Macimorelin Peptide: Benefits, Uses, Dosage

Macimorelin is a strong agonist of the GHS-R1a, which is potentially used as a diagnostic test for the adult growth hormone deficiency (AGHD).

A handful of peptides have been developed to trigger the release of growth hormone (GH) in the human body. One such tested peptide is Macimorelin, which causes the release of growth hormone (GH) naturally.

Let’s dedicate this review to macimorelin and dig into it completely so that you can decide for yourself whether you should use this peptide or not.

Warning: The content on and the information included in this article is intended for entertainment and informational purposes only. It is not intended nor implied to be a substitute for professional medical advice. Prior to buying anything, check that it is compliant where you live with your current government laws. We frequently mention research chemicals that are not made for human consumption. Therefore, before purchasing any product for personal use, consult with your doctor or healthcare provider first.

What Is Macimorelin

Growth hormone (GH) levels increase gradually during childhood, followed by a rapid surge at the time of puberty (1). It continues to be released approximately till the age of 30, after which the levels of growth hormone (GH) decline significantly.

An anomaly in the release of growth hormone (GH) either at birth (congenital) or developed later (acquired) can lead to significant changes such as slow growth, incomplete sexual development, and low stamina.

Macimorelin acetate, a synthetic growth hormone secretagogue (GHS), is chemically defined as D-Tryptophanamide, 2-methylalanyl-N-[(1R)-1-(formylamino)-2-(1H-indol-3-yl)ethyl]-acetate (2).

The pharmacokinetic study of macimorelin suggests a similar affinity to the growth hormone secretagogue receptor (GHSr) like the endogenous ligand (3).

Therefore, macimorelin binds with the specific receptors to cause an enhanced release of growth hormone (GH).

How Does Macimorelin Work

Our body produces ghrelin, which binds with growth hormone secretagogue receptors (GHSr), particularly GHS-R1a. This binding triggers the release of growth hormone (GH) from the central nervous system so that growth hormone (GH) levels are at the optimal limit.

Macimorelin, more commonly known as Macrilen, acts as an agonist for the growth hormone secretagogue receptor (GHS-R1a).

As this compound mimics the action of the endogenous ligand ghrelin, it stimulates the hypothalamus and anterior pituitary gland to cause the pulsatile release of growth hormone (GH) into the circulatory system.

Therefore, growth hormone (GH) travels to its target sites and acts in various ways to bring changes in the human body.

Benefits Of Macrimorelin

Clinical trials suggest that macrimorelin has excellent bioavailability and stability for the growth hormone secretagogue receptors (GHS-R1a) (3).

This has led to doctors approving the use of macrimorelin as a test for the adult growth hormone deficiency (AGHD) over the insulin tolerance test (ITT). The main reason is that, unlike the insulin tolerance test (ITT), macimorelin significantly minimizes the risk of developing hypoglycemia (4).

The macimorelin induced release of growth hormone (GH) offers a wide array of prospective benefits. It can act as a potential treatment in children for the problems associated with growth, such as dwarfism.

In adults, the release of growth hormone (GH) may cause a reduction in body fat while increasing the lean body mass at the same time.

Macimorelin also possesses the ability to minimize the risk of developing metabolic disorders. It can help develop glucose tolerance. It can also act as a treatment for dyslipidemia.

Macimorelin is also hypothesized to improve the cardiovascular health of individuals by keeping the heart parameters within the normal range.

Is Macimorelin Legal

The good news is YES!

Owing to successful human-based clinical trials, the food and drug authority (FDA) approved the use of macimorelin, developed by Aeterna zentaris, in December 2017 (3) .

Who Should Use Macimorelin

One of the most common uses of macimorelin is using it as a diagnostic test for adult growth hormone deficiency (AGHD).

Therefore, individuals with lower growth hormone (GH) levels can use the peptide to experience a normal growth pattern and as a potential treatment for the disorders resulting from growth hormone (GH) deficiency.

As peptides are mostly used by the bodybuilding fraternity, macimorelin can be one of the go-to peptides for bodybuilders or athletes suffering from growth hormone (GH) deficiency.

A surge in growth hormone (GH) can lead to enhanced muscle strength by speeding up the healing as well as a recovery process, and also by boosting the metabolism and burning down unnecessary fat.

How To Use Macimorelin

Since macimorelin is used as a diagnostic test for growth hormone deficiency, it is advised to be taken in front of your doctor either at a hospital or clinic.

Once the doctor has decided on your dosage guidelines, make sure to not eat or drink for at least 8 hours prior to consuming macimorelin (5).

Macimorelin is available in the market as granules (powder form) that needs to be reconstituted first. Mix the granules with water, and then within the span of 30 seconds, make sure to drink the dissolved liquid.

