Side-by-side · Research reference
HGH Fragment 176-191vsP21
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AAnimal-StrongHUMAN-REVIEWED28/59 cited
BAnimal-MechanisticHUMAN-REVIEWED8/36 cited
HGH Fragment 176-191
GH Fragment · Pre-Clinical
SQ · IP (animal) · Oral (tested)
P21
CNTF-Derived Neuropeptide · Animal Model Evidence
Animal onlyEvidence level
SQ · Site unspecified · Frequency unknown
01Mechanism of Action
Parameter
HGH Fragment 176-191
P21
Primary target
Beta-3 adrenergic receptors on adipocytesHeffernan 2001
CNTF receptor alpha (CNTFRα) / LIF receptor (LIFR) / gp130 complex on neural stem cells
Pathway
Fragment → β3-AR upregulation → Enhanced lipolytic sensitivityHeffernan 2001
CNTF mimetic → CNTFRα/LIFR/gp130 heterotrimer → JAK/STAT3 signaling → neurogenesis, stem cell proliferation, neuroprotection
Downstream effect
Increased lipolysis and beta-3 AR mRNA expression without IGF-1 axis activation
Increased neural stem cell self-renewal, globose basal cell activation (Mash1+ cells), olfactory sensory neuron regeneration, hippocampal neurogenesis, neuroprotection in developmental disorders
Feedback intact?
N/A — does not interact with GH/IGF-1 axis
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Origin
Synthetic peptide derived from hGH residues 176-191; AOD9604 includes N-terminal tyrosine (177-191)Cox 2015
Small-molecule peptide mimetic derived from full-length ciliary neurotrophic factor (CNTF), designed to retain receptor activation with improved pharmacokineticsMottolese 2024
Antibody development
Not reported in available studies
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02Dosage Protocols
Parameter
HGH Fragment 176-191
P21
Animal dose (IP)
Not specified (14-day chronic administration)Heffernan 2001
Obese mice, daily IP injection.
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Human equivalent dose
Not established — no published human RCTs
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Frequency
Once daily (animal models)
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Evidence basis
Animal studies only
Animal models only
CDKL5 KO mice, methimazole-induced olfactory injury, CNTF-/- knockout models.Mottolese 2024Cox 2026Jia 2020
Detection window
50 pg/mL LOD in urine; stable metabolite extends detectionCox 2015
WADA-banned; anti-doping testing available.
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Oral bioavailability
Demonstrated efficacy in animal oral administrationNg 2000
Potential for oral therapeutic development.
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Human dosing
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No established protocol
No clinical trial data available.
Animal models (mice)
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Dose and route not specified in abstractsMottolese 2024Jia 2020
In vitro and in vivo studies demonstrate efficacy; precise dosing protocols not disclosed.
Duration
—
Not specified
Route
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Presumed subcutaneous or intraperitoneal (animal studies)
03Metabolic / Fat Loss Evidence
Parameter
HGH Fragment 176-191
P21
Weight gain reduction
50% reduction vs control (15.8 ± 0.6 g vs 35.6 ± 0.8 g)Ng 2000
Obese Zucker rats, 19 days oral administration.
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Body fat reduction
Significant decrease in body weight and body fat in obese mice (14 days)Heffernan 2001
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Lipolytic activity
Increased adipose tissue lipolytic activityNg 2000
Direct measurement in treated animals.
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Insulin sensitivity
No adverse effect — euglycemic clamp confirmedNg 2000
Contrasts with intact hGH diabetogenic effects.
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IGF-1 impact
No elevation — fragment does not activate GH/IGF-1 axis
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Beta-3 AR dependency
Effect abolished in β3-AR knockout miceHeffernan 2001
Confirms β3-AR as primary mechanism.
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Human evidence
None published — pre-clinical only
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04Side Effects & Safety
Parameter
HGH Fragment 176-191
P21
Human safety data
Not available — no published human trials
None available
No clinical trials in humans.
Metabolic profile
Six metabolites identified; CRSVEGSCG most stableCox 2015
Detection window implications for doping control.
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Animal tolerability
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Well-tolerated in mouse models; no toxicity reported in available abstracts
Theoretical risks
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Uncontrolled stem cell proliferation, immune response to peptide, unknown long-term CNS effects
Absolute Contraindications
HGH Fragment 176-191
- ·Competitive athletes (WADA-banned)Cox 2015
P21
- ·Use in humans not validated
Relative Contraindications
HGH Fragment 176-191
- ·Absence of human safety data — experimental use only
P21
- ·Active malignancy (theoretical — neurotrophic signaling may affect tumour growth)
- ·Pregnancy or lactation (no safety data)
05Administration Protocol
Parameter
HGH Fragment 176-191
P21
1. Route
Subcutaneous injection primary route in research context. Oral administration demonstrated efficacy in animal models at 500 mcg/kg.
Not established. No FDA approval, no clinical trial data.
2. Frequency
Once daily dosing used in animal studies. Timing not specified; GH-independent mechanism suggests flexibility.
In vivo studies used systemic administration (route not specified in abstracts) in mouse models of neurodegeneration, olfactory injury, and CDKL5 deficiency disorder. In vitro studies used primary cell cultures.
3. Duration
Animal protocols: 14–19 days. Human duration not established — no published trials.
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4. Storage
Lyophilized peptide storage per standard peptide protocols. Metabolite stability suggests refrigerated reconstituted solution viable.
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5. Detection
Detectable in urine via SPE-LC-MS at 50 pg/mL LOD. Extended detection window via stable metabolite CRSVEGSCG.Cox 2015
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