No. MK-677 (Ibutamoren) is a non-peptide small molecule — a spiroindane-based ghrelin receptor agonist — that is orally bioavailable and acts on the same receptor as GHRP peptides.

Pillar 3 · Longevity, GH Axis & Anti-Aging

Longevity peptides: two families, very different evidence bases, and a lot of marketing filling the gap between them.

Q: What are longevity peptides, and do they actually work?

'Longevity peptide' is a marketing category. GH-axis peptides have Phase II–III human trial data for body composition; they do not have evidence for extended human lifespan. Russian bioregulators lack independent Western Phase II–III replication. 'Work' depends on the outcome asked about and the evidence quality required.

Q: What is the difference between CJC-1295 with DAC and without DAC?

CJC-1295 without DAC (Modified GRF 1-29) has a 15–30 minute half-life producing pulsatile GH. CJC-1295 with DAC binds albumin, extending half-life to ~7 days for sustained GH/IGF-1 elevation. The Teichman 2006 Phase II used the DAC version.

Q: What evidence exists for Epitalon?

Epitalon evidence comes primarily from the Khavinson group in St. Petersburg: in vitro telomerase activation, rodent lifespan data, and Soviet-era clinical trials. No independent Western Phase II/III replication exists as of April 2026.

Q: Is the CJC-1295 + Ipamorelin stack evidence-based?

The pharmacokinetic rationale (synergistic GH pulse via two receptor pathways) is mechanistically sound. Whether the larger GH pulse produces body-composition or anti-aging outcomes in humans has not been answered in an adequately powered RCT. Long-term safety in healthy adults has not been studied.

By PeptideRadar Research Desk · April 18, 2026

Spokes30 articles Pillar keywordlongevity peptides Est. US vol2,900/mo Evidence rangeSoviet gerontology to Phase III Updated2026-04-18

The longevity peptide space divides into two families that rarely get honestly compared. The GH-axis family — CJC-1295, Ipamorelin, MK-677, Tesamorelin, Sermorelin, GHRP-2, GHRP-6 — has Phase II and Phase III human trial data, a clear receptor pharmacology, and a defined regulatory history. The Russian bioregulator family — Epitalon, Thymalin, Pinealon, Thymulin — has Soviet-era gerontology literature, some translated publications in Neuroendocrinology Letters, and a compelling theoretical framework about peptide regulation of gene expression. Neither family is what its marketing says it is.

Key points

Two mechanistically distinct families: GH-axis peptides (GHRH analogs and GHRP/ghrelin-receptor agonists) and Russian bioregulators (short peptide chains believed to regulate tissue-specific gene expression).
GH-axis peptides have the stronger evidence base: multiple Phase II–III RCTs, including Teichman et al. 2006 (CJC-1295), Nass et al. 2008 (MK-677), and Falutz et al. 2007 (Tesamorelin). None are proven "anti-aging drugs" — they optimize GH-axis parameters.
Epitalon (tetrapeptide Ala-Glu-Asp-Gly) is the most researched bioregulator; the primary human data comes from the Khavinson group in St. Petersburg and has not been independently replicated in Western Phase II/III trials.
No compound in this cluster is FDA-approved as an anti-aging or longevity therapy. Tesamorelin (Egrifta SV) is FDA-approved for HIV-associated lipodystrophy — a specific metabolic indication.
The "anti-aging" narrative is a marketing extrapolation from endpoints (GH elevation, IGF-1 rise, telomerase activation in vitro) that have not been linked to longevity outcomes in adequately powered human trials.
Stack combinations (most commonly CJC-1295 + Ipamorelin) are widely used in compounding-pharmacy practice but lack long-term safety data in healthy adults.

How this cluster is organised

The thirty spokes in this pillar map onto four sub-clusters: the GHRH-analog sub-cluster, the GHRP/ghrelin-agonist sub-cluster, the Russian-bioregulator sub-cluster, and a set of newer mitochondria-targeting peptides (SS-31, MOTS-c, Humanin) that arrived from geroscience research in the 2010s. Understanding which sub-cluster a compound belongs to is the first step in evaluating any claim made about it.

