Hexarelin

What is Hexarelin?

Hexarelin—also known by the international nonproprietary name examorelin—is a synthetic six-amino-acid growth hormone secretagogue (`His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2`). It activates GHS-R1a (ghrelin receptor family), producing prompt, pulsatile endogenous GH release—distinct from injecting recombinant GH.

Research also describes cardiovascular actions that may involve GHS-R1a and CD36-related pathways. Those findings do not establish Hexarelin as a treatment for cardiovascular disease.

Regulatory and sporting status

Hexarelin has no FDA-approved indication, formulation, or dosing schedule. Online “research chemicals” are not equivalent to an FDA-approved medicine. Growth hormone secretagogues are prohibited in sport under WADA; athletes should treat Hexarelin/examorelin as prohibited regardless of marketing as a supplement or research material.

There is currently no FDA-approved dosage for Hexarelin. Study exposures below are not prescribing recommendations.

Human study dosage landscape

Route, units, population, duration, and purpose matter: 2 mcg/kg IV in a monitored challenge cannot be treated as equivalent to a fixed 200 mcg SC dose used repeatedly.

The best-defined acute dose-response

The most useful dose-ranging experiment tested IV boluses of 0.5, 1, and 2 mcg/kg in 12 healthy men. Modeled half-maximal response was about 0.50 mcg/kg by peak and 0.64 mcg/kg by GH AUC; 2 mcg/kg was near the modeled maximum.

This establishes a saturable acute GH effect. It does not prove a fixed 100 mcg dose is universally “saturating.” GH peaked at roughly 30 minutes. Investigators described GH decline with a half-time near 55 minutes—better called the observed decline of the hormone response than Hexarelin plasma half-life.

Route matters: IV, subcutaneous, intranasal, and oral

A human route comparison reported approximate pharmacodynamic “biological bioavailability” of 77% subcutaneous, 4.8% intranasal, and 0.3% oral relative to IV GH response—not a complete modern plasma PK analysis. Oral and intranasal findings should not be converted mechanically into subcutaneous amounts.

What repeated dosing showed

1. Rapid attenuation within two hours. Two 1 mcg/kg IV challenges 120 minutes apart: second GH response significantly smaller.
2. Third daily administration did not raise 24-h GH. 1.5 mcg/kg SC ×2 vs ×3 over 24 hours—both increased integrated GH similarly; three did not beat two.
3. Sixteen weeks: partial, reversible desensitization. 1.5 mcg/kg SC BID in 12 older adults—GH AUC after challenge fell across weeks; recovered near baseline after four weeks off. IGF-1, body fat, lean mass, and BMD did not significantly improve.

Evidence supports partial and reversible attenuation—not stronger online claims that Hexarelin always “stops working” at a specific week or that a particular off-cycle is biologically mandatory.

Dose-by-body-weight examples from human studies

These calculations translate published mcg/kg study doses into total amounts. They are mathematical examples—not recommendations. Fixed online 100–200 mcg amounts superficially resemble some exposures but ignore route, population, frequency, and duration.

Published-study math only — not a dose calculator and not a recommended regimen. No FDA-approved dosage exists.

Research dosage: commonly reported online protocols

The broad online range is approximately 50–300 mcg per administration, with 100–200 mcg the most frequently repeated band. No controlled human trial validates a universal fixed dose, bedtime superiority, fasting requirement, popular cycle lengths, or body-composition outcomes from these protocols.

For a 70 kg adult, 1.5 mcg/kg equals 105 mcg and 3 mcg/kg equals 210 mcg—so numerical resemblance to research may partly explain the convention. That is an inference, not proof that community protocols were derived from those trials.

Clinical evidence versus anecdotal practice

Protocol variations

1. Once vs multiple daily. No optimal frequency established. Third daily administration lacked 24-h GH advantage in one small study; closely spaced IV challenges showed rapid attenuation.
2. Bedtime or fasted timing. Not established as superior clinical timings in Hexarelin trials.
3. Combination with GHRH analogues. Diagnostic synergy (e.g., 0.25 mcg/kg Hexarelin + 1 mcg/kg GHRH IV) does not validate lifestyle stacks with CJC-1295 for body composition.
4. Cycling. Supported: attenuation and recovery after 4 weeks off in one small study. Not supported: mandatory stop at week 4/6/8/12, or that 4 weeks off is optimally sufficient.

Preclinical research doses

Animal and cell experiments clarify mechanisms but should never be converted directly into human doses by simple body-weight arithmetic. Examples include 500 mcg/kg/day SC in aged beagles, 160 mcg/kg IP BID in a rat cachexia model, and rapid in-vitro GHS-R desensitization—none define a human schedule.

Why the studied doses were chosen

1. Acute dose-ranging: IV 0.5, 1, 2 mcg/kg defined response curve and approximate plateau.
2. Route exploration: Larger SC/IN/oral doses compensated for reduced PD availability.
3. Repeated administration: 1.5 mcg/kg SC carried into 24-h and 16-week studies.
4. Diagnostic testing: Lower doses ± GHRH to probe pituitary reserve.
5. Mechanistic cardiac studies: Single 2 mcg/kg IV under intensive monitoring.

No published program established an optimal risk-benefit dose for muscle gain, fat loss, recovery, sleep, or longevity.

Evidence ladder

Dose escalation: what was actually studied

Hexarelin has a formal rising-dose experiment, not a validated week-by-week titration protocol. Participants received separate IV challenges of 0.5, 1, and 2 mcg/kg with washouts under supervision. Little additional peak GH occurred between 1 and 2 mcg/kg. This should not be rewritten as “start low and increase until side effects.”

Safety and tolerability

Small monitored cohorts described acute doses as well tolerated, with slight short-term rises in prolactin, cortisol, and ACTH. The 16-week study did not show chronic ACTH/prolactin overstimulation. These statements should not be expanded into “proven safe.” Long-term cardiovascular, metabolic, pituitary, and cancer-related safety is not established; unapproved product quality is unknown.

Sourcing and origin checks

• Does the source cite a primary human paper, or another vendor page?
• Is the amount weight-based or fixed? Is the route preserved accurately?
• Was the study acute or repeated—and in which population?
• Does “half-life” mean peptide concentration or GH-response decline?
• Is a cycling claim tested, or inferred from desensitization?

Bottom line

Hexarelin has a real but narrow human evidence base: saturable acute GH release, attenuation with repeated dosing, no 24-h GH advantage from a third daily dose in one small study, and no significant IGF-1 or body-composition improvement after 16 weeks BID in older adults.

Fixed 100–200 mcg online protocols remain anecdotal. Report them separately from clinical research—do not treat numerical overlap as clinical validation.

Frequently asked questions

Primary references

• Imbimbo BP et al.

  Growth hormone-releasing activity of Hexarelin in humans: dose-response study

  European Journal of Clinical Pharmacology, 1994.

• Ghigo E et al.

  Growth hormone-releasing activity of Hexarelin by different routes of administration

  1994.

• Rahim A et al.

  Effects of 16 weeks of Hexarelin therapy in healthy elderly subjects

  1998.

• Rahim A et al.

  Pituitary-adrenal and prolactin responses during chronic Hexarelin administration

  1999.

• Maccario M et al.

  Effects of two versus three subcutaneous Hexarelin administrations on 24-hour GH secretion

  2002.

• Sartorio A et al.

  GH response to repeated Hexarelin administration in normal adults

  1996.

• Laron Z et al.

  Long-term intranasal Hexarelin in short children

  1995 — uncontrolled pediatric series.

• WADA

  2026 Prohibited List

  Growth hormone secretagogues prohibited at all times.