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Peptide Database

Goals
Fat LossMuscle BuildingInjury HealingAnti-AgingCognitive EnhancementSleep OptimizationImmune SupportGut HealingSkin RejuvenationSexual Health
Peptides
Adipotide
Weight Management
AOD-9604
Weight Management
BPC-157
Healing & Recovery
Cagrilintide
Weight Management
CJC-1295
Growth Hormone
DSIP
Sleep & Recovery
Epithalon
Anti-Aging
GHK-Cu
Anti-Aging
GHRP-2
Growth Hormone
HCG
Hormone Support
Hexarelin
Growth Hormone
HGH
Growth Hormone
IGF-1 LR3
Growth Hormone
Kisspeptin
Hormone Support
Melanotan-2
Cosmetic
MOTS-C
Metabolic
NAD+
Anti-Aging
Oxytocin Acetate
Hormone Support
PEG-MGF
Recovery
PNC-27
Cancer Research
PT-141
Sexual Health
Retatrutide
Weight Management
Selank
Cognitive
Semaglutide
Weight Management
Semax
Cognitive
Sermorelin
Growth Hormone
Snap-8
Cosmetic
SS-31
Mitochondrial
TB-500
Healing & Recovery
Tesamorelin
Growth Hormone
Thymosin Alpha-1
Immune
Tirzepatide
Weight Management
Total Peptides: 32
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Peptide Comparison

CapromorelinvsMK-677 (Ibutamoren)

An oral ghrelin agonist originally developed by Pfizer that stimulates growth hormone and appetite. FDA-approved for veterinary use (Entyce and Elura) and investigated in human trials for age-related muscle wasting and appetite support.

The oral growth hormone secretagogue that tricks your body into producing more GH — no needles required.

Growth HormoneGrowth Hormone

At a Glance

Quick
comparison

Dose Range

Capromorelin

3–30 mg

MK-677 (Ibutamoren)

10–25 mg

Frequency

Capromorelin

Once daily

MK-677 (Ibutamoren)

Once daily

Administration

Capromorelin

Oral (capsule or tablet)

MK-677 (Ibutamoren)

Oral (capsule or liquid)

Cycle Length

Capromorelin

4-6 weeks

MK-677 (Ibutamoren)

8-12 weeks

Onset Speed

Capromorelin

Moderate (1-2 weeks)

MK-677 (Ibutamoren)

Moderate (1-2 weeks)

Evidence Level

Capromorelin

Moderate human trials (Phase 1-2)

MK-677 (Ibutamoren)

Moderate human trials (Phase 1-2)

Efficacy

Benefit
ratings

Capromorelin
MK-677 (Ibutamoren)

GH & IGF-1 Stimulation

Capromorelin88%
MK-677 (Ibutamoren)0%

Physical Function

Capromorelin82%
MK-677 (Ibutamoren)0%

Oral Convenience

Capromorelin92%
MK-677 (Ibutamoren)0%

Muscle and body composition

Capromorelin0%
MK-677 (Ibutamoren)85%

Recovery and athletic performance

Capromorelin0%
MK-677 (Ibutamoren)80%

Sleep quality and metabolic health

Capromorelin0%
MK-677 (Ibutamoren)75%

Technical Data

Compound
specifications

Capromorelin

Molecular Formula

C28H35N5O4

Molecular Weight

505.6 g/mol

Half-Life

1-2.4 hours in humans

Bioavailability

Good oral bioavailability

CAS Number

193273-66-4

MK-677 (Ibutamoren)

Molecular Formula

C27H36N4O5S

Molecular Weight

528.7 g/mol

Half-Life

4-6 hours (IGF-1 elevation persists ~24 hours)

Bioavailability

High oral bioavailability

CAS Number

159634-47-6

Applications

Best
suited for

Capromorelin

Age-Related Muscle Wasting

Capromorelin showed significant improvements in physical function — including tandem walk and stair climb — in elderly adults, making it a strong candidate for combating sarcopenia.

Appetite Stimulation

As an FDA-approved veterinary appetite stimulant, capromorelin has extensive real-world evidence for boosting food intake and body weight in mammals.

Growth Hormone Research

One of the best-studied oral ghrelin agonists with human Phase 2 data, offering researchers a well-characterized tool for studying GH/IGF-1 pathways.

MK-677 (Ibutamoren)

Older Adults (60+) Seeking Body Composition Improvements

MK-677 was designed for aging populations. It restores GH and IGF-1 to youthful levels, increases lean mass, and improves physical function in people over 60. A 2-year clinical trial showed a 1.1 kg gain in fat-free mass with only modest fat gain—ideal for maintaining strength in older age.

Athletes and Fitness Enthusiasts Wanting Recovery Support

Oral dosing makes MK-677 convenient for athletes. It enhances muscle protein synthesis, speeds recovery after intense training, and supports lean mass building without the hassle of injections.

People with Chronic Wasting or Protein Deficiency

Clinical trials show MK-677 helps treat protein-energy wasting in kidney disease and other conditions. It stimulates appetite (a feature in these populations) and preserves muscle tissue—making it useful for those losing mass despite good nutrition.

Safety Profile

Side
effects

Capromorelin

Common

  • Appetite stimulation
  • Fluid retention and weight gain

Uncommon

  • Joint and muscle aches
  • Fatigue or lethargy
  • Peripheral edema (swelling)

Serious

  • Hyperglycemia

MK-677 (Ibutamoren)

Common

  • Increased appetite
  • Mild water retention or edema
  • Elevated fasting glucose

Uncommon

  • Joint or muscle pain
  • Carpal tunnel syndrome or nerve compression symptoms
  • Mild nausea or digestive upset

Serious

  • Glucose dysregulation and diabetes risk

Research Status

Safety
& evidence

Capromorelin

Evidence Level

Moderate human trials (Phase 1-2)

FDA Status

FDA approved for this use

Safety Overview

Capromorelin was generally well-tolerated in Phase 2 human trials involving nearly 400 elderly participants. Most side effects were mild to moderate. Its FDA-approved veterinary use provides additional long-term safety data in mammalian species.

Contraindications

  • xActive cancer or history of cancer (GH may stimulate growth)
  • xUncontrolled diabetes or severe metabolic disorders
  • xSevere liver or kidney disease
  • xPregnancy and lactation

MK-677 (Ibutamoren)

Evidence Level

Moderate human trials (Phase 1-2)

FDA Status

Research compound

Safety Overview

MK-677 has been studied in hundreds of humans over 2+ years and is generally well tolerated. Most side effects are mild and manageable, especially with lower starting doses. The lack of injection requirement makes it safer than injectable GH in terms of infection risk and sterility concerns. However, it is not FDA approved and should be viewed as a research compound.

Contraindications

  • xUncontrolled diabetes or severe glucose dysregulation
  • xActive cancer or high cancer risk requiring caution with IGF-1 elevation
  • xPregnancy or breastfeeding

Decision Guide

Which is
right for you?

Choose Capromorelin if...

  • Stimulating growth hormone production in elderly adults
  • Supporting appetite and weight gain in wasting conditions
  • Improving muscle mass and physical performance
  • Anti-aging and longevity optimization

Choose MK-677 (Ibutamoren) if...

  • Building lean muscle mass and strength
  • Improving overall body composition in aging adults
  • Enhancing athletic recovery and performance
  • Supporting metabolic health and fat loss
Capromorelin vs MK-677 (Ibutamoren) — Peptide Comparison | Peptide Initiative