Macimorelin
Also known as: Macrilen, GHRP-2 analog
Macimorelin is a synthetic ghrelin receptor agonist primarily used as a diagnostic tool to assess growth hormone deficiency in adults. This orally active peptide stimulates growth hormone release through the ghrelin pathway, making it valuable for clinical evaluation of pituitary function.
Macimorelin is a 509.04 g/mol research peptide. Macimorelin is a synthetic ghrelin receptor agonist primarily used as a diagnostic tool to assess growth hormone deficiency in adults. This orally active peptide stimulates growth hormone release through the ghrelin pathway, making it valuable for clinical evaluation of pituitary function.
Also called: Macrilen, GHRP-2 analog
509.04 g/mol
Molecular Weight
Daltons
1
Strong Evidence
benefits
4
Studies Cited
peer-reviewed
0.5-1
Typical Dose
mg/kg
Overview
Macimorelin represents a breakthrough in growth hormone diagnostics as the first FDA-approved oral growth hormone secretagogue for clinical testing. Unlike traditional growth hormone stimulation tests that require injection, macimorelin offers a convenient oral administration route while maintaining diagnostic accuracy. The peptide works by binding to ghrelin receptors in the pituitary gland, triggering a robust release of endogenous growth hormone that can be measured to assess pituitary function. Beyond its diagnostic applications, researchers investigate macimorelin for its potential therapeutic effects on muscle mass, bone density, and metabolic function. The compound's unique mechanism through the ghrelin pathway provides insights into appetite regulation, energy metabolism, and growth hormone physiology.
Key Takeaways: Macimorelin
- Strongest evidence supports Macimorelin for growth hormone deficiency diagnosis
- Research doses typically range from 0.5 to 1 mg/kg via oral
- 1 benefits with strong evidence, 3 moderate, 2 preliminary
- Half-life: 4-6 hours
- 4 cited research studies in this guide
Mechanism of Action
Macimorelin functions as a selective agonist of the growth hormone secretagogue receptor (GHSR-1a), also known as the ghrelin receptor. Upon binding to these receptors located in the anterior pituitary and hypothalamus, macimorelin activates intracellular signaling cascades involving protein kinase C and calcium mobilization. This activation stimulates somatotroph cells to release growth hormone in a pulsatile manner similar to endogenous ghrelin. The compound also influences appetite regulation and metabolic processes through its action on hypothalamic centers controlling energy balance.
Research Benefits
Macimorelin at a Glance
Macimorelin functions as a selective agonist of the growth hormone secretagogue receptor (GHSR-1a), also known as the ghrelin receptor.
Growth Hormone Deficiency Diagnosis
Strong EvidenceProvides accurate diagnostic assessment of adult growth hormone deficiency through oral administration, eliminating the need for injectable stimulation tests while maintaining clinical reliability.
Muscle Mass Preservation
Moderate EvidenceStimulates growth hormone release that promotes protein synthesis and muscle tissue maintenance, particularly beneficial for age-related muscle loss research.
Bone Density Support
Moderate EvidenceGrowth hormone stimulation contributes to bone formation and mineral density through enhanced IGF-1 production and osteoblast activity.
Appetite Regulation
Moderate EvidenceActivates ghrelin pathways involved in hunger signaling and energy balance, providing research insights into eating behavior and metabolic control.
Metabolic Function Enhancement
PreliminaryInfluences glucose metabolism and lipid utilization through growth hormone-mediated pathways, potentially improving insulin sensitivity and fat oxidation.
