Peptide Comparison

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AI comparison summary

Biggest differences across Ipamorelin · CJC-1295 · Retatrutide

Focused on evidence grade, pharmacokinetics, and risks/interactions — with inline citations to the primary references on each peptide page.

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Ipamorelin

Grade BGrowth Hormone

Overview

Evidence grade: Grade B
Category: Growth Hormone
Primary focus: Selective GH secretagogue
Summary: Frequently combined with CJC-1295 to mimic physiological GH pulsatility. Cleaner side-effect profile than GHRP-2/6.

Mechanism

Mechanism of action: Pentapeptide ghrelin receptor (GHS-R1a) agonist that selectively stimulates pituitary GH release without significant effects on cortisol, prolactin, or appetite — unlike earlier secretagogues.
Evidence explainer: Grade B — supported by preclinical evidence plus at least one small human trial, pharmacokinetic study, or strong translational rationale. Human long-term safety is incomplete.

Pharmacokinetics

Route: Subcutaneous injection
Half-life: ~2 hours
PK notes: Ipamorelin is administered subcutaneous injection with an approximate systemic half-life of ~2 hours. Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (1–3× daily) is designed to match receptor kinetics rather than plasma exposure. Pentapeptide ghrelin receptor (GHS-R1a) agonist that selectively stimulates pituitary GH release without significant effects on cortisol, prolactin, or appetite — unlike earlier secretagogues.

Administration

Typical dose: 200–300 mcg
Frequency: 1–3× daily
Cycle length: 8–12 week cycles
Timing: Pre-bed and/or pre-training, fasted
Protocol steps: Route: Subcutaneous injection. Typical starting dose 200–300 mcg, 1–3× daily.
Timing: Pre-bed and/or pre-training, fasted — keep it the same each dosing day to make effects legible.
Cycle length: 8–12 week cycles. Reassess with bloods and symptom logs before repeating.
Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.

Benefits

Reported benefits: Selective GH pulse without cortisol elevation
Improved recovery and sleep quality
Minimal appetite stimulation
Common stacks: CJC-1295, Resistance training, Casein pre-bed

Risks

Side effects: Mild head rush
Transient flushing
Injection site reaction
Contraindications: Active malignancy
Pregnancy
Uncontrolled diabetes
Interactions: GHRH analogues (CJC-1295) — Synergistic GH release.
Somatostatin analogues — Antagonistic — avoid combination.
Legal status: Research chemical. Not approved for human therapeutic use.

CJC-1295

Grade BGrowth Hormone

Overview

Evidence grade: Grade B
Category: Growth Hormone
Primary focus: Long-acting GHRH analogue
Summary: Used in research and off-label protocols to amplify endogenous growth hormone pulses. Often paired with a ghrelin mimetic like Ipamorelin for synergistic GH release.

Mechanism

Mechanism of action: Modified growth hormone-releasing hormone (GHRH) analogue. With DAC (drug affinity complex), binds albumin to extend half-life, producing sustained pulsatile GH and IGF-1 elevation.
Evidence explainer: Grade B — supported by preclinical evidence plus at least one small human trial, pharmacokinetic study, or strong translational rationale. Human long-term safety is incomplete.

Pharmacokinetics

Route: Subcutaneous injection
Half-life: ~8 days (with DAC); ~30 min (without DAC)
PK notes: CJC-1295 is administered subcutaneous injection with an approximate systemic half-life of ~8 days (with DAC); ~30 min (without DAC). Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (Weekly) is designed to match receptor kinetics rather than plasma exposure. Modified growth hormone-releasing hormone (GHRH) analogue. With DAC (drug affinity complex), binds albumin to extend half-life, producing sustained pulsatile GH and IGF-1 elevation.

Administration

Typical dose: 1–2 mg (with DAC)
Frequency: Weekly
Cycle length: 8–12 week cycles
Timing: Evening, fasted
Protocol steps: Route: Subcutaneous injection. Typical starting dose 1–2 mg (with DAC), Weekly.
Timing: Evening, fasted — keep it the same each dosing day to make effects legible.
Cycle length: 8–12 week cycles. Reassess with bloods and symptom logs before repeating.
Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.

Benefits

Reported benefits: Sustained elevation of GH and IGF-1
Improved sleep depth (slow-wave sleep)
Reported body composition improvements
Common stacks: Ipamorelin, Resistance training, Adequate protein

Risks

Side effects: Water retention
Numbness/tingling
Elevated fasting glucose
Injection site reactions
Contraindications: Active malignancy
Diabetic retinopathy
Pregnancy
Interactions: Insulin — GH antagonizes insulin; monitor glucose.
Corticosteroids — Blunt GH response.
Legal status: Research chemical. Not approved for human therapeutic use.

