Macimorelin

Overview

The only orally administered growth hormone secretagogue with full FDA approval — and it is approved as a diagnostic test, taken once, not as a therapy. That distinction is the whole point of including it.

How it works

Ghrelin receptor agonism producing a reliable, reproducible growth hormone pulse. Its diagnostic value rests on that reproducibility: a peak GH below a defined threshold after a single oral dose confirms adult GH deficiency.

Evidence base

Rated 5 of 5 — Very strong. Multiple phase 3 randomized trials plus regulatory approval in a major market.

• Head-to-head validation against the previous reference standard — the right trial design for a diagnostic.

Benefits & potential uses

Bars indicate how well each claim is supported: three = strong human evidence, two = moderate, one = preliminary or preclinical.

• Replaces a genuinely dangerous test Strong evidence

  The insulin tolerance test requires deliberately inducing hypoglycemia under supervision and is contraindicated in cardiac disease and epilepsy. Macimorelin achieves comparable diagnostic accuracy with an oral solution.

• High diagnostic agreement Strong evidence

  The pivotal trial showed sensitivity and specificity closely matching the insulin tolerance test.

• Oral and outpatient Strong evidence

  No infusion, no induced hypoglycemia, no intensive monitoring.

• Proves oral GH secretagogues are feasible Moderate evidence

  A useful reference point when assessing unapproved oral secretagogue claims.

Risks, cons & cautions

Bars indicate seriousness: three = serious or common, two = moderate, one = minor.

• Diagnostic use only Serious

  It is not a treatment. There is no evidence base for repeated dosing, and no approval for therapeutic use.

• QT interval prolongation Serious

  The main safety concern; concurrent QT-prolonging drugs must be stopped before testing.

• Dysgeusia Minor

  A distorted or metallic taste is the most common adverse effect.

• False results with interfering drugs Moderate evidence

  Strong CYP3A4 inducers and recent GH therapy can invalidate the test.

• Fatigue and headache Minor

  Reported after the single dose.

Who should avoid it

• Concurrent QT-prolonging medication
• Known congenital long QT syndrome
• Use as a therapy rather than a diagnostic

If used under medical supervision, monitor

• ECG before testing where QT risk exists
• Serial GH sampling per the test protocol
• Review of interfering medications

Interactions

Not exhaustive. Always have a pharmacist or physician review your full medication list — including supplements.

• QT-prolonging drugs — must be discontinued before testing
• Strong CYP3A4 inducers — can cause false results
• Recent growth hormone therapy — invalidates the test

Commonly confused with

These mix-ups cause real harm — two products sold under one name, or two molecules whose effects run in opposite directions.

Regulatory & legal status

Prescription diagnostic agent, administered under medical supervision.

Infographic

Macimorelin — benefits & risks at a glance Download SVG

Where to read further

We link to live literature searches rather than a frozen citation list, so you always see current results — including anything published after our last review.

• PubMed — all published literature on Macimorelin
• PubMed — randomized controlled trials only
• ClinicalTrials.gov — registered human trials
• DailyMed — official FDA prescribing information

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