GHRP-4

GHRP-4 is a synthetic tetrapeptide with the primary sequence D-Trp–L-Ala–L-Trp–D-Phe–NH2 (molecular weight 607.7 Da; molecular formula C34H37N7O4). It belongs to the growth hormone-releasing peptide (GHRP) family, a series of met-enkephalin analogs incorporating unnatural D-amino acid substitutions that confer resistance to enzymatic degradation and eliminate opioid receptor activity while preserving GH-releasing potency.

At the molecular level, GHRP-4 is understood by structural analogy to the class to act as an agonist at the growth hormone secretagogue receptor type 1a (GHS-R1a), a Gq-coupled G protein-coupled receptor whose endogenous ligand is ghrelin. Binding activates the phospholipase C / inositol trisphosphate / intracellular calcium cascade in anterior pituitary somatotrophs, triggering growth hormone secretion. Protein kinase C has been implicated in GHRP-stimulated GH secretion across the class. Preclinical research with better-characterized analogs also supports a second, hypothalamic site of action involving suppression of somatostatin tone and upregulation of GHRH mRNA in the arcuate nucleus.

GHRP-4 shares no structural homology with GHRH and acts through a receptor entirely distinct from the GHRH receptor. It emerged from iterative medicinal chemistry work at Tulane University (Bowers laboratory) in the 1980s as part of the developmental series that produced GHRP-1, GHRP-6, and ultimately GHRP-2. No receptor binding affinity (Ki) or functional potency (EC50) data specific to GHRP-4 have been published in the peer-reviewed literature.

GHRP-4 has not been the subject of any published clinical trials, human pharmacokinetic studies, or formal preclinical pharmacology studies as of mid-2025. It represents an early intermediate in the developmental series from the Bowers laboratory that was largely superseded by GHRP-2 (pralmorelin) and GHRP-6, which became the reference compounds for the class.

The only peer-reviewed paper to characterize GHRP-4 as a named compound is a 2025 biophysical study (PMC12869127) examining the secondary structure, thermal stability, and model membrane interactions of eight GHRPs. That investigation found that GHRP-4 exhibits pronounced temperature-dependent structural changes by electronic circular dichroism spectroscopy, distinct from the more thermally stable GHRP-1. Notably, GHRP-4 could not be analyzed in sodium dodecyl sulfate micelle systems due to immediate particle aggregation, a biophysical property not observed with all class members.

Pharmacological and clinical evidence for the GH-secretagogue effect exists only for related class members. A 2017 systematic review (PMC5392015, Berlanga-Acosta et al.) documented preclinical and early human evidence for GHRP-2, GHRP-6, and hexarelin, including cardioprotective, anti-inflammatory, and anabolic activities mediated through GHS-R1a and CD36 pathways. A separate review of GHS safety and efficacy (PMC5632578) reported that hexarelin increased linear growth velocity from 5.3 plus or minus 0.8 to 8.3 plus or minus 1.7 cm/year in short-statured children, and that GHRP-2 increased food intake by approximately 36% versus placebo in wasting studies. These findings cannot be assumed to apply to GHRP-4, whose pharmacology has not been independently evaluated. Extrapolation to GHRP-4 remains speculative.

Typical dosage: 100-200 mcg (twice daily).

No dosing protocol for GHRP-4 exists in peer-reviewed literature, regulatory filings, or any clinical study. The compound is available exclusively through research chemical suppliers and is not approved by the FDA or any comparable regulatory body for human administration.

Any dosing that occurs in community or performance contexts is derived by extrapolation from the best-studied class members. Published clinical studies with GHRP-2 and GHRP-6 have used intravenous and subcutaneous doses in the range of 1–2 micrograms per kilogram body weight, with some protocols using fixed doses of approximately 100 micrograms per injection, administered one to three times daily. The general pharmacological principle across the GHRP class is that GH pulse amplitude approaches saturation at approximately 100–200 micrograms per injection, with diminishing incremental return above that range.

Community reports on GHRP-4 are sparse compared to GHRP-2 and GHRP-6. Anecdotal community use, where it exists, mirrors the 100–300 microgram subcutaneous injection range used with other GHRPs, administered in a fasted state and timed around sleep to coincide with natural GH pulsatility. The unique biophysical properties of GHRP-4, including its aggregation behavior documented in the 2025 structural study, mean that direct dose equivalence to other GHRPs is not supported.

This information is provided for educational purposes only and does not constitute medical advice. GHRP-4 is an uninvestigated research compound with no validated human dosing guidance.

No compound-specific stability data has been identified for this peptide. The general lyophilized-peptide handling framework applies — see Storage & handling for temperature, reconstitution diluent, and beyond-use dating principles.

No studies of any design have examined GHRP-4 in combination with other compounds. All of the following reflects speculation extrapolated from research on other GHRP-class members and is entirely anecdotal.

Within the performance peptide community, GHRP-class compounds are routinely paired with GHRH analogs such as CJC-1295 (with or without the drug affinity complex modification) or modified GRF(1-29). The pharmacological rationale — established for GHRP-2 and GHRP-6 in peer-reviewed settings — is that GHRH analogs and GHRPs act on distinct receptor systems (GHRH-R and GHS-R1a respectively), producing supra-additive GH release when co-administered. Whether GHRP-4 participates in the same synergistic interaction is untested. Some community users also report combining GHRP-class peptides with IGF-1 analogs or insulin, combinations that carry meaningful safety risks and for which no evidence base exists.

GHRP-4 is not currently FDA-approved for any indication. It is generally classified as a research compound. Regulatory status varies by country.

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Reported side effects: Well-tolerated

No adverse effect data specific to GHRP-4 have been published. The following is derived from class-level safety literature on GHRP-2, GHRP-6, hexarelin, and ipamorelin, as summarized in a systematic review (PMC5632578, Sigalos and Pastuszak, 2018).

The review concluded that growth hormone secretagogues "appear safe" based on available short-term human data, but explicitly acknowledged insufficient long-term data on cancer incidence and mortality — the same concern that restricts therapeutic exogenous GH use. Most trials included in that review were small and of short duration.

Class-level adverse effects include: • Transient elevation of cortisol and ACTH, particularly with GHRP-6 • Increased appetite and food intake, attributable to GHS-R1a engagement in ghrelin-mediated hunger signaling • Impaired glucose metabolism, including elevated fasting glucose and HbA1c, documented with chronic GHS use • Fluid retention and musculoskeletal discomfort, more pronounced with the non-peptide secretagogue ibutamoren • Elevated prolactin reported in some subjects

The theoretical risk of IGF-1-mediated cancer cell proliferation with any GH-stimulating compound cannot be dismissed, though no oncological signal has been confirmed in published GHRP trials. GHRP-4's aggregation behavior in SDS micellar systems, noted in the 2025 biophysical study, is of uncertain clinical significance but distinguishes it from other class members.

GHRP-4 is not approved for human use. No contraindication, drug interaction, or long-term toxicology data exist for this specific compound.