Retatrutide

Grade AMetabolic

Overview

Evidence grade: Grade A
Category: Metabolic
Primary focus: Triple GIP/GLP-1/glucagon agonist
Summary: Phase II trial results showed ~24% mean weight loss at 48 weeks at the 12 mg dose — markedly exceeding tirzepatide and prior GLP-1 monotherapies. Currently in Phase III; not yet FDA-approved but expected to be a landmark obesity and metabolic therapy.

Mechanism

Mechanism of action: First-in-class triple agonist of GIP, GLP-1, and glucagon receptors. The GLP-1 and GIP arms drive glucose-dependent insulin secretion and satiety; the glucagon arm increases energy expenditure — producing the largest weight-loss effect of any incretin to date.
Evidence explainer: Grade A — supported by multiple randomised human trials or an approved regulatory indication. Mechanism, dosing and safety are well characterised in humans.

Pharmacokinetics

Route: Subcutaneous injection
Half-life: ~6 days (supports once-weekly dosing)
PK notes: Retatrutide is administered subcutaneous injection with an approximate systemic half-life of ~6 days (supports once-weekly dosing). Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (Once weekly) is designed to match receptor kinetics rather than plasma exposure. First-in-class triple agonist of GIP, GLP-1, and glucagon receptors. The GLP-1 and GIP arms drive glucose-dependent insulin secretion and satiety; the glucagon arm increases energy expenditure — producing the largest weight-loss effect of any incretin to date.

Administration

Typical dose: Titrated 2 mg → 4 mg → 8 mg → 12 mg
Frequency: Once weekly
Cycle length: Ongoing; weight regain occurs on cessation
Timing: Same day each week; any time of day
Protocol steps: Route: Subcutaneous injection. Typical starting dose Titrated 2 mg → 4 mg → 8 mg → 12 mg, Once weekly.
Timing: Same day each week; any time of day — keep it the same each dosing day to make effects legible.
Cycle length: Ongoing; weight regain occurs on cessation. Reassess with bloods and symptom logs before repeating.
Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.

Benefits

Reported benefits: ~24% mean weight loss at 48 weeks (Phase II)
Marked improvements in HbA1c, blood pressure, ApoB and liver fat
Convenient once-weekly dosing
Likely best-in-class cardiometabolic profile
Common stacks: Creatine monohydrate, Whey protein, Vitamin D3 + K2

Risks

Side effects: Nausea, vomiting, diarrhea (especially during titration)
Injection site reactions
Reduced appetite to the point of inadequate protein intake — pair with resistance training and protein targeting
Theoretical pancreatitis and gallbladder risk (class effect)
Contraindications: Personal or family history of medullary thyroid carcinoma
Multiple Endocrine Neoplasia type 2
Pregnancy and lactation
Prior severe reaction to GLP-1 agonists
Interactions: Insulin and sulfonylureas — Risk of hypoglycemia — dose reduction usually required.
Oral medications — Delayed gastric emptying may alter absorption; separate timing for narrow-therapeutic-index drugs.
Legal status: Investigational; not yet FDA-approved. Currently available only via clinical trials.

