GHRYVELIN (Macimorelin)
Diagnostic Oral Suspension for Testing Adult Growth Hormone Deficiency
Quick Facts About GHRYVELIN
Key Takeaways
- GHRYVELIN (macimorelin) is a single-dose oral diagnostic test used to evaluate growth hormone deficiency in adults — it is not a treatment.
- You must fast for at least 8 hours and avoid strenuous exercise for 24 hours before the test for accurate results.
- Blood samples are taken at 45, 60, and 90 minutes after drinking the suspension to measure growth hormone response.
- Common side effects are mild and temporary: bitter taste, fatigue, headache, nausea, and dizziness.
- GHRYVELIN may cause transient QT prolongation on ECG; inform your doctor if you have any heart rhythm disorder or are taking medications that affect heart rhythm.
What Is GHRYVELIN and What Is It Used For?
Quick Answer: GHRYVELIN (macimorelin) is an oral diagnostic agent that stimulates the pituitary gland to release growth hormone. It is used as a single-dose test to help doctors diagnose adult growth hormone deficiency (AGHD).
GHRYVELIN contains the active substance macimorelin, a synthetic compound that mimics the natural hormone ghrelin. Ghrelin, sometimes called the "hunger hormone," is produced primarily in the stomach and plays a key role in stimulating the pituitary gland — a small, pea-sized gland at the base of the brain — to secrete growth hormone (GH) into the bloodstream. By activating the same receptor as natural ghrelin (the growth hormone secretagogue receptor, GHS-R1a), macimorelin triggers the release of growth hormone in a predictable and measurable way.
Growth hormone is essential for many physiological processes throughout life, not just during childhood growth. In adults, GH regulates body composition, metabolism, bone density, muscle mass, cardiovascular health, and overall quality of life. When the pituitary gland fails to produce sufficient growth hormone, the condition is known as adult growth hormone deficiency (AGHD). This condition can arise from damage to the pituitary gland or the hypothalamus caused by tumours, surgery, radiation therapy, traumatic brain injury, or other diseases.
Diagnosing AGHD requires a stimulation test — a procedure in which a pharmacological agent provokes the pituitary gland to release GH, and blood samples are then analysed to see whether the hormone response reaches adequate levels. GHRYVELIN is approved specifically for this purpose. Unlike traditional stimulation tests that require intravenous injections (such as the insulin tolerance test), GHRYVELIN is taken orally, making the procedure less invasive and more convenient for patients.
The European Medicines Agency (EMA) has authorised GHRYVELIN for use in adults. Clinical studies have demonstrated that the macimorelin stimulation test has high diagnostic accuracy, with sensitivity and specificity comparable to the insulin tolerance test (ITT), which has traditionally been considered the gold standard for GHD diagnosis. However, unlike the ITT, the macimorelin test does not carry the risk of severe hypoglycaemia, making it a safer alternative for many patients.
What Should You Know Before Taking GHRYVELIN?
Quick Answer: Do not take GHRYVELIN if you are allergic to macimorelin or any of its ingredients. Fasting for at least 8 hours and avoiding strenuous exercise for 24 hours before the test are essential for reliable results. Inform your doctor about all medications you are taking, especially those affecting heart rhythm or hormone levels.
Contraindications
You should not be given GHRYVELIN if you are allergic (hypersensitive) to macimorelin or any of the other ingredients in the medicine. If you are unsure whether you have any allergies that may apply, speak to your doctor or nurse before the test is administered.
Warnings and Precautions
For the test results to be reliable and clinically meaningful, strict preparation is necessary. These preparation rules are not optional — failure to follow them can lead to false results, potentially resulting in a missed diagnosis or an incorrect one.
- Fasting: You must not eat for at least 8 hours before the test and throughout the duration of the test itself. Food intake can interfere with growth hormone levels and affect the accuracy of results.
- Physical activity: Avoid strenuous exercise for 24 hours before the test. Intense physical exertion can artificially elevate growth hormone levels, leading to misleading results.
- Fluid intake: You may drink up to 100 ml of still (non-carbonated) water within 1 hour before and 1 hour after taking the suspension. No other beverages are permitted.
