Growth Hormone

Macimorelin

AEZS-130 · Macrilen · oral GH test

FDA-approved oral AGHD diagnostic (Macrilen). Single fasted dose with timed GH draws. Not MK-677, not a daily secretagogue, and this database has no SubQ vial.

WADA (S2) - prohibited in sport at all times
Reviewed by CalcMyPeptide Editorial Team
Last updated: August 2026Evidence: Moderate1 peer-reviewed citation
Typical research dose
0.5 mg/kg (diagnostic) or 1-2 mg/day (research)
Frequency
1× daily (oral)
Half-life
~4 hours (oral)
Common vials
N/A (oral)
CAS
381231-18-1
Molecular weight
492.58 g/mol

Use-case scores

0–10 against the evidence we have, not a gym ranking. Hidden domains do not apply here.

  • Sexual / hormonal7/10

    Approved diagnostic for adult GHD. Ceiling 9 for approval; haircut because this leaf is a test, not replacement therapy.

Compound card

Sequence
Oral ghrelin-mimetic peptidomimetic (AEZS-130)
Class
FDA-approved AGHD diagnostic (Macrilen); not a daily GH protocol
Formula
C26H32N6O3
Status
FDA-approved

How it works

Macimorelin (AEZS-130) is a peptidomimetic ghrelin receptor agonist - an orally active synthetic compound that mimics ghrelin binding at GHS-R1a on pituitary somatotroph cells. Unlike ghrelin itself (28 amino acids, SubQ only), macimorelin is orally bioavailable with ~90% GHS-R1a receptor selectivity.

Macimorelin is FDA-approved (Macrilen) specifically for diagnosis of adult growth hormone deficiency (AGHD). A single oral dose (0.5 mg/kg) reliably stimulates a GH peak, providing a safe, patient-friendly alternative to the insulin tolerance test (ITT) or arginine stimulation test. Off-label, it is being explored for recovery of GH axis function, though its primary use is diagnostic.

Source: FDA Label (Macrilen), PMID: 30011461

Background & History

Macimorelin is an FDA-approved oral AGHD diagnostic (Macrilen). Single fasted dose with timed GH draws. Not MK-677, not a daily secretagogue, and this database has no SubQ vial.

Research Use Cases

  • ✓Macrilen diagnostic identity vs ibutamoren
  • ✓Why a one-shot GH stim test is not a bedtime protocol
  • ✓Not a biohack oral GHRP

Dosing

PhaseDoseFrequencyNotes
Diagnostic (FDA-approved)0.5 mg/kgSingle oral dose (diagnostic only)FDA-approved for GHD diagnosis. Blood draw at baseline and 30/45/60 min post-dose. GH <2.8 ng/mL = GHD.

Administration

Route / form
Oral solution (reconstituted powder)
Timing
Fasted overnight, morning administration.
Empty stomach?
Yes - Empty stomach.

Timeline

30-60 min post-dose
Peak GH stimulation. Blood drawn for GHD diagnosis at 30, 45, and 60 min.

Who it is for

GHD Diagnosis

High

FDA-approved diagnostic agent. Replaces invasive insulin tolerance test. Single oral dose protocol.

Safety & Considerations

FDA-approved (Macrilen). Single-dose diagnostic use. Well-tolerated. May cause dizziness, nausea, or hunger (ghrelin effects). Not for therapeutic use in current approved form.

Regulatory & Legal Status

FDA Status (US)
Approved

FDA-approved as Macrilen® for diagnosis of adult growth hormone deficiency

WADA Status (2026)
Prohibited (S2)

Competitive athletes subject to anti-doping controls should not use Macimorelin.

Classification

Prescription Drug

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Limits of current evidence

  • 0.5 mg/kg once, fasted, with timed GH draws. That is the label.
  • Off-label “oral GH optimization” is not Macrilen.
  • Empty commonVialSizes. No reconstitution table.

Verdict

Macimorelin is Macrilen, a single-dose oral GH stimulation test. It is not MK-677, not a bedtime secretagogue, and this database has no daily vial. Do not force it into the SubQ calculator.

Interactions & Contraindications

Labeled fasting and CYP3A4 cautions belong to the diagnostic. Fatty meals blunt the peak. Not a chronic GH-optimization drug.

Synergies & Common Stacks

Same receptor family. Do not stack a diagnostic with a daily GHRP.

Frequently Asked Questions

What is macimorelin used for?▼
Macimorelin (Macrilen) is FDA-approved for diagnosing adult growth hormone deficiency (AGHD). A single oral dose stimulates GH release - if the peak GH response is below 2.8 ng/mL, AGHD is confirmed.
Can macimorelin be used to boost GH therapeutically?▼
Currently only FDA-approved for diagnosis. Therapeutic use is being explored but lacks approval. Other GH secretagogues like CJC-1295 or ipamorelin are typically used for therapeutic GH optimization.

References

  1. Garcia JM et al. “"Macimorelin for diagnosis of adult growth hormone deficiency".” JCEM (2018). PMID: 29272514

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