MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
Ghrelin Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
Ghrelin (lenomorelin, acyl-ghrelin) is the stomach-derived 28-amino-acid "hunger hormone" and the endogenous agonist of the GHS-R1a receptor. An octanoyl group on serine-3, added by the enzyme GOAT, is required for activity (PMID 10604470). Activating GHS-R1a drives pulsatile growth-hormone release and potently stimulates appetite, while also raising ACTH, cortisol, prolactin, and blood glucose and improving gut and cardiac function (PMC3644599). In human research it is dosed intravenously, most commonly a ~1 mcg/kg bolus or a low-rate infusion; repeat-dose heart-failure and cachexia studies used 2 mcg/kg twice daily for three weeks (PMID 15569841). The subcutaneous reconstitution figures on this page are an educational measurement reference only, since trials use the IV route. Ghrelin is not FDA- or EMA-approved and is presented for educational purposes, not medical advice.
Reconstitute: Add 2 mL bacteriostatic water → 2.5 mg/mL concentration.
Typical dose: ~25-150 mcg per dose (≈0.3-2 mcg/kg); IV in studies; research only
Easy measuring: At 2.5 mg/mL, 1 unit = 0.01 mL = 0.0250 mg (25 mcg) on a U-100 insulin syringe.
Storage: Lyophilized powder stored frozen at −20 °C and protected from light and moisture; reconstituted solution kept refrigerated at 2-8 °C. Because acyl-ghrelin is prone to deacylation (loss of the octanoyl group converts it to inactive des-acyl ghrelin), reconstituted material is best used within roughly 1-2 weeks and discarded by ~4 weeks; avoid repeated freeze-thaw cycles.
Half-life: Short, roughly 10-30 minutes; the octanoyl ester is rapidly cleaved to inactive des-acyl ghrelin, so effects are brief.
Route: Intravenous in all published human studies (bolus or infusion); not orally active. Subcutaneous figures here are an educational model only.
Status: Not FDA- or EMA-approved; research/diagnostic use only. Educational content, not medical advice.
About Ghrelin
Ghrelin, the body's principal "hunger hormone," is a 28-amino-acid peptide that acts as the endogenous agonist of the growth hormone secretagogue receptor (GHS-R1a). Its defining feature is an octanoyl group on serine-3 (hence "acyl-ghrelin"), installed by the enzyme GOAT, which is essential for activating the receptor and releasing growth hormone [1][8]. Clinically, and in every published human trial, ghrelin is delivered INTRAVENOUSLY, either as a single bolus near 1 mcg/kg or as a timed infusion; the subcutaneous reconstitution figures below are an educational measurement reference only, not the real-world route [2][4].\n\nThis guide models a 5 mg vial reconstituted with 2 mL of bacteriostatic water (2.5 mg/mL) so doses map cleanly onto a U-100 insulin syringe: 25 mcg ≈ 1 unit, 75 mcg ≈ 3 units (about 1 mcg/kg for a 75 kg adult), 100 mcg ≈ 4 units, and 150 mcg ≈ 6 units (about 2 mcg/kg). Research bolus doses cluster near 1 mcg/kg, while repeated heart-failure and cachexia protocols used 2 mcg/kg twice daily for up to three weeks [2][5].\n\nFrequency: In repeat-dose human studies ghrelin was given twice daily; acute appetite and growth-hormone experiments typically used a single timed bolus or a 30-300 minute infusion. Ghrelin (lenomorelin) is not FDA- or EMA-approved and is presented here for educational purposes only, not as medical advice.
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 2 mL of bacteriostatic water into a sterile syringe.
Inject the water slowly down the inner wall of the 5 mg ghrelin vial; do not aim the stream directly at the powder, and do not shake.
Gently swirl or roll the vial until the solution is completely clear; the result is a 2.5 mg/mL concentration (25 mcg per insulin-syringe unit).
Store refrigerated at 2-8 °C and draw the prescribed number of units per dose (25 mcg ≈ 1 unit, 75 mcg ≈ 3 units, 100 mcg ≈ 4 units, 150 mcg ≈ 6 units).
Educational note: ghrelin is administered INTRAVENOUSLY in human studies (bolus or infusion) — these subcutaneous reconstitution figures are a measurement reference only; because acyl-ghrelin deacylates over time, prepare small amounts and use within roughly 1-2 weeks.
