Side-by-side · Research reference
IpamorelinvsPEG-MGF
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
APhase 1HUMAN-REVIEWED21/57 cited
BAnimal-MechanisticHUMAN-REVIEWED2/69 cited
Ipamorelin
Selective GHRP · Ghrelin Mimetic
SQ · Multiple sites · 1–3×/day
PEG-MGF
IGF-1Ec Splice Variant · PEGylated
~2 hrHalf-life (PEG)
~7 minNative MGF t½
IGF-1EcSplice variant
SQ · Research Protocol
01Mechanism of Action
Parameter
Ipamorelin
PEG-MGF
Primary target
Ghrelin receptor (GHS-R1a) on anterior pituitaryRaun 1998
IGF-1 receptor on muscle satellite cells and myocytes
Pathway
GHS-R1a binding → Gαq/11 → ↑intracellular Ca²⁺ → GH vesicle exocytosisRaun 1998Bowers 1991
IGF-1R → PI3K/Akt → mTOR activation → Satellite cell proliferation & myoblast fusion
Downstream effect
GH pulse amplification, IGF-1 elevation, recovery and lipolytic effectsBowers 2002
Satellite cell activation, muscle fiber repair, localized hypertrophy signaling
Feedback intact?
Yes — pulsatile pattern preserved; somatostatin feedback activeBowers 2002
Partially bypassed — does not require hepatic IGF-1 synthesis
Origin
Pentapeptide H-Aib-His-D-2-Nal-D-Phe-Lys-NH₂; rationally designed for ghrelin-receptor selectivityRaun 1998
IGF-1Ec splice variant (exon 4–6) conjugated to polyethylene glycol for extended circulation
Antibody development
Not reported in short-term studies
Unknown — no long-term human immunogenicity data
02Dosage Protocols
Parameter
Ipamorelin
PEG-MGF
Standard dose
200–300 mcg per injectionRaun 1998
Anecdotal community range; clinical doses 1–3 mg IV in trials.
—
Frequency
1–3× per day
Once daily pre-sleep is most common; twice or thrice for advanced users.
Post-training or daily
Timing to match endogenous MGF pulse post-exercise.
Lower / starter dose
100 mcg per dose
—
Duration
8–12 weeks on / 4 weeks off (anecdotal)
GHS-R desensitisation reported with continuous dosing.
—
Reconstitution
Bacteriostatic water; typical 2 mL per 5 mg vial
Sterile bacteriostatic water
Lyophilized form; store reconstituted at 2–8 °C.
Timing
Pre-sleep + fasted preferred; 30 min away from food
Within 30–60 min post-training
Aligns with endogenous MGF window.
Half-life
~2 hoursRaun 1998
Longer than GHRP-6 (15 min); shorter than CJC-1295-DAC (~8 days).
~2 hours (PEGylated)
Native MGF: ~7 min; PEGylation extends circulation.
Research dose range
—
100–200 mcg
Extrapolated from animal models; no validated human protocols.
PEG molecular weight
—
Typically 5–30 kDa
Higher MW = longer t½, greater steric hindrance.
03Metabolic / Fat Loss Evidence
Parameter
Ipamorelin
PEG-MGF
Primary target
—
Muscle tissue (satellite cells, myocytes) — not adipose-specific
Indirect metabolic effect
—
IGF-1 signaling may modulate insulin sensitivity and lipid metabolismRen 2015
Mechanism distinct from direct lipolytic peptides.
Body composition
—
Lean mass preservation / hypertrophy focus
Fat loss evidence
—
No direct human or animal RCT data for PEG-MGF-driven fat reduction
04Side Effects & Safety
Parameter
Ipamorelin
PEG-MGF
Hunger
Mild appetite increase via ghrelin-receptor crosstalk
—
Injection site reaction
Mild irritation possible
Erythema, induration (common with SQ peptides)
GH excess (overdose)
Joint pain, edema, insulin resistance
—
IGF-1 elevation
Dose-dependent; monitor with chronic high-dose use
—
Cancer risk
Theoretical via GH/IGF-1 axis; contraindicated in active malignancy
IGF-1 axis stimulation contraindicated in active malignancy
Pregnancy / OB
Avoid
—
Hypoglycemia risk
—
IGF-1 axis activation can lower blood glucose
IGF-1R overstimulation
—
Theoretical risk of aberrant cell proliferation with chronic supraphysiological exposure
Fluid retention
—
Possible with IGF-1 pathway activation (dose-dependent)
PEG accumulation
—
Chronic high-dose PEGylated proteins may accumulate in tissues; clearance slower in renal impairment
Antibody formation
—
PEGylated proteins can elicit anti-PEG antibodies (neutralizing potential unknown)
Human safety data
—
Absent — no published human trials for PEG-MGF
Absolute Contraindications
Ipamorelin
- ·Active malignancy or cancer history
- ·Pregnancy / breastfeeding
- ·Disrupted hypothalamic-pituitary axis
PEG-MGF
- ·Active malignancy or history of cancer (IGF-1R proliferative signaling)
- ·Known hypersensitivity to PEGylated compounds
- ·Pregnancy / lactation (no reproductive toxicity data)
Relative Contraindications
Ipamorelin
- ·Untreated diabetes
- ·Severe insulin resistance
- ·Concurrent corticosteroid use (theoretical desensitisation)
PEG-MGF
- ·Diabetes (monitor glucose closely)
- ·Renal impairment (PEG clearance reduced)
- ·Retinopathy (IGF-1 axis effects on vascular proliferation)
05Administration Protocol
Parameter
Ipamorelin
PEG-MGF
1. Reconstitution
Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL. Roll gently. Solution should be clear.