Sub-cluster 1: GHRH analogs

Growth-hormone-releasing hormone (GHRH) is the hypothalamic peptide that drives GH synthesis in pituitary somatotrophs. Its native sequence is a 44-amino-acid peptide; the first 29 residues carry full biological activity. Research peptides in this family are synthetic analogs engineered for extended half-life.

CJC-1295 is the most widely discussed GHRH analog in research-peptide contexts. The name has been used loosely to describe two chemically distinct compounds: CJC-1295 with DAC (drug-affinity complex) and CJC-1295 without DAC (also called Modified GRF 1-29 or Mod GRF 1-29). Only the DAC version has the extended half-life (~7 days) that drives its "bleed" pharmacokinetics; without DAC, half-life is measured in minutes, similar to native GHRH. Teichman et al. (J Clin Endocrinol Metab, 2006; PMID 16352683) is the landmark Phase II that measured CJC-1295-DAC's prolonged GH and IGF-1 stimulation in healthy adults. Our CJC-1295 research page works through this distinction in full.

Tesamorelin is the only FDA-approved GHRH analog. It received approval in 2010 for HIV-associated lipodystrophy under the brand name Egrifta and Egrifta SV. Falutz et al. (N Engl J Med, 2007; PMID 18057338) established its Phase III efficacy for visceral fat reduction in HIV patients. The existence of an approved drug in this class validates the receptor pharmacology; it does not validate the off-label uses marketed in the research-peptide space. Our Tesamorelin research page is the authoritative entry in this cluster.

Sermorelin is the 29-residue N-terminal fragment of GHRH, once FDA-approved for pediatric GH deficiency (withdrawn from US market in 2008 for commercial reasons, not safety). Sermorelin's short half-life (~10 minutes in plasma) means it works through physiological pulsatile GH release rather than sustained elevation. Spoke 3.15 (Sermorelin research page) covers its clinical history and comparison with CJC-1295.

Sub-cluster 2: GHRPs and ghrelin-receptor agonists

Growth-hormone-releasing peptides (GHRPs) and non-peptide ghrelin mimetics stimulate GH release through the ghrelin receptor (GHS-R1a) — a different pathway than GHRH analogs. Combining a GHRH analog with a GHRP produces a larger, synergistic GH pulse than either class alone, which is the pharmacokinetic rationale for the CJC-1295 + Ipamorelin stack.

Ipamorelin is the most selectivity-refined GHRP in the class. It stimulates GHS-R1a without the parallel cortisol and prolactin spikes associated with GHRP-6 and hexarelin. Raun et al. (Eur J Endocrinol, 1998; PMID 9849822) is the founding pharmacological characterisation. Novo Nordisk advanced it to Phase II for postoperative ileus; it failed on that endpoint and the program was discontinued. Our Ipamorelin research page is the primary spoke entry.

MK-677 (Ibutamoren) is not a peptide — it is a non-peptide oral ghrelin mimetic (small molecule GHSR1a agonist) developed by Merck. It is placed in this pillar because its mechanism, pharmacological effects, and research-market positioning overlap completely with the peptide GHRPs. Nass et al. (Ann Intern Med, 2008; PMID 18981485) is the landmark: a 2-year double-blind RCT in 65 healthy elderly adults showing increased lean mass and IGF-1, but also side effects including edema, hyperglycemia signals, and increased fasting glucose. Merck discontinued development. Full coverage in our MK-677 research page.

The comparison between MK-677 and Ipamorelin — oral vs injectable, sustained vs pulsed GH elevation, side-effect profiles — is covered in spoke 3.6 (MK-677 vs Ipamorelin). GHRP-6 and GHRP-2 are covered in spokes 3.13 and 3.14; they are less selective than Ipamorelin and produce stronger appetite and cortisol signals.

