Understanding the half-life of a peptide compound is one of the most critical variables in designing an effective research research notes. Half-life — or t½ — determines how long a peptide remains at pharmacologically active levels in the body before half of it is eliminated. This directly influences dosing frequency, peak-to-trough variability, and the overall stability of your research results.
For researchers working with compounds like BPC-157, TB-500, semaglutide, ipamorelin, PT-141, and dozens of others, an accurate understanding of half-life is not optional — it's foundational. Whether you're using PepSync for precision dosing calculations or tracking injection timing with our visual syringe display, knowing when each peptide peaks and declines is essential.
In this comprehensive reference guide, we break down the half-life data for the most commonly researched peptide compounds — including both endogenous peptides and newer analogs — and explain what those numbers mean for a research research notes design, reconstitution strategy, and injection timing.
What Is Peptide Half-Life?
Half-life (t½) is the time required for the concentration or activity of a peptide to decrease by 50% in the body. For example, if a peptide has a half-life of 12 hours, then 12 hours after administration, half of the original dose remains active in the system. Another 12 hours later, only 25% remains, and so on.
It's important to distinguish between plasma half-life (how long the peptide circulates in the bloodstream) and biological half-life (how long the peptide exerts its intended effect). In practice, these values are often used interchangeably in research settings, though they can diverge for certain compounds.
Factors that influence peptide half-life include:
- Molecular weight and structure — Larger, more complex peptides typically degrade more slowly
- Route of administration — Subcutaneous (SC), intramuscular (IM), and intranasal (IN) all produce different absorption and elimination profiles
- Sequence modifications — D-amino acid substitutions, acetylation, PEGylation, and fatty acid conjugation can dramatically extend half-life
- Individual metabolism — Enzymatic degradation rates (e.g., by peptidases in blood and tissues) vary between individuals
- Protein binding — Peptides that bind to albumin or other carrier proteins tend to have longer half-lights
Peptide Half-Life Reference Chart
The following reference chart covers the most commonly researched peptide compounds. All half-life values represent typical ranges observed in research literature and are provided for informational purposes. Actual values may vary based on dose, route of administration, and individual physiology.
Repair and Growth Peptides
BPC-157 (Body Peptide Compound-157)
Half-life: ~4–12 hours
BPC-157 is one of the most widely studied body-peptide compounds in research. Its relatively short half-life means it requires frequent dosing to maintain consistent research levels. BPC-157 is typically dosed 1–2 times daily in research research notes. For detailed reconstitution guidance, see our BPC-157 reconstitution guide.
TB-500 (Thymosin Beta-4 Fragment)
Half-life: ~6–24 hours
TB-500 is a synthetic fragment of the naturally occurring protein thymosin beta-4. Research suggests its half-life is longer than BPC-157, though it still research considerations from regular dosing. Many researchers choose to record TB-500 once or twice daily. See our TB-500 peptide guide for full details.
KPV (Lys-Pro-Arg)
Half-life: ~30 minutes – 2 hours
KPV is the C-terminal tripeptide fragment of alpha-melanocyte-stimulating hormone (α-MSH). Its extremely short half-life is one of the reasons it's often dosed multiple times per day in research. It is typically used in anti-inflammatory research contexts.
GHK-Cu (Copper Tripeptide-1)
Half-life: ~2–4 hours
GHK-Cu is a naturally occurring copper-binding tripeptide used extensively in skin and tissue regeneration research. Its relatively short half-life is offset by its low molecular weight and high bioavailability.
Secretagogues (Growth Hormone Releasers)
Ipamorelin
Half-life: ~1–2 hours
Ipamorelin is one of the most popular growth hormone secretagogues in research. Its short half-life typically requires once- or twice-daily dosing — often recorded in the morning and/or before bed to mimic natural GH pulse patterns.
Sermorelin
Half-life: ~2 hours
Sermorelin is a 29-amino-acid fragment of human growth hormone-releasing hormone (GHRH). It has a longer half-life than many other GHRH analogs and is typically dosed once or twice daily in research settings.
Hexarelin
Half-life: ~30–60 minutes
Hexarelin is a potent hexapeptide GH secretagogue with a very short half-life, making multiple daily doses common in research research notes.
Ipamorelin + CJC-1295 (No DAC) Stack
Combined half-life: ~1–2 hours (ipamorelin-dominant)
When ipamorelin is combined with CJC-1295 (no drug affinity complex), the CJC-1295 extends the overall duration of elevated GH levels. CJC-1295 (no DAC) itself has a half-life of approximately 6 hours, but ipamorelin remains the rate-limiting factor.
GLP-1 Receptor Agonists
Semaglutide
Half-life: ~1 week (168 hours)
Semaglutide is one of the longest-acting peptides in current research use. Its half-life of approximately 7 days is due to albumin binding and a single reversible amino acid substitution (lysine to fatty acid chain). This allows for once-weekly dosing in research research notes. See our semaglutide reconstitution guide for detailed instructions.
Retatrutide
Half-life: ~4–5 days
Retatrutide is a triple agonist (GLP-1, GIP, and glucagon) currently in advanced clinical research. Its half-life of roughly 4–5 days supports once-weekly or even twice-weekly dosing in some research research notes.
