Macimorelin vs Ibutamoren

Head-to-head comparison of Macimorelin (Macimorelin acetate (AEZS-130)) and Ibutamoren (Ibutamoren mesylate (MK-677)) — benefits, dosing, side effects, research data, and where to buy.

Research Score

PropertyMacimorelinIbutamoren
CategoryGrowth HormoneGrowth Hormone
Full NameMacimorelin acetate (AEZS-130)Ibutamoren mesylate (MK-677)
Molecular WeightN/AN/A
Half-Lifeabout 4-6 hoursabout 24 hours
Amino AcidsN/AN/A
Typical Dose0.5 mg/kg single oral dose10-25 mg/day
RouteOralOral
Purity≥98%≥98%
Studies Count120180
Research StatusClinicalClinical

Macimorelin Benefits

  • diagnostic GH stimulation
  • single oral dose
  • rapid measurable GH response
  • high clinical utility

Ibutamoren Benefits

  • raises GH/IGF-1
  • increases appetite
  • supports lean mass retention
  • oral non-peptide secretagogue

Macimorelin Dosing

0.5 mg/kg orally as a single dose|fasted testing conditions|serial GH sampling after administration

Ibutamoren Dosing

10-25 mg orally once daily|take consistently at the same time each day|monitor fasting glucose and edema in longer studies

Macimorelin Side Effects

  • dysgeusia or taste disturbance
  • nausea
  • headache

Ibutamoren Side Effects

  • increased appetite
  • water retention/edema
  • somnolence or lethargy

Research Overview

Macimorelin

Macimorelin has been validated in clinical testing as an oral alternative to injectable GH stimulation tests. Its short-term use makes it a useful translational tool for evaluating pituitary GH reserve.

Ibutamoren

Clinical studies show oral ibutamoren reliably elevates GH and IGF-1 over 24 hours with once-daily dosing. Body composition and appetite effects vary by population, and development has been limited by metabolic side effects.

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Common Stacking Partners

Macimorelin stacks with:

Pituitary testingEndocrine workup

Ibutamoren stacks with:

Resistance trainingHigh-protein diet
diagnosticghrelin-mimeticgh-stimulation-testghrelin-receptor-agonistgh-secretagogueoral