Sub-cluster 3: Russian bioregulators

The bioregulator family originates from the Institute of Bioregulation and Gerontology in St. Petersburg, led for decades by Vladimir Khavinson. The theoretical framework holds that short peptides (2–4 amino acids) derived from specific tissues can penetrate cells, interact with chromatin, and regulate the expression of genes relevant to that tissue's aging. The concept is called "cytomedicines" or "peptide bioregulation."

Epitalon (tetrapeptide Ala-Glu-Asp-Gly; also spelled Epithalon or Epithalamin) is derived from the bovine pineal gland extract Epithalamin. Khavinson's group published data on telomerase activation in human fibroblasts and somatic cells (Khavinson et al., Bulletin of Experimental Biology and Medicine, 2003), circadian rhythm normalization, and lifespan extension in rodent models. Some human studies were conducted in Soviet-era clinical settings. The key honest caveat: most primary data is Russian-language; translated summaries appear in Neuroendocrinology Letters but have not been independently replicated in Western Phase II/III-equivalent trials. Our Epitalon research page documents this evidence limitation explicitly.

Thymalin (spoke 3.3, Thymalin page) is derived from bovine thymus and is theorised to support immune regulation and cellular regeneration. Like Epitalon, the primary literature is from the Khavinson group, published predominantly in Russian with some English translations. Pinealon (spoke covered in Cognitive pillar, 2.12) is a tripeptide with claimed neuroprotective and circadian effects.

Evidence gap — bioregulators The bioregulator family presents a genuine evidence interpretation challenge. The Khavinson group has published prolifically and the mechanistic hypotheses (peptide-DNA interaction, telomerase modulation) are biologically plausible. But "biologically plausible" and "proven in adequately powered human trials" are very different standards. Researchers approaching this family should read primary Khavinson citations rather than vendor summaries, and hold conclusions proportionally to the trial quality.

Sub-cluster 4: Mitochondria-targeting and newer geroscience peptides

A newer generation of longevity-relevant peptides emerged from basic geroscience research: SS-31 (Elamipretide), MOTS-c, and Humanin. These are mechanistically distinct from both GH-axis and bioregulator families — they target mitochondrial function, AMPK signalling, and cellular stress responses. Evidence stage is mostly preclinical or early-Phase I. Spokes 3.10 (Humanin), 3.20 (SS-31/Elamipretide), and 3.21 (MOTS-c) cover each; spoke 3.22 (peptides and NAD+ pathways) connects this group to the sirtuins/NAD story that has dominated popular longevity discourse.

Evidence hierarchy across the cluster

Compound / class	Best evidence stage	Human RCT?	Key caveat
Tesamorelin	Stage 7 — FDA approved (lipodystrophy)	Yes (Phase III)	Approved only for HIV-associated lipodystrophy; off-label use lacks comparable data
MK-677 (Ibutamoren)	Stage 6 — Phase III equivalent (Nass 2008)	Yes	Merck discontinued; side-effect signals (edema, hyperglycemia) at 2 years
Sermorelin	Stage 7 — FDA-approved (pediatric GHD, withdrawn 2008)	Yes	US market withdrawal was commercial, not safety-driven; adult longevity use is off-label
CJC-1295	Stage 5 — Phase II (Teichman 2006)	Yes (healthy adults)	GH/IGF-1 surrogate endpoints only; no longevity outcomes measured
Ipamorelin	Stage 5 — Phase II (Beck 2014)	Yes (GI motility indication)	Discontinued; no longevity/body-composition RCT published
GHRP-2 / GHRP-6	Stage 4–5 — Phase I/II PK work	Limited	Older peptides with less-selective receptor profiles; cortisol/prolactin signal
Epitalon	Stage 4 (Russian clinical studies)	Limited (Khavinson group only)	No independent Western Phase II replication; evidence gap must be disclosed
Thymalin	Stage 3–4	Limited (Khavinson group only)	Same evidence-quality caveat as Epitalon
SS-31 / MOTS-c / Humanin	Stage 1–3 — primarily preclinical	No (for longevity endpoints)	Promising mechanistic work; no adequately powered human longevity RCTs

