Peptide Half-Life Chart: Quick Reference
Whether you're a clinician adjusting dosing schedules or a patient trying to understand why your medication requires daily versus weekly injections, half-life is the number that explains it all.
Whether you're a clinician adjusting dosing schedules or a patient trying to understand why your medication requires daily versus weekly injections, half-life is the number that explains it all. A peptide's half-life — the time it takes for half the active compound to be cleared from your bloodstream — determines how often it needs to be administered, how quickly it reaches steady state, and how long its effects persist after your last dose.
This quick-reference chart compiles half-life data for the most commonly discussed therapeutic and research peptides, organized by category. Where possible, values come from published pharmacokinetic studies and FDA prescribing information. For research peptides lacking formal clinical PK data, estimates are noted as such.
Table of Contents
- How to Read This Chart
- GLP-1 Receptor Agonists and Metabolic Peptides
- Growth Hormone Secretagogues and GHRH Analogs
- Healing and Repair Peptides
- Immune and Antimicrobial Peptides
- Neuropeptides and Nootropics
- Reproductive and Hormonal Peptides
- Endogenous Signaling Peptides
- Factors That Affect Peptide Half-Life
- Why Half-Life Matters Clinically
- FAQ
- The Bottom Line
- References
How to Read This Chart
Each entry includes:
- Half-life: The elimination half-life (t1/2) — time for plasma concentration to drop by 50%
- Route: Primary route of administration used in studies
- Steady state: Approximate time to reach stable plasma levels with regular dosing (generally 4-5 half-lives)
- Data quality: Whether values come from formal PK studies, FDA labeling, or preclinical/estimated data
A peptide with a 7-day half-life reaches steady state in about 4-5 weeks. One with a 2-hour half-life reaches steady state within 10 hours. This difference explains why semaglutide is dosed weekly while sermorelin requires daily injections.
For a deeper look at how half-life, bioavailability, and clearance interact, see our Peptide Pharmacokinetics Reference.
GLP-1 Receptor Agonists and Metabolic Peptides
These peptides target glucose metabolism, appetite, and body weight. The category spans three generations of drug development, and the progression from exenatide's 2.4-hour half-life to semaglutide's 7-day half-life tells the story of how peptide engineering has evolved.
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| Native GLP-1 | ~2 minutes | Endogenous | N/A | N/A | Clinical PK |
| Exenatide (Byetta) | 2.4 hours | SC | Twice daily | ~12 hours | FDA label |
| Exenatide ER (Bydureon) | ~2 weeks (depot) | SC | Weekly | ~6-7 weeks | FDA label |
| Liraglutide (Victoza/Saxenda) | 13 hours | SC | Once daily | ~3 days | FDA label |
| Dulaglutide (Trulicity) | ~5 days | SC | Weekly | ~2-4 weeks | FDA label |
| Semaglutide (Ozempic/Wegovy) | ~7 days (168 hrs) | SC | Weekly | ~4-5 weeks | FDA label |
| Oral semaglutide (Rybelsus) | ~7 days | Oral | Daily | ~4-5 weeks | FDA label |
| Tirzepatide (Mounjaro/Zepbound) | ~5 days (120 hrs) | SC | Weekly | ~4 weeks | FDA label |
| Pramlintide (Symlin) | ~48 minutes | SC | With meals | ~4 hours | FDA label |
| Amylin (native) | ~10-15 minutes | Endogenous | N/A | N/A | Clinical PK |
| Glucagon | 8-18 minutes | IV/IM/SC | As needed | N/A | FDA label |
Native GLP-1 lasts about 2 minutes in the bloodstream before dipeptidyl peptidase-4 (DPP-4) chews it apart. The entire history of GLP-1 drug development is an engineering effort to extend that number. Exenatide, derived from Gila monster saliva, resists DPP-4 but still clears in a few hours. Liraglutide added a fatty acid chain that binds albumin, pushing the half-life to 13 hours. Semaglutide refined this approach further — an amino acid substitution at position 8 blocks DPP-4, while a C-18 fatty diacid chain strengthens albumin binding, yielding a half-life of roughly one week (Pharmacokinetics and Clinical Implications of Semaglutide, 2018).
