AICAR vs GHRP-2

Converted intracellularly to ZMP, a potent AMPK activator. AMPK activation increases fatty acid oxidation, glucose uptake, and mitochondrial biogenesis — the same metabolic pathways activated by sustained aerobic exercise.

AICAR (5-aminoimidazole-4-carboxamide ribonucleotide; acadesine) is a non-peptide, cell-permeable nucleoside analog and prodrug that is phosphorylated intracellularly to its monophosphate form (ZMP), which mimics AMP to activate AMP-activated protein kinase (AMPK) — the primary cellular energy sensor — producing metabolic effects that partially phenocopy those of exercise and caloric restriction. AMPK activation by AICAR upregulates GLUT4 expression and glucose uptake, stimulates fatty acid oxidation, increases mitochondrial biogenesis via PGC-1alpha, and suppresses hepatic gluconeogenesis; a landmark 2008 preclinical study demonstrated that AICAR administration in sedentary mice increased running endurance and activated exercise-related gene expression programs without physical training, generating significant research interest in its potential as an exercise mimetic. The only published human clinical trial involved intravenous AICAR administration in patients with type 2 diabetes, where it reduced hepatic glucose output and inhibited whole-body lipolysis via AMPK, validating the pathway pharmacology in humans; the exercise-mimetic effects observed in rodents have not been replicated or evaluated in any human study, and no oral or injectable form has been assessed for human performance use in published research. AICAR is not a peptide and has no FDA approval; it is prohibited in sport by WADA, available only as a research chemical, and all performance-related interest derives from preclinical rodent data that has not been translated to human investigation; the IV metabolic effects in diabetic patients should not be extrapolated to an athletic or performance context.

Synthetic hexapeptide that stimulates pulsatile growth hormone release from the anterior pituitary by acting on the ghrelin receptor (GHSR-1a). Commonly stacked with GHRH analogs such as CJC-1295 or Sermorelin to amplify GH output synergistically.

GHRP-2 (growth hormone-releasing peptide-2; pralmorelin; KP-102) is a synthetic hexapeptide (D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2) and potent ghrelin receptor (GHS-R1a) agonist developed as a GH secretagogue with established efficacy in stimulating pulsatile GH release from pituitary somatotrophs, characterized by potent GH stimulation alongside non-selective co-stimulation of cortisol and prolactin secretion. As a first-generation GHRP, GHRP-2 achieves its GH-secretory effect through direct GHS-R1a agonism with amplification by endogenous GHRH; it is distinguished from later selective GHRPs such as ipamorelin by its non-selective endocrine profile, and synergistic GH stimulation is observed when combined with GHRH analogs in diagnostic protocols. GHRP-2 has been validated as a diagnostic agent for the GHRP-2 stimulation test used in Japan to assess GH secretion capacity in adults with suspected hypopituitarism or post-surgical pituitary dysfunction, with published human clinical data supporting its reliability as a GH stimulation tool in endocrine diagnostic practice. GHRP-2 has no FDA approval for any therapeutic or diagnostic indication in the United States; it is used diagnostically in Japan and as a research compound elsewhere, with no approved indication for GH enhancement, performance, or anti-aging applications, and its non-selective endocrine stimulation profile represents a relevant consideration versus more selective GH secretagogues. GHRP-2 dosage in research contexts: doses of 100–300 mcg per subcutaneous injection are documented across research protocols, typically administered 2–3 times daily. Co-administration with a GHRH analog (such as CJC-1295 or sermorelin) produces synergistic GH release and is studied in combination protocols for this reason. Administration is by subcutaneous injection following reconstitution with bacteriostatic water. GHRP-2 vs GHRP-6 vs ipamorelin: GHRP-2 produces potent GH release but with co-stimulation of cortisol and prolactin, similar to GHRP-6. The key distinguishing feature of GHRP-6 is stronger appetite stimulation (ghrelin-like effect); GHRP-2 produces less appetite stimulation with comparable or slightly greater GH output per dose. Both are non-selective compared to ipamorelin, which was developed specifically to achieve GH stimulation without the cortisol and prolactin co-elevation that characterizes first-generation GHRPs. For research contexts prioritizing GH selectivity, ipamorelin is generally preferred; GHRP-2 is used where its diagnostic validation and potent GH stimulation profile are the research objectives.