What does Macimorelin do?

Macimorelin, sold under the brand name Macrilen, is described as an oral diagnostic agent for adult growth hormone deficiency. The supplied evidence frames it as a one-time test used to assess pituitary growth hormone release, not as a treatment.

How does Macimorelin work?

The source describes macimorelin as a ghrelin-mimicking peptidomimetic that activates the growth hormone secretagogue receptor on the anterior pituitary. After oral administration, blood growth hormone measurements over about 90 minutes are used to evaluate whether the pituitary response is normal or blunted.

Is Macimorelin FDA approved?

Yes. The supplied evidence lists macimorelin as FDA approved, with the clinical status specified as a diagnostic for adult growth hormone deficiency. The source notes approval in December 2017.

What side effects are reported for Macimorelin?

Reported adverse effects in the source include taste changes or dysgeusia, dizziness, headache, nausea, and QT prolongation. The research summary also flags QT prolongation as relevant when considering other QT-prolonging drugs.

What dose information is reported for Macimorelin?

The extracted community field says limited community data are available and refers to research dosing. The research row lists 0.5 mg/kg as a single oral dose for an FDA-approved diagnostic protocol, with oral solution and fasting administration noted.

This entry is not a peptide · It is included because this compound is commonly discussed alongside peptide research.

Hormonal FDA Approved - approved for specific uses

Macimorelin

Also known as: Macrilen, AEZS-130

At a glance

PeptiGuide dataset · reviewed Aug 2026

What it is

FDA-approved oral ghrelin receptor agonist used for adult growth hormone deficiency diagnosis.

Status

FDA Approved

Evidence level: human clinical evidence

Typical dose

Limited community data available

Oral solution

Researched for

GH deficiency diagnosis, hormone testing

Trial progress

PrePreclinical
IPhase I
IIPhase II
IIIPhase III
IVPhase IV
FDAFDA approved

FDA approved - FDA-approved for specific uses with established human evidence

Use the tools

In plain language

Macimorelin, also known as Macrilen or AEZS-130, is an FDA-approved oral diagnostic agent for adult growth hormone deficiency.
The source frames it as a diagnostic test, not a treatment, performance compound, or anti-aging agent.
Reported research dosing is 0.5 mg/kg as a single oral dose; the community dose field says limited community data are available.
Administration is listed as oral solution, fasting, while a separate food field says with or without food.
Reported side effects include dysgeusia, dizziness, headache, nausea, and QT prolongation.

How it's thought to work

Macimorelin is described as a peptidomimetic small molecule that imitates ghrelin signaling. It targets the growth hormone secretagogue receptor, also called the ghrelin receptor, on the anterior pituitary. Activation of that receptor produces a measurable growth hormone response, and blood sampling over 90 minutes helps distinguish a normal pituitary response from a blunted response in adult growth hormone deficiency evaluation.

What the research shows

Where the research stands

The supplied research summary describes macimorelin approval evidence as a head-to-head validation against the insulin tolerance test, a prior reference method that intentionally lowers blood glucose. In that comparison, the macimorelin test was reported to identify adult growth hormone deficiency in about 87% of affected people and to clear people without the condition in about 98% of cases. The described protocol used one oral dose, four blood draws, and no IV insulin. The same source notes QT prolongation as a caution and states that macimorelin is not validated for performance enhancement or anti-aging use despite its ghrelin-receptor activity.

What it shows

✓ Human clinical evidence

FDA-approved for specific uses with established human evidence

△ Limitations

Use only according to approved labeling and qualified medical guidance.

Bottom line: FDA approved diagnostic for adult growth hormone deficiency FDA Approved

Typical dosing

CommunityCommunity dataset

Limited community data available

See research protocols

Range: See research dosing

Community-reported dosing data are limited and point back to research protocols; this row is retained as source evidence and is not dosing guidance.

Research dosing

Indication-specificApproved for specific uses - study doses are indication-specific

Doses observed in studies

0.5 mg/kg oral single dose

FDA Approved Labeling - Prescribed dose

Use only according to approved labeling and qualified medical guidance.

Duration: Single diagnostic test
Administration: Oral solution, fasting

Timing & administration

Best time to take

Morning or as directed

Follow recommended protocol

Food recommendation

With or without food

Why this timing?

The source gives only general timing language: timing may vary, and consistent protocol-following is emphasized over a specific clock time.

Possible side effects

Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.

Taste changes (dysgeusia)
Dizziness
Headache
Nausea
QT prolongation

Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.

Sources

PubMed ClinicalTrials.gov FDA.gov

Frequently asked questions

Sequence

Aib-D-Trp-D-gamma-Trp-CHO

One open dataset

Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.

Browse the dataset

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Educational resource, not medical advice. Talk to your clinician before acting on anything here.

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Macimorelin

In plain languageIn plain language

How it's thought to workHow it's thought to work

What the research showsWhat the research shows

Typical dosing

Research dosing

Timing & administrationTiming & administration

Possible side effectsPossible side effects

SourcesSources

Frequently asked questionsFrequently asked questions