The spoke articles, by sub-topic

GH-axis deep-dive spokes

The Ipamorelin spoke (3.1) is the highest-volume entry in this cluster and covers the ghrelin-receptor mechanism in depth. Our CJC-1295 spoke (3.11) is the essential companion — it distinguishes the DAC vs no-DAC chemistry and covers the Teichman 2006 Phase II data. The CJC-1295 + Ipamorelin stack spoke (3.12) addresses the most commonly compounded peptide combination in clinical anti-aging and optimization practice, including the pharmacokinetic rationale and the complete absence of long-term safety data. Our Tesamorelin spoke (3.7) is the FDA-approved anchor that demonstrates what rigorous GHRH-analog evidence looks like.

For comparison content: spoke 3.6 (MK-677 vs Ipamorelin) compares the oral vs injectable ghrelin-mimetic options. Spoke 3.16 (Sermorelin vs Ipamorelin) compares the two historically dominant injectable GH-optimization options. Spoke 3.15 (Sermorelin) covers Sermorelin's full clinical history.

MK-677 and ghrelin-mimetic spokes

Our MK-677 research page (3.5) is the highest-volume spoke in the cluster (estimated 49,500/mo search volume) and the most important for reaching the mainstream GH-optimization audience. It covers Ibutamoren's chemistry (not a peptide; a spiroindane-based small molecule), Merck's development history, the Nass 2008 Ann Intern Med RCT, and why the compound was discontinued. Spoke 3.25 (MK-677 side effects) covers the edema, hyperglycemia, and cortisol signals from that trial in depth.

Bioregulator spokes

Our Epitalon spoke (3.2) is the entry point for the Russian-bioregulator family. It covers the Khavinson group's tetrapeptide hypothesis, telomerase activation data, circadian-pineal connection, and the evidence-quality limitations that any honest treatment must acknowledge. Spoke 3.28 (Epitalon cycle and protocol) addresses what the limited human observational data suggests about use patterns. Spoke 3.3 (Thymalin) covers the immune-supporting thymus-derived bioregulator. GHK-Cu anti-aging (spoke 3.4, GHK-Cu anti-aging page) bridges to the Skin pillar with the copper-tripeptide's skin and connective-tissue evidence.

Geroscience peptides and NAD+ pathway spokes

Spoke 3.20 (SS-31/Elamipretide) covers the mitochondria-targeting tetrapeptide with clinical trial data for heart failure (Szeto-Schiller peptide). Spoke 3.21 (MOTS-c) covers the mitochondria-derived peptide with AMPK-activation and metabolic data. Spoke 3.10 (Humanin) covers the small 21-residue mitochondria-encoded peptide with neuroprotective signals in rodent models. Spoke 3.29 (peptides and cellular senescence) and spoke 3.30 (peptides and telomere biology) connect this group to the wider hallmarks-of-aging literature.

Population and protocol spokes

Spoke 3.18 (anti-aging peptides for women) and spoke 3.19 (peptides for men over 40) apply the evidence base to the primary demographic audiences. Spoke 3.23 (best longevity peptide stack) synthesises the stacking rationale across the cluster for researchers evaluating multi-compound protocols.

Cross-cluster bridges

This pillar shares mechanistic territory with three adjacent clusters. The Muscle & Recovery pillar touches the GH axis from an anabolic angle — researchers following muscle-growth rationale into GH peptides should read both clusters. The Weight & Metabolic pillar is where Tesamorelin's visceral-fat evidence fully resides alongside GLP-1 data; the GH+GLP-1 combination stacking discussion bridges both clusters. The Skin & Dermatological pillar covers GHK-Cu's topical formulation story, a distinct context from this cluster's systemic anti-aging framing.