Growth Hormone Secretagogues and GHRH Analogs
These peptides stimulate the pituitary to release growth hormone. Their short half-lives are actually by design — GH release is pulsatile, and these peptides are meant to trigger a pulse, not maintain continuous stimulation.
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| Native GHRH | ~7-10 minutes | Endogenous | N/A | N/A | Clinical PK |
| Sermorelin | 11-12 minutes | SC/IV | Daily (bedtime) | ~1 hour | Clinical PK |
| Tesamorelin (Egrifta) | 26-38 minutes | SC | Daily | ~3 hours | FDA label |
| CJC-1295 without DAC (Mod GRF 1-29) | ~30 minutes | SC | Daily (often with GHRP) | ~2.5 hours | Preclinical/clinical est. |
| CJC-1295 with DAC | 5-8 days | SC | 1-2x weekly | ~3-5 weeks | Clinical PK |
| Ipamorelin | 2-3 hours | SC | Daily | ~12 hours | Preclinical est. |
| GHRP-6 | ~20-30 minutes | SC | 2-3x daily | ~2-3 hours | Preclinical est. |
| GHRP-2 | ~25-30 minutes | SC | 2-3x daily | ~2-3 hours | Preclinical est. |
| Hexarelin | ~55-70 minutes | SC | Daily | ~5-6 hours | Clinical PK |
| MK-677 (Ibutamoren) | 4-6 hours | Oral | Once daily | ~1 day | Clinical PK |
The contrast between CJC-1295 without DAC (~30 minutes) and CJC-1295 with DAC (5-8 days) is one of the most dramatic examples of half-life engineering in the peptide world. The Drug Affinity Complex (DAC) forms a covalent bond with albumin after injection, essentially hitching a ride on a molecule too large for the kidneys to filter. A single injection of CJC-1295 with DAC produced dose-dependent GH increases lasting 6+ days and IGF-1 elevations lasting 9-11 days (Teichman et al., JCEM, 2006).
MK-677 stands apart as the only oral compound in this group. It is not technically a peptide but a non-peptide GH secretagogue that activates the ghrelin receptor. Its 4-6 hour half-life with once-daily oral dosing makes it unique among GH-boosting compounds.
Healing and Repair Peptides
Research peptides studied for tissue repair and wound healing. Most lack formal human pharmacokinetic data, so values here are estimates drawn from animal studies and limited pilot trials.
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| BPC-157 | ~6-8 hours (est.) | SC/Oral | 1-2x daily | ~1-2 days | Preclinical est. |
| TB-500 (Thymosin Beta-4 fragment) | 2-3 hours (plasma) | SC | 1-2x weekly | ~12 hours | Preclinical est. |
| GHK-Cu | 0.5-2 hours | SC/Topical | Varies | ~5-10 hours | Preclinical est. |
| KPV | Not well characterized | SC/Topical | Varies | Unknown | Limited data |
BPC-157's estimated 6-8 hour half-life comes primarily from detection windows and animal pharmacology. No formal human PK study has been published with full half-life determination, though a 2025 pilot study involving intravenous infusion in two healthy adults confirmed the peptide is cleared relatively quickly without measurable effects on cardiac, hepatic, or renal biomarkers (Lee and Burgess, 2025).
GHK-Cu has a particularly short plasma half-life — some serum stability assays show degradation in under 30 minutes. But here's the thing: the tripeptide's biological effects persist well beyond its time in the bloodstream. GHK-Cu triggers gene expression changes in fibroblasts and other cells that continue for days after the peptide itself has been cleared. Plasma levels of GHK naturally decline with age, from roughly 200 ng/mL at age 20 to 80 ng/mL by age 60 (Pickart et al., BioMed Research International, 2015).
