Ibutamoren vs Macimorelin

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

Research Score

PropertyIbutamorenMacimorelin
CategoryGrowth HormoneGrowth Hormone
Full NameIbutamoren mesylate (MK-677)Macimorelin acetate (AEZS-130)
Molecular WeightN/AN/A
Half-Lifeabout 24 hoursabout 4-6 hours
Amino AcidsN/AN/A
Typical Dose10-25 mg/day0.5 mg/kg single oral dose
RouteOralOral
Purity≥98%≥98%
Studies Count180120
Research StatusClinicalClinical

Ibutamoren Benefits

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

Macimorelin Benefits

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

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 Dosing

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

Ibutamoren Side Effects

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

Macimorelin Side Effects

  • dysgeusia or taste disturbance
  • nausea
  • headache

Research Overview

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.

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.

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Common Stacking Partners

Ibutamoren stacks with:

Resistance trainingHigh-protein diet

Macimorelin stacks with:

Pituitary testingEndocrine workup
ghrelin-receptor-agonistgh-secretagogueoraldiagnosticghrelin-mimeticgh-stimulation-test