Macimorelin (Macrilen)_Dosage, benefits & legal status
Also known as Macrilen, AEZS-130, macimorelin acetate
An FDA-approved ghrelin agonist, and it is a diagnostic test rather than a treatment.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Macimorelin (Macrilen)?
Plain language first. The technical label stays, but it never stands alone.Overview
The one ghrelin drug the FDA approved, and it is a one-off test rather than a treatment. It replaced an older test that worked by deliberately crashing your blood sugar.
Macimorelin acetate, an orally active growth hormone secretagogue receptor agonist, FDA-approved in December 2017 as an oral diagnostic test for adult growth hormone deficiency. Administered as a single 0.5 mg/kg reconstituted oral solution after at least eight hours fasting, with timed post-dose growth hormone sampling. Strong CYP3A4 inducers may produce false positive results.
What it's used for
A single-dose oral test for diagnosing adult growth hormone deficiency.
How does Macimorelin (Macrilen) work?
What it does in the body, and where.Macimorelin is the answer to a question people ask about the GHRP family: has any of this been approved for anything.
- 01It provokes a growth hormone pulse on purposeAs a ghrelin receptor agonist it triggers the pituitary to release growth hormone. Blood samples taken afterward show whether the gland can respond.
- 02It replaced an unpleasant older testThe insulin tolerance test was the reference standard, and it works by deliberately inducing low blood sugar under supervision. It is contraindicated in people with heart disease or seizure disorders. An oral alternative with comparable accuracy is a real improvement.
- 03One dose, onceThe label specifies a single oral dose of 0.5 mg per kilogram as a reconstituted solution after at least eight hours fasting. There is no repeat schedule because it is not a therapy.
- 04Drug interactions can produce a false resultThe label warns that strong CYP3A4 inducers can lower macimorelin levels and cause false positives, and that drugs affecting growth hormone secretion should be avoided around the test.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
- Diagnosis of adult growth hormone deficiencyFDA-approved
- Raising growth hormone as a treatment, which is not what it is approved fornone
The published record
Papers and trials about Macimorelin (Macrilen)
32 papers tagged human · 18 not reviews or lab · 4 clinical trial publications
6 registered trials · 3 with posted results
Furthest stage reached: Approved in the US
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Prohibited at all times, in and out of competition. S2.2.4 Growth hormone releasing factors: growth hormone secretagogues (GHS) and their mimetics (macimorelin named). Non-Specified.RegulatorsCounted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Macimorelin (Macrilen)
Evidence
FDA-approved
Category
Growth hormone
Common vial
Varies
Half-life
About 4 hours
How much, and do you cycle it?
The range, and whether you take breaks.0.5 mg per kg, once, single dose for the test. Set by the prescription FDA label
This is a prescription drug. Duration and schedule are set by the label and the prescriber, not by a cycling convention.
About 4 hoursFDA label
Measured after a single oral dose in healthy subjects. Macimorelin is broken down mainly by the liver enzyme CYP3A4, so other drugs using the same pathway can change how long it lasts.
Source: Macrilen label section 12.3, DailyMed setid 6034c9b8-5a36-4961-a5dd-11ebf7bdab78
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.A single oral dose of 0.5 mg per kilogram, given as a reconstituted solution after at least eight hours fasting. This is a diagnostic dose, not a treatment dose.
How do you store it?
Before mixing, and after.Room temperature. Cool, dry, out of light.
Macimorelin (Macrilen) is taken as a pill or capsule. Keep it in its original container at room temperature, away from heat, humidity, and direct sun. No fridge or mixing needed. Check the expiration date on the bottle.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Pregnancy or breastfeeding, where the test has not been established
- Use as a growth hormone treatment, which is not an approved use
- Taking strong CYP3A4 inducers, which the label says should be stopped before the test
Stop and get help
- Signs of an allergic reaction, including facial or throat swelling or trouble breathing
- Palpitations or an irregular heartbeat
Common effects
- A temporary metallic or bitter taste, reported in the trials
- Headache
- Tiredness
- Nausea
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Macimorelin (Macrilen) approved?
And where the numbers on this page come from.Yes. Macimorelin (Macrilen) is FDA approved and available on prescription in the United States.
- Approval statusFDA-approved
- RouteBy mouth (oral)
- Checked24 August 2026
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesNone traced yet.
What has happened recently
FDA-approved in December 2017 as an oral diagnostic for adult growth hormone deficiency. Prohibited in sport at all times by WADA, which names macimorelin explicitly. Drug availability listings indicate the marketed formulations have been discontinued, which is separate from the approval remaining on record.
What regulators say
From official documentsProhibited at all times, in and out of competition. S2.2.4 Growth hormone releasing factors: growth hormone secretagogues (GHS) and their mimetics (macimorelin named). Non-Specified.
Checked 12 September 2026WADA: The 2026 Prohibited List (in force 1 January 2026)
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
What else is like Macimorelin (Macrilen)?
Others in Growth hormone peptides, side by side.If you're weighing Macimorelin (Macrilen), it's worth reading Relamorelin, Tesamorelin, and Ipamorelin in the same class.
An FDA-approved ghrelin agonist, and it is a diagnostic test rather than a treatment.
- Dose
- 0.5 mg per kg, once
- How often
- Single dose for the test
A ghrelin mimic tested in 1,564 people with diabetic gastroparesis, then stopped before any filing.
- Dose
- 10 mcg twice daily (phase 3); 10 to 100 mcg in earlier trials
- How often
- Twice daily (gastroparesis trials)
An approved shot proven to shrink stubborn belly fat.
- Dose
- 1.28 up to 2 mg per day, depending on which product you have
- How often
- Daily
A gentle shot that nudges your body to release its own growth hormone.
- Dose
- 0.2 up to 0.3 mg per dose (start low, increase slowly)
- How often
- Daily, often at night
Guides for this compound
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
No primary source has been traced for this compound yet. Treat everything on this page as unverified until one is. How we grade evidence
Beyond these, 45 records are indexed. Browse the records