Add 1–2 mL bacteriostatic water to lyophilized vial. Swirl gently — do not shake. Solution should be clear to slightly opalescent.
2. Injection site
Subcutaneous, abdomen or thigh. Rotate sites. Pinch fat for shallow SQ delivery.
Subcutaneous — abdomen or thigh. Rotate sites to avoid lipodystrophy. Avoid areas with scar tissue or active inflammation.
3. Timing
Pre-sleep optimal — aligns with natural GH pulse. Some protocols add a morning fasted dose.
Post-training preferred (within 30–60 min) to align with endogenous MGF expression window. Alternatively, daily morning dose on non-training days.
4. Storage
Lyophilised: room temp, protected from light. Reconstituted: refrigerate 2–8 °C, use within 30 days.
Lyophilized: room temperature, light-protected, desiccated. Reconstituted: refrigerate 2–8 °C, use within 14–21 days.
5. Needle
29–31G, 4–8 mm insulin syringe.
29–31G insulin syringe, 8–12 mm length. Pinch skin fold, insert at 45° angle for subcutaneous delivery.
06Stack Synergy
Ipamorelin
+ Tesamorelin
StrongIpamorelin (GHRP) + tesamorelin (GHRH analogue) is the textbook dual-axis GH stack. They activate two distinct pituitary receptors — the ghrelin receptor and the GHRH receptor — producing a synergistic GH pulse larger than either alone. Ipamorelin's selectivity (no cortisol/prolactin spike) makes it the ideal GHRP partner for long-term protocols.
- Ipamorelin
- 200–300 mcg SQ · pre-sleep
- Tesamorelin
- 2 mg SQ · same injection · pre-sleep
- Primary benefit
- Maximal GH pulsatility, fat loss, recovery, sleep depth
+ CJC-1295 (no DAC)
StrongCJC-1295 (no DAC) is a short-acting GHRH analogue. Combined with ipamorelin (GHRP), the pulse is amplified across both receptor systems with timing similar to native physiology. Without the DAC modification, the stack maintains sharp peaks rather than the sustained elevation seen with CJC-1295-DAC + ipamorelin.
- Ipamorelin
- 200–300 mcg SQ · pre-sleep
- CJC-1295 (no DAC)
- 100 mcg SQ · same injection
- Primary benefit
- Pulsatile GH stimulation matching physiological pattern
PEG-MGF
+ BPC-157
ModerateBPC-157 promotes angiogenesis and tendon/ligament repair via VEGF and growth factor modulation, while PEG-MGF targets satellite cell activation and myocyte proliferation. Complementary pathways for comprehensive tissue repair post-injury or intensive training. BPC-157's systemic stability and oral bioavailability contrast with PEG-MGF's localized IGF-1R signaling.
- PEG-MGF
- 100–200 mcg SQ post-training
- BPC-157
- 250–500 mcg SQ or oral, twice daily
- Duration
- 4–6 weeks (injury-dependent)
- Primary benefit
- Accelerated muscle and connective tissue repair, enhanced recovery
+ TB-500
StrongTB-500 (Thymosin Beta-4 fragment) upregulates actin polymerization, cell migration, and anti-inflammatory pathways, while PEG-MGF drives satellite cell proliferation via IGF-1R/mTOR. Synergistic for muscle regeneration: TB-500 mobilizes progenitor cells, PEG-MGF stimulates their differentiation into myocytes. Both have overlapping but distinct repair cascades.
- PEG-MGF
- 100–200 mcg SQ post-training
- TB-500
- 2–5 mg SQ, 2× per week (loading), then weekly
- Timing
- Stagger injections by 6–12 hours
- Primary benefit
- Maximal satellite cell recruitment and myogenic differentiation, injury repair