Attribute	Ipamorelin Grade BGrowth Hormone	CJC-1295 Grade BGrowth Hormone	Retatrutide Grade AMetabolic
Overview
Evidence grade	Grade B	Grade B	Grade A
Category	Growth Hormone	Growth Hormone	Metabolic
Primary focus	Selective GH secretagogue	Long-acting GHRH analogue	Triple GIP/GLP-1/glucagon agonist
Summary	Frequently combined with CJC-1295 to mimic physiological GH pulsatility. Cleaner side-effect profile than GHRP-2/6.	Used in research and off-label protocols to amplify endogenous growth hormone pulses. Often paired with a ghrelin mimetic like Ipamorelin for synergistic GH release.	Phase II trial results showed ~24% mean weight loss at 48 weeks at the 12 mg dose — markedly exceeding tirzepatide and prior GLP-1 monotherapies. Currently in Phase III; not yet FDA-approved but expected to be a landmark obesity and metabolic therapy.
Mechanism
Mechanism of action	Pentapeptide ghrelin receptor (GHS-R1a) agonist that selectively stimulates pituitary GH release without significant effects on cortisol, prolactin, or appetite — unlike earlier secretagogues.	Modified growth hormone-releasing hormone (GHRH) analogue. With DAC (drug affinity complex), binds albumin to extend half-life, producing sustained pulsatile GH and IGF-1 elevation.	First-in-class triple agonist of GIP, GLP-1, and glucagon receptors. The GLP-1 and GIP arms drive glucose-dependent insulin secretion and satiety; the glucagon arm increases energy expenditure — producing the largest weight-loss effect of any incretin to date.
Evidence explainer	Grade B — supported by preclinical evidence plus at least one small human trial, pharmacokinetic study, or strong translational rationale. Human long-term safety is incomplete.	Grade B — supported by preclinical evidence plus at least one small human trial, pharmacokinetic study, or strong translational rationale. Human long-term safety is incomplete.	Grade A — supported by multiple randomised human trials or an approved regulatory indication. Mechanism, dosing and safety are well characterised in humans.
Pharmacokinetics
Route	Subcutaneous injection	Subcutaneous injection	Subcutaneous injection
Half-life	~2 hours	~8 days (with DAC); ~30 min (without DAC)	~6 days (supports once-weekly dosing)
PK notes	Ipamorelin is administered subcutaneous injection with an approximate systemic half-life of ~2 hours. Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (1–3× daily) is designed to match receptor kinetics rather than plasma exposure. Pentapeptide ghrelin receptor (GHS-R1a) agonist that selectively stimulates pituitary GH release without significant effects on cortisol, prolactin, or appetite — unlike earlier secretagogues.	CJC-1295 is administered subcutaneous injection with an approximate systemic half-life of ~8 days (with DAC); ~30 min (without DAC). Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (Weekly) is designed to match receptor kinetics rather than plasma exposure. Modified growth hormone-releasing hormone (GHRH) analogue. With DAC (drug affinity complex), binds albumin to extend half-life, producing sustained pulsatile GH and IGF-1 elevation.	Retatrutide is administered subcutaneous injection with an approximate systemic half-life of ~6 days (supports once-weekly dosing). Steady-state and tissue-level effects can outlast plasma concentration, which is why dosing frequency (Once weekly) is designed to match receptor kinetics rather than plasma exposure. First-in-class triple agonist of GIP, GLP-1, and glucagon receptors. The GLP-1 and GIP arms drive glucose-dependent insulin secretion and satiety; the glucagon arm increases energy expenditure — producing the largest weight-loss effect of any incretin to date.
Administration
Typical dose	200–300 mcg	1–2 mg (with DAC)	Titrated 2 mg → 4 mg → 8 mg → 12 mg
Frequency	1–3× daily	Weekly	Once weekly
Cycle length	8–12 week cycles	8–12 week cycles	Ongoing; weight regain occurs on cessation
Timing	Pre-bed and/or pre-training, fasted	Evening, fasted	Same day each week; any time of day
Protocol steps	Route: Subcutaneous injection. Typical starting dose 200–300 mcg, 1–3× daily. Timing: Pre-bed and/or pre-training, fasted — keep it the same each dosing day to make effects legible. Cycle length: 8–12 week cycles. Reassess with bloods and symptom logs before repeating. Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.	Route: Subcutaneous injection. Typical starting dose 1–2 mg (with DAC), Weekly. Timing: Evening, fasted — keep it the same each dosing day to make effects legible. Cycle length: 8–12 week cycles. Reassess with bloods and symptom logs before repeating. Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.	Route: Subcutaneous injection. Typical starting dose Titrated 2 mg → 4 mg → 8 mg → 12 mg, Once weekly. Timing: Same day each week; any time of day — keep it the same each dosing day to make effects legible. Cycle length: Ongoing; weight regain occurs on cessation. Reassess with bloods and symptom logs before repeating. Rotate sites across the abdomen (avoiding a 2 cm radius around the navel), outer thighs and flanks. Never inject through a bruise or mole.
Benefits
Reported benefits	Selective GH pulse without cortisol elevation Improved recovery and sleep quality Minimal appetite stimulation	Sustained elevation of GH and IGF-1 Improved sleep depth (slow-wave sleep) Reported body composition improvements	~24% mean weight loss at 48 weeks (Phase II) Marked improvements in HbA1c, blood pressure, ApoB and liver fat Convenient once-weekly dosing Likely best-in-class cardiometabolic profile
Common stacks	CJC-1295, Resistance training, Casein pre-bed	Ipamorelin, Resistance training, Adequate protein	Creatine monohydrate, Whey protein, Vitamin D3 + K2
Risks
Side effects	Mild head rush Transient flushing Injection site reaction	Water retention Numbness/tingling Elevated fasting glucose Injection site reactions	Nausea, vomiting, diarrhea (especially during titration) Injection site reactions Reduced appetite to the point of inadequate protein intake — pair with resistance training and protein targeting Theoretical pancreatitis and gallbladder risk (class effect)
Contraindications	Active malignancy Pregnancy Uncontrolled diabetes	Active malignancy Diabetic retinopathy Pregnancy	Personal or family history of medullary thyroid carcinoma Multiple Endocrine Neoplasia type 2 Pregnancy and lactation Prior severe reaction to GLP-1 agonists
Interactions	GHRH analogues (CJC-1295) — Synergistic GH release. Somatostatin analogues — Antagonistic — avoid combination.	Insulin — GH antagonizes insulin; monitor glucose. Corticosteroids — Blunt GH response.	Insulin and sulfonylureas — Risk of hypoglycemia — dose reduction usually required. Oral medications — Delayed gastric emptying may alter absorption; separate timing for narrow-therapeutic-index drugs.
Legal status	Research chemical. Not approved for human therapeutic use.	Research chemical. Not approved for human therapeutic use.	Investigational; not yet FDA-approved. Currently available only via clinical trials.

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