Interactive Ghrelin Syringe Calculator
Currently visualizing the 5 mg vial reconstituted with 2 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 5mg dry powder in 2mL water yields 2.50 mg/mL. To evaluate a 250mcg dose, pull to 10.0 units (10 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Low test / GH-axis probe (~0.3 mcg/kg) | 25 mcg | 1 units (0.01 mL) |
| Standard research bolus (~1 mcg/kg) | 75 mcg | 3 units (0.03 mL) |
| Appetite / GH study (~1.5 mcg/kg) | 100 mcg | 4 units (0.04 mL) |
| Cachexia-style repeat dose (~2 mcg/kg) | 150 mcg | 6 units (0.06 mL) |
Administration guidelines: Refer to guidelines | 2 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 5 mg vial.
Peptide Vials (Ghrelin, 5 mg each):
- check8-week course: ~3-4 vials at twice-daily research-style dosing (allowing for discard within the stability window)
- check12-week course: ~4-5 vials
- check16-week course: ~6 vials
- checkBecause acyl-ghrelin deacylates over time, reconstitute small amounts and discard unused solution after ~1-2 weeks rather than stockpiling
Insulin Syringes (U-100):
- check8-week course: ~120 syringes (one 100-count box plus spares) at 14 injections/week
- check12-week course: ~180 syringes
- check16-week course: ~230 syringes
- checkUse a fresh sterile syringe for every injection and for each vial draw
Bacteriostatic Water (30 mL bottles): Use 2 mL per vial for reconstitution.
- check8-week course: one 30 mL bottle comfortably covers reconstitution of ~3-4 vials
- check12-week course: one 30 mL bottle
- check16-week course: one to two 30 mL bottles
- checkEach 5 mg vial uses 2 mL, yielding 2.5 mg/mL (25 mcg per insulin-syringe unit)
Alcohol Swabs:
- check8-week course: ~250 swabs (vial septum plus injection site each time)
- check12-week course: ~350 swabs
- check16-week course: ~500 swabs
- checkSwab the vial stopper and the skin site before every injection
Mechanism of Action (MOA)
Ghrelin is a 28-amino-acid peptide first purified from rat and human stomach by Kojima and colleagues in 1999 as the long-sought endogenous ligand for the orphan growth hormone secretagogue receptor [1]. Its hallmark is a post-translational modification: the hydroxyl of serine-3 carries an n-octanoyl (C8) fatty-acid chain attached by ghrelin O-acyltransferase (GOAT), a membrane-bound O-acyltransferase. This acylation is obligatory for high-affinity binding to and activation of the growth hormone secretagogue receptor type 1a (GHS-R1a); the non-acylated form (des-acyl ghrelin) circulates in larger amounts but does not activate GHS-R1a in the classical way [1][8]. Ghrelin is produced predominantly by gastric X/A-like (oxyntic) cells, with smaller contributions from the intestine, pancreas, and hypothalamus.\n\nGHS-R1a is a Gq/11-coupled receptor expressed in the anterior pituitary, hypothalamic arcuate nucleus, pancreatic islets, adrenal gland, myocardium, and vagal afferents [8]. At the pituitary and hypothalamus, ghrelin amplifies pulsatile growth-hormone secretion, synergizing with GHRH and opposing somatostatin [2][4]. In the arcuate nucleus it activates NPY/AgRP neurons to drive appetite, meal initiation, and food intake, making it the only peripheral hormone known to directly increase hunger [3]. Downstream, ghrelin administration reliably raises circulating ACTH, cortisol, and prolactin, accelerates gastric emptying and gut motility, and produces a consistent rise in blood glucose with relatively unchanged or reduced insulin, which is why continuous infusion can worsen glucose tolerance [2][4]. It also exerts cardiovascular actions, improving left-ventricular function, cardiac output, and exercise capacity while attenuating muscle wasting in heart failure and cachexia models [5][6][7].\n\nPharmacokinetics: ghrelin is given intravenously in human studies as a bolus (most commonly ~1 mcg/kg, range ~0.03-10 mcg/kg) or as an infusion (commonly ~0.017 mcg/kg/min, range 0.003-1.33 mcg/kg/min over 30-300 minutes) [2]. Plasma clearance is rapid: reported elimination half-life is short, on the order of ~10-30 minutes, because the labile octanoyl ester is cleaved by plasma and tissue esterases, converting active acyl-ghrelin to des-acyl ghrelin [2][8]. Oral bioavailability is negligible (the peptide is degraded in the gut), so the molecule is not orally active; the short half-life is why repeat-dose protocols used twice-daily administration [5].\n\nThe real-world route is intravenous; the subcutaneous reconstitution scheme on this page is the educational measurement convention used across this site, not a clinically validated delivery method. Ghrelin (lenomorelin) is not approved by any major regulator and is restricted to research and diagnostic use [2].