Regulatory caution — this entire cluster None of the compounds covered in this pillar (except Tesamorelin for its approved indication) are approved as anti-aging, longevity, or health-optimization therapies by the FDA, EMA, or any major regulatory body. The category is research-use-only. Claims that any of these peptides extend human lifespan, reverse aging, or produce specific health outcomes are not supported by the published evidence to the standard required for drug approval.

Frequently asked

What are longevity peptides, and do they actually work?

"Longevity peptide" is a marketing category, not a regulatory or scientific classification. The compounds grouped here share a common marketing narrative (anti-aging, GH optimization, cellular rejuvenation) but divide into mechanistically distinct families with very different evidence qualities. GH-axis peptides have Phase II–III human trial data for body composition and GH-axis parameters; they do not have evidence for extended human lifespan. Russian bioregulators have a theoretical framework and Soviet-era clinical data; they lack independent Western Phase II–III replication. "Work" depends entirely on what outcome you're asking about and what evidence quality you require.

Is MK-677 a peptide?

No. MK-677 (Ibutamoren) is a non-peptide small molecule — specifically a spiroindane-based ghrelin receptor agonist. It is classified and marketed alongside GHRPs because it acts on the same receptor (GHS-R1a) and produces similar GH-secretion effects. Chemically, it is not a peptide, and it is orally bioavailable where peptide GHRPs require injection. This matters because its pharmacokinetics, metabolism, and regulatory classification differ from peptide secretagogues.

What is the difference between CJC-1295 with DAC and without DAC?

CJC-1295 without DAC (also called Modified GRF 1-29 or Mod GRF 1-29) is a stabilized 29-residue GHRH analog with a plasma half-life of 15–30 minutes. CJC-1295 with DAC has a drug-affinity complex (DAC) that enables covalent binding to albumin, extending half-life to approximately 7 days. This distinction fundamentally changes pharmacokinetics: no-DAC produces a clean pulsatile GH signal; DAC produces sustained (bleed) GH/IGF-1 elevation. The Teichman 2006 Phase II was conducted with the DAC version. Most research-chemical vendors sell the DAC version when labeling says "CJC-1295" without qualification.

What evidence exists for Epitalon?

The primary Epitalon evidence base comes from the Khavinson group at the Institute of Bioregulation and Gerontology in St. Petersburg. Published work includes in vitro telomerase activation in human somatic cells, rodent lifespan studies, and Soviet/Russian clinical trials of Epitalamin (the pineal extract precursor to synthetic Epitalon). Translated summaries appear in Neuroendocrinology Letters and Bulletin of Experimental Biology and Medicine. No independent Western Phase II or Phase III replication exists. This is an honest statement of the literature, not a dismissal — but researchers should weight it accordingly.

Is the CJC-1295 + Ipamorelin stack evidence-based?

The pharmacokinetic rationale is mechanistically sound: GHRH-receptor stimulation (CJC-1295) and GHS-R1a stimulation (Ipamorelin) produce synergistically larger GH pulses than either alone, as established in basic pharmacology work. Whether that larger GH pulse produces the body-composition or anti-aging outcomes attributed to the stack in research-market materials is a different question — and that question has not been answered in an adequately powered human RCT conducted specifically on this combination. The stack's long-term safety in healthy adults has not been studied.

Are any of these compounds available through legitimate medical channels?

Tesamorelin (Egrifta SV) is FDA-approved and available by prescription for its approved indication. Sermorelin was FDA-approved and is available through 503A compounding pharmacies in some states for adult GH deficiency; its availability has varied with FDA guidance changes. Other compounds in this cluster — CJC-1295, Ipamorelin, MK-677, Epitalon — are not FDA-approved and are not available through mainstream pharmaceutical channels. They are sold under research-use-only framing by peptide research vendors.

Reviewer sign-off Reviewed 2026-04-18 by the PeptideRadar Research Desk. This pillar page is a navigational overview; each linked spoke article contains the primary citations for its compound. Evidence tiers assigned per published human-trial data as of April 2026. Corrections policy: errors are flagged in a dated note appended to this article. Contact: corrections@peptideradar.net.