What is Macimorelin: Uses, Dosage, Side Effects and More

Macimorelin is a prescription medication that helps doctors diagnose growth hormone deficiency in adults. It works by stimulating your body to release growth hormone, which doctors can then measure through blood tests to see if your pituitary gland is working properly.

This medication comes as an oral solution that you drink, making it a more convenient option compared to older diagnostic tests that required injections. Your doctor will use macimorelin as part of a comprehensive evaluation to understand whether your body produces enough growth hormone naturally.

What is Macimorelin Used For?

Macimorelin is specifically designed to diagnose adult growth hormone deficiency (AGHD). When doctors suspect you might have this condition, they need a reliable way to test how well your pituitary gland produces growth hormone.

The medication acts as a diagnostic tool rather than a treatment. Think of it like a stress test for your pituitary gland - it challenges your body to produce growth hormone so doctors can measure the response. This helps them determine whether your symptoms are related to growth hormone deficiency or another condition.

Growth hormone deficiency in adults can cause fatigue, muscle weakness, increased body fat, and reduced quality of life. Having an accurate diagnosis is the first step toward getting the right treatment if you do have this condition.

How Does Macimorelin Work?

Macimorelin works by mimicking a natural hormone called ghrelin, which signals your pituitary gland to release growth hormone. It's considered a potent growth hormone secretagogue, meaning it's quite effective at triggering this response.

When you take macimorelin, it binds to specific receptors in your pituitary gland and hypothalamus. This binding action sends a strong signal to release growth hormone into your bloodstream. The medication reaches peak effectiveness within about 45 minutes to an hour after you take it.

Your healthcare team will draw blood samples at specific times after you take the medication to measure how much growth hormone your body produces. A normal response indicates your pituitary gland is working well, while a poor response might suggest growth hormone deficiency.

How Should I Take Macimorelin?

You'll take macimorelin as a single dose in your doctor's office or a medical facility, not at home. The medication comes as an oral solution that you drink, and the entire process requires medical supervision.

Before taking macimorelin, you'll need to fast for at least 8 hours - this means no food, but you can usually have water. Your doctor will give you specific instructions about when to stop eating and drinking before your test. This fasting period is important because food can interfere with the test results.

The medication itself tastes somewhat sweet, and you'll drink the entire dose at once. After taking it, you'll remain at the medical facility for several hours while healthcare providers draw blood samples at specific intervals to measure your growth hormone levels.

During the testing period, you'll need to stay relaxed and avoid physical activity, as exercise can also affect growth hormone levels. Your healthcare team will monitor you throughout the process to ensure you're comfortable and safe.

How Long Should I Take Macimorelin For?

Macimorelin is a one-time diagnostic test, not an ongoing treatment. You'll only take it once during your visit to the medical facility for growth hormone deficiency testing.

The entire testing process typically takes about 3-4 hours from the time you take the medication until all blood samples are collected. Most of this time involves waiting between blood draws rather than any active treatment.

If your doctor needs to repeat the test for any reason, they'll schedule a separate appointment. However, most people only need this test done once to get a clear picture of their growth hormone status.

What Are the Side Effects of Macimorelin?

Most people tolerate macimorelin well, but like any medication, it can cause side effects. The most common ones are generally mild and temporary, occurring during or shortly after the test.

Here are the side effects you might experience during or after taking macimorelin:

• Nausea or feeling queasy
• Dizziness or lightheadedness
• Headache
• Fatigue or tiredness
• Increased hunger
• Changes in taste
• Mild stomach discomfort

These common side effects usually resolve on their own within a few hours. The medical team monitoring your test will watch for these reactions and can help you feel more comfortable if they occur.

While rare, some people might experience more significant side effects that require immediate medical attention. These serious reactions are uncommon but important to recognize:

• Severe dizziness or fainting
• Rapid or irregular heartbeat
• Difficulty breathing
• Severe nausea or vomiting
• Allergic reactions like rash, itching, or swelling

Since you'll be in a medical facility during the test, healthcare providers can quickly address any concerning symptoms that might arise. This supervised setting ensures your safety throughout the diagnostic process.

Who Should Not Take Macimorelin?

Certain people should avoid macimorelin due to safety concerns or the risk of inaccurate test results. Your doctor will review your medical history carefully before recommending this test.

You should not take macimorelin if you have any of these conditions:

• Known allergy to macimorelin or its ingredients
• Severe liver problems or active liver disease
• Severe kidney disease
• Recent heart attack or unstable heart conditions
• Uncontrolled high blood pressure
• Active pituitary tumors

Pregnancy and breastfeeding also require special consideration, as the safety of macimorelin hasn't been established in these situations. Your doctor will discuss alternative testing options if you're pregnant or nursing.

Certain medications can interfere with macimorelin's effectiveness or safety. Be sure to tell your doctor about all medications you're taking, including:

• Growth hormone supplements
• Corticosteroids
• Medications that affect heart rhythm
• Blood pressure medications
• Diabetes medications

Your healthcare provider will help determine if macimorelin is safe and appropriate for your specific situation. They might recommend alternative testing methods if you have any contraindications.

Macimorelin Brand Names

Macimorelin is available under the brand name Macrilen in the United States. This is currently the only commercially available form of this medication.

Macrilen is manufactured by Aeterna Zentaris and was specifically developed for diagnosing adult growth hormone deficiency. Your doctor will refer to it by either name - macimorelin or Macrilen - and they mean the same medication.

Since this is a specialized diagnostic medication, it's only available through healthcare facilities that perform growth hormone testing. You won't find it at regular pharmacies because it requires medical supervision during administration.

Macimorelin Alternatives

Several other tests can diagnose growth hormone deficiency, though each has its own advantages and limitations. Your doctor will choose the best option based on your specific situation and medical history.

The insulin tolerance test (ITT) is considered the gold standard for diagnosing growth hormone deficiency. However, it requires careful monitoring because it involves deliberately lowering your blood sugar, which can be uncomfortable and potentially dangerous for some people.

The arginine stimulation test is another alternative that's generally safer than ITT. Arginine is an amino acid that stimulates growth hormone release, but it's not as potent as macimorelin and may not work as well in all patients.

The glucagon stimulation test offers another option, particularly for people who can't safely undergo insulin tolerance testing. Glucagon is a hormone that indirectly stimulates growth hormone release, though it may cause nausea more commonly than macimorelin.

Your doctor will consider factors like your age, overall health, other medical conditions, and previous test results when choosing the most appropriate diagnostic approach for you.

Is Macimorelin Better Than Other Growth Hormone Tests?

Macimorelin offers several advantages over traditional growth hormone tests, making it a preferred choice in many situations. It's generally safer and more comfortable than some alternatives while providing reliable results.

Compared to the insulin tolerance test, macimorelin is much safer because it doesn't risk causing dangerously low blood sugar. The insulin test can be particularly risky for people with heart disease, seizure disorders, or diabetes, while macimorelin is safe for most people.

Macimorelin is also more convenient than injection-based tests. You simply drink the medication rather than receiving shots, which many people find more comfortable. The oral route also eliminates concerns about injection site reactions or needle-related anxiety.

The test provides results that are just as reliable as traditional methods. Studies show that macimorelin accurately identifies growth hormone deficiency with high sensitivity and specificity, meaning it correctly identifies both people who have the condition and those who don't.

However, macimorelin isn't automatically better for everyone. Some people might still need alternative tests based on their specific medical conditions or if initial results are unclear. Your doctor will help determine which test is most appropriate for your individual situation.