Inform your doctor or nurse before the test in the following circumstances:
- Growth hormone therapy: If you have recently been treated with growth hormone (somatotropin) or with medicines that affect the pituitary gland's secretion of growth hormone, you must stop this treatment at least 1 month before the test. Continuing such therapy can mask true GHD and produce inaccurate results.
- Cushing's disease: If you have recently been treated for Cushing's disease (a condition characterised by excessive cortisol production) or if you are receiving high-dose hydrocortisone therapy, the test may produce false positive results. Elevated cortisol levels can suppress the pituitary's GH response independently of true GHD.
- Other hormonal deficiencies: If your body lacks other hormones — such as cortisol, thyroid-stimulating hormone (TSH), sex hormones, or vasopressin (in diabetes insipidus) — these should ideally be replaced before the GHRYVELIN test. Untreated deficiencies in these hormones can interfere with the growth hormone stimulation response and produce unreliable results.
- Heart conditions: If you have a heart disease, problems with your heart rhythm (including congenital or acquired long QT syndrome), or a history of torsades de pointes, inform your doctor. GHRYVELIN can cause changes on the electrocardiogram (ECG), including QT prolongation, which is associated with an increased risk of abnormal heart rhythm. These changes are transient and short-lived, but monitoring may be required in susceptible individuals.
GHRYVELIN is a single-dose diagnostic test. There is no available safety and efficacy data for repeated or long-term use. If the growth hormone deficiency has developed recently due to a hypothalamic injury, the initial test result may be negative despite the presence of the condition. In such cases, your doctor may recommend repeating the test at a later time.
Children and Adolescents
GHRYVELIN must not be given to children and adolescents under 18 years of age. The safety and efficacy of macimorelin have not been established in these age groups. Diagnostic testing for growth hormone deficiency in children requires different methodologies and age-appropriate protocols established by paediatric endocrinologists.
Pregnancy and Breastfeeding
GHRYVELIN is not recommended during pregnancy. If you are a woman of childbearing potential, you must use effective contraception to ensure that you are not pregnant at the time of the test. The safety of macimorelin for use during pregnancy has not been established, and potential risks to the developing foetus cannot be ruled out.
If you are breastfeeding or intend to breastfeed, a risk to the nursing infant cannot be excluded. Discuss with your doctor whether to discontinue breastfeeding or postpone the macimorelin test. The decision should take into account the importance of the diagnostic procedure for your health.
Driving and Using Machines
Dizziness is a known side effect of GHRYVELIN. If you experience dizziness after the test, do not drive or operate machinery until the symptom has resolved completely. Plan for someone to drive you home if needed.
Important Information About Ingredients
GHRYVELIN contains lactose. If you have been told by your doctor that you have an intolerance to certain sugars, speak to your doctor before taking this medicine.
GHRYVELIN contains less than 1 mmol sodium (23 mg) per sachet, which means it is essentially sodium-free. This is relevant for patients on sodium-restricted diets.
How Does GHRYVELIN Interact with Other Drugs?
Quick Answer: GHRYVELIN interacts with medications that affect heart rhythm (QT-prolonging drugs), drugs that increase its metabolism (CYP3A4 inducers), and medicines that directly affect growth hormone secretion. Inform your doctor about all medications you are taking.
Drug interactions with GHRYVELIN can be divided into three categories: those that affect cardiac safety, those that alter how the body processes macimorelin, and those that can influence the accuracy of the diagnostic test result. It is critical to disclose all medications — including over-the-counter medicines and herbal supplements — to your healthcare provider before the test.