Sleep Quality Improvement
PreliminaryGrowth hormone release enhancement may improve sleep architecture and recovery processes through its natural circadian rhythm effects.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Growth hormone stimulation test | 0.5–1 mg/kg | oral |
| Metabolic research | 0.2–0.5 mg/kg | oral |
Frequency
Single dose for diagnostic purposes, or as per research protocol
Timing
Fasting state required, typically morning administration
Cycle Length
Single administration for diagnostics, variable for research studies
Research Notes
- 1Must be administered in fasting state (at least 6 hours)
- 2Growth hormone levels measured at specific time intervals post-administration
- 3Avoid food intake for 1 hour after administration
- 4Individual dosing based on body weight calculation
Reconstitution Guide
Standard Reconstitution
Vial Size
60 mg
Bacteriostatic Water
120 mL
Concentration
5 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
Macimorelin vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 120 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at 2-8°C (oral solution). 24 months unopened, use within 2 hours once mixed.
Storage Temperature
2-8°C (oral solution)
Shelf Life
24 months unopened, use within 2 hours once mixed
Important Notes
- •Available as oral powder for solution preparation
- •Must be prepared fresh before each administration
- •Clear solution should be obtained after mixing
- •Do not use if particles or discoloration are present
Macimorelin Dosing Calculator
Calculate daily intake, cycle totals, and vials needed with pre-filled protocols →
Macimorelin Reconstitution Calculator
Calculate concentration, syringe units, and doses per vial with auto-filled values →
Safety & Side Effects
Reported Side Effects
- !Nausea and vomiting
- !Increased appetite
- !Abdominal discomfort
- !Dizziness
- !Headache
- !Fatigue
- !Altered taste perception
- !Injection site reactions (if applicable)
- !Hypoglycemia risk
- !Sleep disturbances
Potential Interactions
- ⚡Insulin and antidiabetic medications (monitor glucose levels)
- ⚡Corticosteroids (may blunt growth hormone response)
- ⚡Thyroid hormones (potential interaction with GH axis)
- ⚡Opioid medications (may affect growth hormone release)
- ⚡Alcohol (avoid during testing periods)
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
Macimorelin as a Diagnostic Test for Adult GH Deficiency
Phase 3 clinical trial demonstrating macimorelin's efficacy as an oral diagnostic test for adult growth hormone deficiency with sensitivity and specificity comparable to insulin tolerance test.
Pharmacokinetics and Safety of Oral Macimorelin
Comprehensive pharmacokinetic study establishing optimal dosing protocols and safety profile for macimorelin in healthy subjects and patients with suspected GH deficiency.
Ghrelin Receptor Agonism and Metabolic Effects
Research examining macimorelin's effects on glucose metabolism, insulin sensitivity, and lipid profiles through ghrelin receptor activation in metabolic research models.
Macimorelin vs Traditional GH Stimulation Tests
Comparative analysis of diagnostic accuracy between macimorelin and conventional growth hormone stimulation tests, highlighting advantages of oral administration.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
Macimorelin offers the advantage of oral administration compared to injectable tests like insulin tolerance test or arginine stimulation. It provides similar diagnostic accuracy while being more convenient and better tolerated by patients.
Research dosages typically range from 0.2-1.0 mg/kg body weight administered orally, depending on the specific research application. Diagnostic protocols usually use 0.5-1.0 mg/kg as a single dose.
Macimorelin typically stimulates growth hormone release within 30-60 minutes of oral administration, with peak levels occurring around 60-90 minutes post-dose.
While macimorelin stimulates growth hormone release, its primary approved use is for diagnostic purposes. Research into muscle-building applications is ongoing but not yet established for therapeutic use.
Common side effects include nausea, increased appetite, abdominal discomfort, dizziness, and headache. Most side effects are mild and resolve within a few hours of administration.
Macimorelin has advantages in oral bioavailability and regulatory approval for diagnostic use, while GHRP compounds typically require injection. The choice depends on specific research objectives and administration preferences.
Macimorelin powder should be stored at 2-8°C in a refrigerator. Once prepared as an oral solution, it must be used within 2 hours and cannot be stored for later use.
Yes, macimorelin can potentially cause hypoglycemia, particularly in susceptible individuals. Blood glucose monitoring may be warranted during research protocols, especially in diabetic subjects.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.