Exenatide
Half-life: ~2.4 hours
Exenatide (Byetta) is a shorter-acting GLP-1 analog with a half-life of approximately 2.4 hours. It typically requires twice-daily dosing in research settings. The extended-release formulation (Bydureon) has a different release profile.
Liraglutide
Half-life: ~13 hours
Liraglutide has a significantly longer half-life than exenatide due to a fatty acid side chain that promotes albumin binding. This allows for once-daily dosing in most research research notes.
Erectile Function and Vasodilators
PT-141 (Bremelanotide)
Half-life: ~1–2 hours
PT-141 is a melanocortin receptor agonist used in research for its effects on sexual function. Despite its short half-life, its effects can last several hours due to downstream signaling cascades. It is typically recorded 1–2 hours before the desired effect.
SS-31 (Elamipretide)
Half-life: ~1–2 hours
SS-31 is a mitochondria-targeting tetrapeptide used in cellular energy and aging research. Its relatively short half-life is well-characterized in preclinical models.
Other Notable Peptides
CJC-1295 (No DAC)
Half-life: ~6 hours
When used alone (not conjugated with a drug affinity complex), CJC-1295 has a half-life of approximately 6 hours. It is frequently stacked with GH secretagogues like ipamorelin.
CJC-1295 (with DAC)
Half-life: ~6–7 days
The DAC (drug affinity complex) version of CJC-1295 dramatically extends its half-life through reversible albumin binding, allowing for once-weekly or less frequent dosing.
GHK (without copper)
Half-life: ~2–4 hours
The copper-free form of GHK follows a similar elimination profile to GHK-Cu.
Thymosin Alpha-1
Half-life: ~2–4 hours
Thymosin Alpha-1 is a 28-amino-acid peptide used in immune modulation research. Its half-life is moderate, and it is typically dosed once or twice daily.
LL-37
Half-life: ~1–3 hours
LL-37 is a human cathelicidin antimicrobial peptide with a relatively short half-life in research models.
AOD-9604
Half-life: ~6–8 hours
AOD-9604 is a modified fragment of human growth hormone (amino acids 177–191) used in body composition research. Its half-life is moderate, supporting once- or twice-daily dosing.
Fragment 176–191 of hGH
Half-life: ~6–8 hours
This is the original fragment from which AOD-9604 was derived. It shares a similar half-life profile.
PT-141 (Bremelanotide)
Half-life: ~1–2 hours
PT-141 is a melanocortin receptor agonist used in research for its effects on sexual function. Despite its short half-life, its effects can last several hours due to downstream signaling cascades. It is typically recorded 1–2 hours before the desired effect.
SS-31 (Elamipretide)
Half-life: ~1– ~2 hours
SS-31 is a mitochondria-targeting tetrapeptide used in cellular energy and aging research. Its relatively short half-life is well-characterized in preclinical models.
Extended Half-Life Peptides
Long-Acting Growth Hormone (Pegvisomant)
Half-life: ~6 hours (but prolonged effect)
Pegylated versions of various peptides can achieve half-lives of several days to weeks. Pegylation is one of the most common strategies for extending peptide half-life in research.
GHRP-6
Half-life: ~30–60 minutes
GHRP-6 is a hexapeptide growth hormone secretagogue with a very short half-life. It is typically dosed 2–3 times daily in research research notes.
Quick-Reference Summary Table
- Semaglutide — ~168 hours (7 days)
- CJC-1295 (with DAC) — ~6–7 days
- Retatrutide — ~4–5 days
- BPC-157 — ~4–12 hours
- TB-500 — ~6–24 hours
- Liraglutide — ~13 hours
- AOD-9604 — ~6–8 hours
- CJC-1295 (no DAC) — ~6 hours
- Sermorelin — ~2 hours
- GHK-Cu — ~2–4 hours
- Thymosin Alpha-1 — ~2–4 hours
- Ipamorelin — ~1–2 hours
- PT-141 — ~1–2 hours
- GHK (no copper) — ~2–4 hours
- Hexarelin — ~30–60 minutes
- KPV — ~30 min – 2 hours
- GHRP-6 — ~30–60 minutes
- Exenatide — ~2.4 hours
- LL-37 — ~1–3 hours
- SS-31 — ~1–2 hours
Why Half-Life Matters for Your Research research notes
Knowing the half-life of each peptide you work with directly informs several critical aspects of a research research notes:
Dosing Frequency
Shorter half-life peptides (e.g., GHRP-6, Ipamorelin) require more frequent administration to maintain stable blood levels. Longer half-life peptides (e.g., Semaglutide) can be dosed once or twice weekly.
Peak-to-Trough Variability
Peptides with short half-lives produce higher peak concentrations shortly after dosing, followed by lower trough levels before the next dose. This variability can affect the consistency of research outcomes.
Stack Compatibility
When stacking multiple peptides, understanding their individual half-lives helps you time administrations for synergistic effects or to avoid overlapping peak concentrations.
Reconstitution Planning
Peptides with shorter shelf-lives after reconstitution (typically 7–14 days when stored properly) need to be used quickly. See our Research-only notice: This article is for informational and research purposes only. It is not medical guidance, dosing instruction, or a recommendation to use any peptide compound. Consult a qualified healthcare professional before making any health-related decision.