Drugs That Affect Heart Rhythm (QT-Prolonging Agents)
Because GHRYVELIN can cause transient QT prolongation, concurrent use with other QT-prolonging medications increases the risk of cardiac arrhythmias. Inform your doctor if you are taking any of the following:
| Drug Category | Examples | Risk Level |
|---|---|---|
| Antipsychotics | Chlorpromazine, haloperidol | Major — increased QT risk |
| Antibiotics | Erythromycin, clarithromycin, moxifloxacin | Major — increased QT risk |
| Antiarrhythmics | Amiodarone, procainamide, quinidine, sotalol | Major — increased QT risk |
Drugs That Increase Macimorelin Metabolism (CYP3A4 Inducers)
Macimorelin is metabolised primarily by the CYP3A4 enzyme in the liver. Drugs that induce (speed up) this enzyme can decrease macimorelin blood levels, potentially leading to a suboptimal growth hormone stimulation and a false positive result (i.e., a diagnosis of GHD when the patient may not actually have it). Inform your doctor if you are taking any of the following:
| Indication | Drug Examples | Effect on Test |
|---|---|---|
| Epilepsy / seizures | Carbamazepine, eslicarbazepine, fosphenytoin, oxcarbazepine, phenobarbital, phenytoin, primidone | May reduce macimorelin levels |
| Sleep disorders | Modafinil, pitolisant | May reduce macimorelin levels |
| Mild depression | St. John's wort (Hypericum perforatum) | May reduce macimorelin levels |
| Cystic fibrosis | Lumacaftor | May reduce macimorelin levels |
| Infections | Rifabutin, rifampicin | May significantly reduce macimorelin levels |
| HIV | Efavirenz, nevirapine | May reduce macimorelin levels |
| Type 2 diabetes | Pioglitazone | May reduce macimorelin levels |
| Cancer | Dabrafenib, enzalutamide | May reduce macimorelin levels |
Drugs That May Affect Diagnostic Test Accuracy
Certain medications can interfere directly with the pituitary's growth hormone secretion or alter the body's GH response to macimorelin, leading to unreliable test results. Avoid concurrent use with:
- Drugs that directly affect pituitary GH secretion: Somatostatin, insulin, glucocorticoids, acetylsalicylic acid (aspirin), indomethacin
- Drugs that may increase GH levels: Clonidine, levodopa, insulin — these could mask true GHD by artificially boosting the GH response
- Drugs that may decrease the GH response to macimorelin: Atropine, propylthiouracil, growth hormone medications — these could produce a false positive (apparent GHD) result
What Is the Correct Dosage of GHRYVELIN?
Quick Answer: The dose is 0.5 mg of GHRYVELIN per kilogram of body weight, administered as an oral suspension. This corresponds to 1 ml of prepared suspension per kg of body weight. The entire dose must be consumed within 30 seconds.
Adults
GHRYVELIN must be prepared and administered under the supervision of healthcare professionals in a clinical setting. The dosing procedure follows a carefully standardised protocol to ensure accurate diagnostic results.
Standard Adult Dose
Dose: 0.5 mg macimorelin per kg body weight
Preparation: One sachet (60 mg) dissolved in 120 ml of water for patients up to 120 kg. Two sachets dissolved in 240 ml for patients over 120 kg.
Volume to administer: 1 ml of prepared suspension per kg body weight (e.g., a 70 kg patient receives 70 ml)
Administration: Drink the entire dose within 30 seconds
Use within: 30 minutes of preparation
The test procedure involves the following steps:
- Weigh the patient to determine the precise dose required.
- Prepare the suspension by dissolving the contents of the sachet(s) in the appropriate volume of tap water. Stir gently for 2 minutes until the suspension is slightly cloudy. A few undissolved particles may remain, which is normal.
- Measure the required volume using a graduated syringe (without needle). Transfer the measured volume to a drinking glass.
- The patient drinks the entire contents of the glass within 30 seconds.
- Blood samples are collected at 45, 60, and 90 minutes after ingestion to measure growth hormone levels.
- Samples are sent to a laboratory for growth hormone analysis.
Children
GHRYVELIN is not approved for use in children and adolescents under 18 years of age. The safety and efficacy of this diagnostic agent have not been established in the paediatric population. Growth hormone deficiency testing in children requires specialised protocols under the guidance of a paediatric endocrinologist.
Elderly
No specific dose adjustment is required for elderly patients. The standard weight-based dose of 0.5 mg/kg applies. However, elderly patients may be more likely to have cardiac conditions or to be taking QT-prolonging medications, so additional cardiac monitoring may be warranted during the test.
Missed Dose
GHRYVELIN is administered as a single-dose diagnostic test under medical supervision in a clinical setting. A missed dose scenario does not apply. If the test needs to be rescheduled, your healthcare provider will arrange a new appointment with appropriate fasting instructions.
Overdose
If you have been given too much GHRYVELIN, inform your doctor or nurse immediately. Potential symptoms of overdose may include headache, nausea, vomiting, and diarrhoea. If cardiac rhythm disturbances occur, ECG monitoring will be performed. As GHRYVELIN is always administered under medical supervision, overdose is unlikely but remains a possibility that healthcare staff are trained to manage.
