, not a peptide, but is tracked here due to its nootropic community use. Half-life is approximately 5–6 hours with urinary excretion.
• 5-Amino-1MQ — Half-life: Not well characterized in humans. Route: Research (various). Source quality: Preclinical only. 5-Amino-1MQ is a small-molecule NNMT inhibitor. Published pharmacokinetic data is from animal studies. No human PK study has been published.

Cosmetic and Skin Peptides

This category includes peptides used in cosmetic and skincare applications. Topically applied peptides face the barrier of the stratum corneum, and systemic half-life is generally not the relevant pharmacokinetic measure — skin residence time and local tissue concentration matter more. GHK-Cu is a naturally occurring copper peptide studied for wound healing and skin repair. Argireline and Matrixyl are cosmetic peptides used in topical anti-aging products with no meaningful systemic pharmacokinetic data.

Key points

• GHK-Cu — Half-life: Not well characterized for systemic pharmacokinetics (topical application). Route: Topical (cosmetic research). Source quality: Peer-reviewed (Pickart et al., in vitro and cosmetic studies). GHK-Cu (glycyl-L-histidyl-L-lysine copper complex) occurs endogenously. Topical skin residence time is the relevant measure, not plasma half-life. Published studies focus on in vitro activity and cosmetic outcomes.
• Argireline (Acetyl Hexapeptide-8) — Half-life: Not applicable (topical cosmetic). Route: Topical. Source quality: Peer-reviewed (clinical cosmetic study, Wang et al. 2013). Argireline is a hexapeptide marketed as a topical wrinkle-reducing agent. No systemic pharmacokinetic data exists; the compound is applied topically and acts locally.
• Matrixyl (Palmitoyl Pentapeptide-4) — Half-life: Not applicable (topical cosmetic). Route: Topical. Source quality: Peer-reviewed (Robinson et al. 2005; permeation studies). Matrixyl is a palmitoylated pentapeptide used in anti-aging skincare. Skin permeation studies exist (Biomol Ther 2014) but systemic pharmacokinetic half-life is not a relevant measure.
• AOD-9604 — Half-life: Not well characterized in humans (Phase 2 discontinued). Route: Subcutaneous or oral (research). Source quality: Peer-reviewed (Phase 2 trial, ClinicalTrials.gov). AOD-9604 is a C-terminal fragment of human growth hormone (hGH 177-191). Phase 2 obesity trials did not meet primary endpoints. Human pharmacokinetic half-life is not well established in published literature.

Immune and Antimicrobial Peptides

This category includes peptides with immune-modulating or antimicrobial properties. Thymosin Alpha-1 is approved in over 30 countries (as Zadaxin) for hepatitis and immune adjuvant use, though not FDA-approved in the United States. LL-37 is the sole human cathelicidin antimicrobial peptide. KPV is an anti-inflammatory tripeptide derived from alpha-MSH with only preclinical data. Human pharmacokinetic data varies widely across this category.

Key points

• Thymosin Alpha-1 — Approximate half-life: ~2 hours (alpha phase), with a longer terminal phase. Route: Subcutaneous. Source quality: Peer-reviewed (King & Tuthill, 2016; Zadaxin product information). Approved in 30+ countries as Zadaxin. Not FDA-approved in the US. Published pharmacokinetic data comes from international clinical use.
• LL-37 — Half-life: Not well characterized for therapeutic use. Route: Research (various). Source quality: Peer-reviewed (Dürr et al., 2006; Kahlenberg & Kaplan, 2013). LL-37 is the sole human cathelicidin antimicrobial peptide. No FDA-approved therapeutic formulation. Limited clinical trial data. Pharmacokinetic half-life in humans is not established.
• KPV — Half-life: Not well characterized in humans. Route: Research (various). Source quality: Preclinical only. KPV (Lys-Pro-Val) is a tripeptide derived from alpha-MSH with anti-inflammatory activity in preclinical models. No human clinical trials have been published. No human pharmacokinetic data exists.

Longevity, Metabolic, and Mitochondrial Compounds

This category includes compounds studied for longevity, metabolic health, and mitochondrial function. Most are small molecules or supplements rather than peptides, but are tracked on this site due to their overlap with the peptide research community. Pharmacokinetic data quality varies: metformin and rapamycin have well-established half-lives from FDA labels and decades of clinical use, while MOTS-c, Epitalon, and DSIP have limited or no reliable human pharmacokinetic data.