Immune and Antimicrobial Peptides
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| Thymosin Alpha-1 (Zadaxin) | ~2 hours | SC | 2x weekly (typical) | ~10 hours | Clinical PK |
| LL-37 | Short (minutes to hours) | Topical/local | Varies | Unknown | Limited data |
| Thymosin Beta-4 | ~2 hours (plasma) | SC | Varies | ~10 hours | Preclinical est. |
Thymosin Alpha-1 has the most robust pharmacokinetic data in this group. Despite a ~2-hour half-life, its immunomodulatory effects — including T-cell maturation and dendritic cell activation — persist well beyond the time the peptide circulates in plasma. This is why twice-weekly dosing is standard in the 35+ countries where thymalfasin is approved.
Neuropeptides and Nootropics
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| Semax | Minutes (intranasal) | Intranasal | 2-3x daily | ~minutes | Clinical est. (Russia) |
| Selank | Minutes (intranasal) | Intranasal | 2-3x daily | ~minutes | Clinical est. (Russia) |
| DSIP | ~8 minutes (IV) | IV/SC | Varies | ~40 minutes | Clinical PK |
| Dihexa | Not well characterized | Varies | Varies | Unknown | Preclinical only |
| Epitalon | Not well characterized | SC | Varies | Unknown | Limited data |
Both Semax and Selank have been registered pharmaceuticals in Russia for decades, but their pharmacokinetic profiles are characterized differently than Western drugs — much of the available data focuses on pharmacodynamic effects (how long cognitive or anxiolytic benefits last) rather than precise plasma half-life measurements. Intranasal delivery gets these small peptides past the blood-brain barrier quickly, but they're also cleared quickly.
Reproductive and Hormonal Peptides
| Peptide | Half-Life | Route | Dosing Frequency | Steady State | Data Source |
|---|---|---|---|---|---|
| Oxytocin | 3-5 minutes (IV) | IV/Intranasal | As needed | N/A | Clinical PK |
| Vasopressin (ADH) | 10-20 minutes | IV | Continuous or bolus | ~1-2 hours | Clinical PK |
| Desmopressin (DDAVP) | 1.5-2.5 hours | Intranasal/oral | 1-2x daily | ~12 hours | FDA label |
| PT-141 (Bremelanotide/Vyleesi) | 2.7 hours | SC | As needed (max 1x/day) | N/A (PRN) | FDA label |
| GnRH (native) | 2-4 minutes | Endogenous | N/A | N/A | Clinical PK |
| Gonadorelin | ~4 minutes (IV) | IV/SC | Pulsatile | Minutes | Clinical PK |
| Leuprolide (Lupron) | ~3 hours (SC solution) | SC/IM depot | Monthly to 6-monthly | Depot-dependent | FDA label |
| Goserelin (Zoladex) | 2-4 hours (SC solution) | SC implant | Monthly or 3-monthly | Implant-controlled | FDA label |
The GnRH analogs — leuprolide and goserelin — are fascinating case studies in drug formulation. The peptides themselves have half-lives of just a few hours, but depot formulations encapsulate them in biodegradable polymer microspheres that release the drug slowly over weeks or months. A single Lupron Depot injection can maintain therapeutic drug levels for up to six months.
Endogenous Signaling Peptides
These are naturally occurring peptides included for reference. Understanding their half-lives helps explain why synthetic analogs were developed.
| Peptide | Half-Life | Notes |
|---|---|---|
| Insulin (native) | ~5-6 minutes | Rapid clearance drives need for analogs |
| Somatostatin | ~1-3 minutes | Octreotide extends this to ~1.5 hours |
| Calcitonin | 10-60 minutes (route-dependent) | Salmon calcitonin has longer t1/2 than human |
| Substance P | ~1-2 minutes | Neuropeptide, rapidly degraded |
| Endogenous opioid peptides (enkephalins) | ~1-2 minutes | Extremely rapid enzymatic breakdown |
The pattern is clear: endogenous peptides are built for fast, local signaling and rapid clearance. Almost every therapeutic peptide drug represents an engineered solution to this built-in brevity.
Factors That Affect Peptide Half-Life
Half-life is not a fixed property of a molecule — it varies based on several factors.
Molecular Modifications
The biggest lever for extending peptide half-life is structural engineering:
- Fatty acid conjugation (acylation): Attaching a fatty acid chain enables albumin binding, shielding the peptide from renal filtration. This is how semaglutide achieves a 7-day half-life. The C-18 fatty diacid chain binds serum albumin with high affinity, and since albumin has a half-life of ~19 days, the peptide effectively borrows its longevity.