What Are the Side Effects of GHRYVELIN?
Quick Answer: The most common side effects of GHRYVELIN are bitter or metallic taste, tiredness, headache, nausea, dizziness, diarrhoea, and a sensation of warmth. These are typically mild, short-lived, and resolve quickly without treatment.
Like all medicines, GHRYVELIN can cause side effects, although not everybody gets them. Because GHRYVELIN is a single-dose diagnostic agent, side effects tend to be brief and self-limiting. Most adverse reactions occur within the first hour after administration and resolve within a few hours.
Common
May affect up to 1 in 10 people
- Bitter or metallic taste in the mouth (dysgeusia)
- Tiredness (fatigue)
- Headache
- Nausea
- Dizziness
- Diarrhoea
- Sensation of warmth (flushing)
Uncommon
May affect up to 1 in 100 people
- Abdominal pain
- Feeling cold
- Hunger
- Palpitations (sensation of a rapid or pounding heartbeat)
- Slower-than-normal heart rate (sinus bradycardia)
- Drowsiness (somnolence)
- Thirst
- Tremor (shaking)
- Vertigo (a spinning sensation)
Frequency Not Known
Reported but frequency cannot be estimated
- Changes on the electrocardiogram (ECG), including QT prolongation
The bitter or metallic taste is the most frequently reported side effect and is related to the properties of the macimorelin compound itself. It typically lasts only a few minutes after ingestion. Fatigue and headache generally resolve within 1–2 hours.
The ECG changes (QT prolongation) that have been reported are transient and do not persist beyond the duration of the test. Healthcare professionals performing the test are trained to recognise and manage any cardiac-related events, although clinically significant arrhythmias have not been reported in clinical trials.
How Should You Store GHRYVELIN?
Quick Answer: Store unopened GHRYVELIN sachets in a refrigerator (2–8°C) in the original packaging to protect from light and moisture. The prepared suspension must be used within 30 minutes.
Proper storage of GHRYVELIN is essential to ensure the medicine remains effective and safe for use. The following storage conditions apply:
- Unopened sachets: Store in a refrigerator at 2–8°C (36–46°F). Keep in the original packaging to protect from light and moisture. The shelf life of an unopened sachet is 4 years from the date of manufacture.
- Prepared suspension: Once dissolved in water, the suspension must be administered within 30 minutes. Do not store the prepared suspension. Any remaining suspension must be discarded by healthcare staff in accordance with local disposal regulations.
- Expiry date: Do not use GHRYVELIN after the expiry date stated on the outer carton and sachet (after "EXP"). The expiry date refers to the last day of that month.
Keep this medicine out of the sight and reach of children. Do not throw away medicines via wastewater or household waste. These measures help to protect the environment.
What Does GHRYVELIN Contain?
Quick Answer: Each GHRYVELIN sachet contains 60 mg of macimorelin (as acetate) along with inactive ingredients including lactose monohydrate, colloidal anhydrous silica, crospovidone, saccharin sodium, and sodium stearyl fumarate.
Active Ingredient
Each sachet contains 60 mg of macimorelin (as macimorelin acetate). When the granules are dissolved as directed, 1 ml of the prepared suspension contains 500 micrograms (0.5 mg) of macimorelin.
Inactive Ingredients (Excipients)
- Lactose monohydrate — a sugar used as a filler and binder. Patients with lactose intolerance should consult their doctor.
- Colloidal anhydrous silica — an anti-caking agent that ensures uniform granule consistency.
- Crospovidone type A — a disintegrant that helps the granules dissolve when mixed with water.
- Saccharin sodium dihydrate — an artificial sweetener to improve palatability.
- Sodium stearyl fumarate — a lubricant used in the manufacturing process.
Appearance and Packaging
GHRYVELIN comes as white to off-white granules for oral suspension. Each sachet contains 1,817 mg of granules. Each carton contains one single-dose sachet. The granules are not intended to be swallowed directly — they must first be dissolved in water as directed by your healthcare professional to prepare the suspension.