Key points

• Rapamycin (Sirolimus) — Approximate half-life: ~62 hours (oral). Route: Oral. Source quality: FDA label (Rapamune). Rapamycin is a small molecule mTOR inhibitor, FDA-approved for organ rejection prophylaxis and LAM. The long half-life means steady-state is reached after approximately 2 weeks of daily dosing. Tracked in longevity research due to ITP lifespan data in mice.
• Metformin — Approximate half-life: ~6 hours (immediate release). Route: Oral. Source quality: FDA label (Glucophage). Metformin is a small molecule AMPK activator, FDA-approved for Type 2 diabetes. Tracked in longevity research due to the TAME trial and observational mortality data. Extended-release formulations have different pharmacokinetics.
• NAD+ / NMN / NR — Approximate half-life: NAD+ cellular half-life ~1–2 hours; precursor pharmacokinetics vary. Route: Oral (supplement). Source quality: Peer-reviewed (Yoshino et al. 2021; Dollerup et al. 2018; FDA GRAS for NR). NMN was excluded from DSHEA by the FDA in 2022. NR has GRAS status. Plasma half-life of precursors is short, but cellular NAD+ elevation can persist longer.
• Spermidine — Approximate half-life: Not well characterized as a supplement (endogenous polyamine). Route: Oral (supplement). Source quality: Peer-reviewed (Schwarz et al., JAMA Netw Open 2022; Hofer et al., Nat Aging 2022). Spermidine is a naturally occurring polyamine. Published human supplementation studies measure cognitive and biomarker outcomes but do not report formal plasma half-life.
• Fisetin — Approximate half-life: ~1–3 hours (oral, based on limited PK data). Route: Oral. Source quality: Peer-reviewed (senolytic trials; TROFFi study). Fisetin is a flavonoid senolytic compound. Human pharmacokinetic data is limited; published studies report rapid metabolism and short plasma half-life.
• MOTS-c — Half-life: Not well characterized in humans. Route: Research (various). Source quality: Preclinical only (Lee et al., Cell Metabolism 2015). MOTS-c is a mitochondrial-derived peptide. Published data is primarily preclinical. No interventional human trials with pharmacokinetic endpoints have been published.
• Epitalon — Half-life: Not well characterized in humans. Route: Subcutaneous or intranasal (research). Source quality: Peer-reviewed (Khavinson et al.; Russian studies). Epitalon (Ala-Glu-Asp-Gly) is a tetrapeptide studied for telomerase activation. Published research is primarily from a single Russian research group without independent Western replication. No human pharmacokinetic half-life has been established.
• DSIP (Delta Sleep-Inducing Peptide) — Half-life: Not well characterized in humans (clinical literature is old and inconclusive). Route: Various (research). Source quality: Peer-reviewed (1970s–1980s clinical studies). DSIP is a nonapeptide isolated from rabbit brain extract. Early clinical studies showed mixed and inconclusive sleep effects. Modern pharmacokinetic data is absent.

Methodological Notes and Evidence Gaps

The half-life values in this table come from heterogeneous source types: FDA prescribing labels (the highest quality), peer-reviewed human pharmacokinetic studies, preclinical animal studies, and — for some entries — no reliable published data at all. Understanding these source quality differences is essential for interpreting the values correctly. Several recurring evidence gaps are worth noting.

Key points

• FDA-approved drugs (semaglutide, tirzepatide, tesamorelin, rapamycin, metformin, methylene blue) have the most reliable half-life data from regulatory pharmacokinetic studies. These values are from controlled trials with validated bioanalytical methods.
• Investigational compounds (retatrutide) have Phase 2 pharmacokinetic data from peer-reviewed studies but no FDA label. Values may be refined as Phase 3 data emerges.
• Research peptides with published human pharmacology studies (CJC-1295, ipamorelin, MK-677, sermorelin, thymosin alpha-1) have partial pharmacokinetic data, often from small single-dose studies in healthy volunteers. These values are reasonable approximations but come from limited sample sizes.
• Compounds developed primarily in Russian institutions (Semax, Selank, Noopept, DSIP, Epitalon) have published clinical data that often lacks formal pharmacokinetic characterization or independent Western replication. Half-life values for these are approximate and based on limited studies.
• Research peptides without published human pharmacokinetic data (BPC-157, TB-500, GHK-Cu, KPV, Dihexa, MOTS-c, 5-Amino-1MQ) are marked 'Not well characterized' or 'Preclinical only.' Any half-life values circulating in community sources for these compounds are not from peer-reviewed human PK studies.
• Topical cosmetic peptides (Argireline, Matrixyl, GHK-Cu) do not have meaningful systemic half-lives because they are applied to skin and act locally. Skin permeation and local tissue residence are the relevant measures, not plasma concentration.
• Cerebrolysin is a complex peptide mixture and does not have a single defined half-life. Individual component half-lives vary, and the therapeutic effect is attributed to the cumulative neurotrophic activity of multiple peptides.

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