- PEGylation: Attaching polyethylene glycol chains increases molecular size above the kidney filtration threshold (~60 kDa) and shields against proteases.
- D-amino acid substitution: Replacing L-amino acids with their D-enantiomers renders peptide bonds invisible to most proteases. This is how octreotide's half-life was extended from somatostatin's 1-3 minutes to ~1.5 hours.
- Cyclization: Forming a circular peptide backbone eliminates exposed termini, reducing exopeptidase degradation.
- Depot formulations: Encapsulating peptides in biodegradable polymer microspheres (e.g., PLGA) creates slow-release formulations that can extend effective duration to months, regardless of the peptide's intrinsic half-life.
Route of Administration
The same peptide can have very different effective half-lives depending on how it's delivered:
- Intravenous: Fastest onset, shortest duration — the peptide enters circulation immediately and is subject to full first-pass clearance
- Subcutaneous: Slower absorption from the injection site creates a depot effect, often extending effective duration
- Intramuscular: Similar to subcutaneous but with slightly different absorption kinetics
- Intranasal: Rapid absorption, bypasses the blood-brain barrier for some peptides, but bioavailability can be variable
- Oral: Most peptides are destroyed in the GI tract; oral peptide delivery requires special formulations (e.g., SNAC technology for oral semaglutide)
For more on delivery methods, see our guide on peptide bioavailability and routes of administration.
Patient-Specific Variables
- Renal function: Peptides under ~60 kDa are filtered by the kidneys. Reduced kidney function can significantly extend half-life — goserelin's half-life nearly triples in severe renal impairment (4.2 hours to 12.1 hours).
- Body weight: Larger distribution volumes in heavier individuals can affect both peak concentrations and clearance rates.
- Age: Proteolytic enzyme activity and organ function change with age, altering clearance.
- Injection site: Subcutaneous blood flow varies by anatomical location (abdomen vs. thigh vs. arm), which affects absorption rate.
Why Half-Life Matters Clinically
Dosing Frequency
The most direct clinical consequence: shorter half-life means more frequent dosing. Exenatide's 2.4-hour half-life requires twice-daily injections. Semaglutide's 7-day half-life allows weekly dosing. Patient adherence data consistently shows that less frequent dosing improves compliance — one reason the field has moved toward longer-acting formulations.
Time to Steady State
Steady state takes approximately 4-5 half-lives. For semaglutide (t1/2 = 7 days), that's 4-5 weeks before plasma levels stabilize. This explains why clinicians start patients on lower doses and titrate upward over months — the drug is still accumulating during those early weeks.
Washout Period
When stopping a peptide, it takes 4-5 half-lives for the drug to clear to negligible levels. For semaglutide, that means the drug persists in your system for roughly 5-7 weeks after your last injection. For exenatide, it's gone in about 12 hours. This matters for managing side effects, planning surgeries (GLP-1 agonists can cause aspiration risk under anesthesia due to delayed gastric emptying), and understanding the timeline for return of appetite after stopping weight-loss medications.
Drug Interactions
Long-acting GLP-1 agonists delay gastric emptying, which can slow the absorption of oral medications taken at the same time. The magnitude of this effect is partly related to how long the peptide maintains therapeutic levels between doses. For more on this, see our guide on how GLP-1 medications work.
FAQ
What does "half-life" actually mean for peptides?
Half-life (t1/2) is the time it takes for the concentration of a peptide in your blood plasma to decrease by 50%. If a peptide has a 6-hour half-life, then 6 hours after injection, half the dose remains in your bloodstream. After another 6 hours (12 hours total), one quarter remains. After 5 half-lives, less than 3% of the original dose is left. This pharmacokinetic property determines how often a peptide needs to be administered to maintain therapeutic levels.
Why do some peptides have such short half-lives?
Natural peptides are designed for fast signaling. Your body produces them in bursts, they deliver a signal to nearby cells, and then enzymes (particularly DPP-4, neprilysin, and various endopeptidases) break them down within minutes. This tight regulation prevents over-stimulation. The kidney also rapidly filters small peptides (under ~6 kDa). Therapeutic peptide development is largely about overcoming these natural clearance mechanisms.