Your doctor then draws your blood sample after 30, 45, 60, and 90 minutes to analyze the levels of growth hormone in your circulation.

Forms Of Macimorelin

FDA only approved Macimorelin in the form of an oral intake as it is considered to have high efficacy when consumed orally.

Oral granules are available in the market by the name macrilen. Generally, the packets in the market are comprised of 60mg (6).

These granules need to be dissolved in a drink, preferably water. Once dissolved, you can drink the mixed liquid.

Macimorelin Dosage

The dosage guideline that exists worldwide is 0.5 mg per 1kg of body weight. This is because the clinical trials indicated maximum blood concentration of macimorelin when the dosage revolved around 0.5 mg/kg of body weight.

Note that it is important to fast for 8 hours before the consumption of macimorelin.

Macimorelin Cycling

This is generally consumed only as a single dose. Your healthcare professional wouldn’t ask you to go for another dose.

You will also be asked by your doctor to discontinue any other growth hormone (GH) therapy 1 week before the macimorelin administration.

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Macimorelin Experiences

I tried to find the personal experiences and insights on macimorelin but because it is not a fitness supplement/peptide that is more commonly used, there weren’t open reviews available. Also, it is more of considered as medication which makes it more tough to find reviews.

Macimorelin Side Effects

As it is an approved peptide, you don’t need to worry about severe side effects. Generally, the side effects experienced are mild enough.

These moderate side effects include:

  1. Change in taste
  2. Headache
  3. Nausea
  4. Diarrhea
  5. Fever
  6. Change in heart rhythm (detected in ECG) (7)

Where Can I Buy Macimorelin?

While most recognizable brands don’t offer macimorelin mainly because it is used more as medication or for diagnostic purposes, you would find similar peptides that trigger the release of growth hormones such as sermorelin and ipamorelin.

Brands that we vocalize with full confidence are Swiss chems  and Science. Bio.

You may want to check out similar peptides as macimorelin on these websites such as ipamorelin and sermorelin.

Macimorelin vs. Other Peptides

Macimorelin vs. ipamorelin

Both the peptides bind to the same growth hormone secretagogue receptors (GHS-R1a), but macimorelin works only by causing the release of growth hormone (GH). In contrast, ipamorelin also offers other benefits, such as suppressing the expression of somatostatin as well.

Where doctors use macimorelin to test for adult growth hormone deficiency (AGHD), ipamorelin is a banned substance.

Macimorelin vs. sermorelin

Although both peptides perform a similar function of causing the release of growth hormone (GH), sermorelin also offers other benefits, such as enhancing sleep-related circadian rhythm.

Sermorelin is quite a common peptide in the bodybuilding community, while macimorelin is more into the medication side. It requires a prescription for its purchase.

Is Macimorelin Legit?

Considering the fact that it is now a widely used diagnostic test for identifying growth hormone (GH) deficiency, I can vote for macimorelin usage for sure.

It has completed human-based clinical trials and shows prominent effects on the body, making it one of the trusted substances.

With minimal side effects observed, I believe macimorelin is definitely one of the safest peptides to cause the release of growth hormone (GH).

What is Macrilen used for?

Macrilen stimulates the release of growth hormone (GH) in the body. Macrilen is used as part of a medical diagnostic test to measure growth hormone (GH) levels.

Is macimorelin safe?

Single doses of macimorelin ranging from 0.5, 1.0, to 2.0 mg/kg were safe and well-tolerated by the users.

Is macimorelin expensive?

A 60mg oral granule of macimorelin will cost you around $4708 but the price varies depending on the pharmacy.

How do you pronounce macimorelin?

You pronounce MACRILEN (pronounced ma-kri-len) (macimorelin).

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Kumar Rathi

Kumar Rathi | Writer

Kartik is a medical student with a passion for anatomy and physiology. He writes research papers, articles and blogs to raise awareness and also has a strong interest in teaching and public speaking. Aspiring to be a successful cardiologist, Kartik believes in connecting with people on a personal level and is an expert in peptides.

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Chemical Structure

Mechanism of Action

It mimics the action of ghrelin, which is a naturally occurring endogenous ligand. Macimorelin, also known as macrilen, acts as an agonist of the growth hormone secretagogue receptor (GHS-R1a). This binding stimulates the anterior pituitary gland to release growth hormone (GH) into the circulatory system.

Class of Compound


Street Names

Macimorelin, Macrilen


It is a diagnostic test for adult growth hormone deficiency (AGHD), It stimulates the release of growth hormone (GH), Clinically proven to work

Side Effects and Dangers

May alter the normal heart rate parameters, Increases hunger, Feeling of dizziness after intake


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