Clinical Trial Efficacy Highlights
- starKojima and colleagues (1999, Nature) purified ghrelin from stomach and showed it is a 28-amino-acid peptide whose serine-3 n-octanoylation is essential for activating GHS-R1a; the acylated peptide released growth hormone both in vitro and in vivo, establishing ghrelin as the endogenous growth-hormone secretagogue and the founding evidence for its mechanism [1].
- starWren and colleagues (2001, J Clin Endocrinol Metab) infused intravenous ghrelin at 5.0 pmol/kg/min in a randomized, double-blind, placebo-controlled crossover study and found a clear-cut increase in food intake, with energy consumed from a free-choice buffet rising by a mean of about 28% versus saline, providing the first direct human evidence that ghrelin is a potent orexigen [3].
- starGarin and colleagues (2013, J Clin Endocrinol Metab) systematically reviewed the human experience with ghrelin administration across more than 100 studies and confirmed dose-dependent stimulation of growth hormone, ACTH, cortisol, prolactin, glucose, and appetite, with bolus doses most commonly 1 mcg/kg and infusion rates most commonly ~0.017 mcg/kg/min [2].
- starBroglio and colleagues (2008, J Endocrinol Invest) gave a continuous overnight infusion of acylated ghrelin (0.5 mcg/kg/h over 16 hours) and showed enhanced growth-hormone secretion alongside deteriorated glucose metabolism (higher post-meal glucose responses) and suppressed lipolysis, demonstrating the metabolic trade-offs of sustained GHS-R1a activation [4].
- starNagaya and colleagues (2004, Circulation) administered synthetic ghrelin 2 mcg/kg intravenously twice daily for three weeks to patients with chronic heart failure and reported improved left-ventricular function, increased exercise capacity, and attenuated muscle wasting, supporting a therapeutic signal in cardiac cachexia [5].
- starNagaya and colleagues (2001, Circulation) showed in a rat heart-failure model that chronic subcutaneous ghrelin (100 mcg/kg twice daily for three weeks) improved left-ventricular dysfunction, limited remodeling, and attenuated the development of cardiac cachexia with greater body-weight gain than placebo, providing preclinical support for the later human trials [6].
- starHage and colleagues (2023, European Journal of Heart Failure) confirmed in patients with heart failure and reduced ejection fraction that acute acyl-ghrelin infusion increased circulating growth hormone, reinforcing that exogenous ghrelin engages the GH axis even in this population [7].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningTransient facial flushing is the most common acute effect, reported in roughly 10% of volunteers during or shortly after intravenous administration [2].
- warningGastrointestinal effects such as audible gastric rumbling (borborygmi), increased hunger, and accelerated gastric motility occur in a minority of subjects, consistent with ghrelin's prokinetic and orexigenic actions [2][3].
- warningA consistent rise in blood glucose with unchanged or reduced insulin can occur; continuous or repeated infusion can worsen glucose tolerance, a particular concern for people with prediabetes, diabetes, or metabolic syndrome [4].
- warningGhrelin reliably increases circulating ACTH, cortisol, and prolactin, so it transiently activates the HPA axis; this is expected pharmacology rather than a defect but is relevant in endocrine-sensitive individuals [2].
- warningIncreased appetite and food intake are intrinsic effects and may be undesirable outside a cachexia/anorexia context; the orexigenic action is potent (comparable to NPY in human studies) [3].
- warningLess common reports include thirst, mild sweating, somnolence, and transient blood-pressure or heart-rate changes; across the human literature about 20% of participants experienced some adverse event, but serious adverse events were extremely rare [2].
- warningThe very short half-life (~10-30 minutes) and rapid deacylation mean effects are brief and sustained action requires infusion or repeated dosing; this also makes reconstituted acyl-ghrelin chemically unstable and prone to losing potency over time [2][8].