Does a longer half-life mean a peptide is more effective?
Not necessarily. Half-life determines dosing convenience, not potency. Sermorelin has an 11-minute half-life but produces a meaningful GH pulse that lasts hours. What matters is whether the peptide reaches therapeutic concentrations at its target for long enough to produce the desired biological effect. That said, longer half-lives generally improve patient adherence because they allow less frequent dosing.
How is peptide half-life measured?
Researchers administer a known dose (usually intravenously for the most accurate measurement), then draw blood samples at multiple time points and measure peptide concentration using assays like ELISA or LC-MS/MS. They plot concentration versus time on a logarithmic scale and calculate the slope of the terminal elimination phase. For peptides with very short half-lives (minutes), sampling must be extremely frequent and begin immediately after administration.
Why are half-life values for research peptides often listed as estimates?
Formal pharmacokinetic studies require FDA-regulated clinical trials with standardized protocols, validated assays, and adequate sample sizes. Many research peptides (BPC-157, TB-500, Epitalon, etc.) have never undergone such studies in humans. Available half-life estimates often come from animal models, in vitro serum stability assays, or extrapolation from detection windows. These estimates are useful but should be understood as approximate.
Can I extend a peptide's effects by taking a larger dose?
Taking more doesn't proportionally extend duration. Because elimination is usually first-order (a constant fraction is removed per unit time, not a constant amount), doubling the dose adds only one additional half-life of duration. It does, however, increase peak concentration, which may raise the risk of side effects without proportionally increasing benefit.
The Bottom Line
Peptide half-life is the single most important pharmacokinetic parameter for understanding dosing schedules, onset of action, and duration of effect. The field has evolved from the 2-minute half-life of native GLP-1 to engineered analogs that persist for a week — a 5,000-fold improvement achieved through fatty acid conjugation, D-amino acid substitution, cyclization, and depot formulations.
For FDA-approved peptide drugs, half-life values are well established through rigorous PK studies. For research peptides, many published values are estimates from preclinical data. When evaluating any peptide's half-life, consider the data source, the route of administration studied, and whether the number reflects plasma clearance or biological activity duration — these can be very different.
The most important takeaway: always discuss dosing timing with your healthcare provider. Half-life charts are reference tools, not prescribing guides. Individual factors — kidney function, body composition, co-medications, and injection technique — all affect how a given peptide behaves in your body.
References
- Raghava GPS, et al. "PEPlife: A Repository of the Half-life of Peptides." Scientific Reports. 2016;6:36617. PMC5098197
- Cavaco M, et al. "Estimating peptide half-life in serum from tunable, sequence-related physicochemical properties." Clinical and Translational Science. 2021;14(4):1349-1358. PMC8301568
- "Systemic Pharmacokinetic Principles of Therapeutic Peptides." Clinical Pharmacokinetics. 2025. Springer Nature
- Lau J, et al. "Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide." Journal of Medicinal Chemistry. 2015;58(18):7370-7380.
- Teichman SL, et al. "Prolonged stimulation of growth hormone and insulin-like growth factor I secretion by CJC-1295." JCEM. 2006;91(3):799-805. PubMed 16352683
- Pickart L, et al. "GHK and DNA: Resetting the Human Genome to Health." BioMed Research International. 2014. PMC4180391
- Lee TT, Burgess DJ. "Safety of Intravenous Infusion of BPC157 in Humans: A Pilot Study." 2025. PubMed 40131143
- FDA Prescribing Information for Ozempic (semaglutide), Mounjaro (tirzepatide), Victoza (liraglutide), Byetta (exenatide), Egrifta (tesamorelin), Vyleesi (bremelanotide). FDA.gov
- Tesamorelin Drug Information. LiverTox, NCBI Bookshelf. NBK548730
- Ishida J, et al. "Growth hormone secretagogues: history, mechanism of action, and clinical development." JCSM Rapid Communications. 2020;3(1):25-37. Wiley Online