Frequently Asked Questions About GHRYVELIN
GHRYVELIN (macimorelin) is a diagnostic agent used to test whether the body can produce sufficient growth hormone. It is given as a single-dose oral suspension to adults suspected of having growth hormone deficiency (GHD). GHRYVELIN is not a treatment for growth hormone deficiency; it is solely a diagnostic test that helps doctors confirm or rule out the condition. The test involves drinking a prepared suspension and having blood samples taken over 90 minutes.
The GHRYVELIN test must be performed under medical supervision in a clinical setting. After fasting for at least 8 hours, the healthcare professional prepares the suspension by dissolving the granules in water. You then drink the prepared dose (0.5 mg/kg body weight) within 30 seconds. Venous blood samples are drawn at 45, 60, and 90 minutes after ingestion to measure growth hormone levels. The samples are sent to a laboratory for analysis, and the results help your doctor determine whether you have growth hormone deficiency.
The most common side effects include a bitter or metallic taste in the mouth (dysgeusia), tiredness, headache, nausea, dizziness, diarrhoea, and a sensation of warmth. These effects are generally mild, short-lived, and resolve quickly without treatment, usually within a few hours of taking the test dose. Less common side effects include abdominal pain, feeling cold, hunger, palpitations, drowsiness, and tremor.
Yes, GHRYVELIN can cause temporary changes on an ECG (electrocardiogram), including QT prolongation, which is associated with an increased risk of irregular heartbeat. These changes are transient and short-lived. Patients with known heart disease, cardiac rhythm disorders, or congenital/acquired long QT syndrome should inform their doctor before the test. If you are taking medications that can alter heart rhythm, disclose this to your healthcare provider as the combination may increase the risk.
Yes, preparation is essential for reliable test results. You must fast for at least 8 hours before the test and during the test itself. Avoid strenuous physical exercise for 24 hours before the test. You may drink up to 100 ml of still (non-carbonated) water within 1 hour before and 1 hour after taking the suspension. If you are on growth hormone therapy or medications that affect pituitary hormone secretion, these must be stopped at least 1 month before the test. Any untreated hormonal deficiencies should be addressed before the test as they can affect accuracy.
GHRYVELIN is not recommended during pregnancy. Women of childbearing potential must use effective contraception to ensure they are not pregnant at the time of the test. If you are breastfeeding, a risk to the nursing infant cannot be excluded. Consult your doctor about whether to discontinue breastfeeding or postpone the macimorelin test. The decision should be based on the importance of the diagnostic procedure for your individual health situation.
References and Medical Sources
- European Medicines Agency (EMA). GHRYVELIN (macimorelin) — Summary of Product Characteristics (SmPC). EMA/CHMP, 2019. Available at: ema.europa.eu
- Garcia JM, Biller BMK, Korbonits M, et al. Macimorelin as a diagnostic test for adult GH deficiency. Journal of Clinical Endocrinology & Metabolism. 2018;103(8):3083–3093. doi:10.1210/jc.2018-00665
- Yuen KCJ, Biller BMK, Radovick S, et al. American Association of Clinical Endocrinologists and American College of Endocrinology guidelines for management of growth hormone deficiency in adults and patients transitioning from pediatric to adult care. Endocrine Practice. 2019;25(11):1191–1232. doi:10.4158/GL-2019-0405
- Fleseriu M, Hashim IA, Gurnell M, et al. Hormonal replacement in hypopituitarism in adults: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2016;101(11):3888–3921. doi:10.1210/jc.2016-2118
- Molitch ME, Clemmons DR, Malozowski S, Merriam GR, Vance ML. Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2011;96(6):1587–1609. doi:10.1210/jc.2011-0179
- World Health Organization (WHO). WHO Model List of Essential Medicines. 23rd edition, 2023. Available at: who.int
- Garcia JM, Swerdloff R, Wang C, et al. Macimorelin (AEZS-130)–stimulated growth hormone (GH) test: validation of a novel oral stimulation test for the diagnosis of adult GH deficiency. Journal of Clinical Endocrinology & Metabolism. 2013;98(6):2422–2429. doi:10.1210/jc.2013-1157
- National Institute for Health and Care Excellence (NICE). Human growth hormone (somatropin) in adults with growth hormone deficiency. Technology appraisal guidance TA64, 2003 (updated 2016). Available at: nice.org.uk
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