- warningRegulatory/research status: ghrelin (lenomorelin) is NOT approved by the FDA or EMA for any indication, is not a dietary supplement, and is intended only for research or diagnostic use; long-term human safety is not established. This page is educational and not medical advice [2].
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical Ghrelin dosage?expand_more
In human research, the typical Ghrelin dosage is an intravenous bolus of about 1 mcg/kg (roughly 70-150 mcg for most adults), with the broader studied range spanning ~0.3 to 2 mcg/kg per administration; continuous infusions commonly run near 0.017 mcg/kg/min over 30-300 minutes. Repeat-dose heart-failure and cachexia protocols used 2 mcg/kg twice daily. These figures are from clinical and educational literature only; ghrelin is not an approved medicine, and nothing here is medical advice.
How do I reconstitute Ghrelin for the measurement model on this page?expand_more
This educational model uses a 5 mg vial and 2 mL of bacteriostatic water, yielding 2.5 mg/mL (25 mcg per unit on a U-100 insulin syringe). Draw 2 mL of bacteriostatic water, inject it slowly down the vial wall, and swirl gently until clear. At this concentration, 25 mcg ≈ 1 unit, 75 mcg ≈ 3 units, and 150 mcg ≈ 6 units. Note that human studies actually use the intravenous route; the subcutaneous figures are a measurement reference.
What is the half-life of Ghrelin?expand_more
Acyl-ghrelin has a short plasma half-life, on the order of about 10-30 minutes, because the octanoyl group on serine-3 is rapidly cleaved by esterases, converting active ghrelin into inactive des-acyl ghrelin. This rapid clearance is why sustained effects require a continuous infusion or repeated (e.g., twice-daily) dosing, and why reconstituted material loses potency relatively quickly.
Is Ghrelin FDA approved?expand_more
No. Ghrelin (INN lenomorelin) is not approved by the FDA or the EMA for any indication; it is used only as a research and diagnostic peptide. Some related GHS-R1a agonists differ in status (for example, the small-molecule anamorelin is approved in Japan for cancer cachexia, and macimorelin is FDA-approved as a diagnostic for adult growth-hormone deficiency), but ghrelin itself remains unapproved.
How is Ghrelin administered in studies, and can it be stacked?expand_more
In published trials ghrelin is given intravenously, either as a single timed bolus or as an infusion; oral dosing is ineffective because the peptide is degraded in the gut. It has been studied alongside standard care in heart failure and cachexia rather than as a recreational stack, and combining a potent orexigenic, GH-stimulating, glucose-raising hormone with other agents has not been characterized for safety. Because ghrelin is research-only and not a medicine, this is educational information, not a recommendation to use it.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing Ghrelin, plus the universal dosing calculator.
Academic References & Study Citations
Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656-660. View Scientific Paper →
Garin MC, Burns CM, Kaul S, Cappola AR. The human experience with ghrelin administration. J Clin Endocrinol Metab. 2013;98(5):1826-1837. View Scientific Paper →
Wren AM, Seal LJ, Cohen MA, et al. Ghrelin enhances appetite and increases food intake in humans. J Clin Endocrinol Metab. 2001;86(12):5992-5995. View Scientific Paper →
Broglio F, Prodam F, Riganti F, et al. The continuous infusion of acylated ghrelin enhances growth hormone secretion and worsens glucose metabolism in humans. J Endocrinol Invest. 2008. View Scientific Paper →
Nagaya N, Moriya J, Yasumura Y, et al. Effects of ghrelin administration on left ventricular function, exercise capacity, and muscle wasting in patients with chronic heart failure. Circulation. 2004;110(24):3674-3679. View Scientific Paper →
Nagaya N, Uematsu M, Kojima M, et al. Chronic administration of ghrelin improves left ventricular dysfunction and attenuates development of cardiac cachexia in rats with heart failure. Circulation. 2001;104(12):1430-1435. View Scientific Paper →
Hage C, et al. Acyl ghrelin infusion increases circulating growth hormone in patients with heart failure and reduced ejection fraction. Eur J Heart Fail. 2023;25(11):2093-2103. View Scientific Paper →
Müller TD, Nogueiras R, Andermann ML, et al. Ghrelin. Mol Metab. 2015;4(6):437-460. View Scientific Paper →