CGRP vs Splenin

Binds CLR/RAMP1 receptor complex. Causes vasodilation via cAMP/PKA/nitric oxide pathway. Modulates nociceptive signaling in the trigeminal system. Promotes bone healing and has anti-inflammatory effects in peripheral tissues.

CGRP (calcitonin gene-related peptide) is a 37-amino-acid endogenous neuropeptide produced by alternative splicing of the calcitonin gene, expressed predominantly in sensory neurons of the trigeminal system and peripheral vasculature, where it functions as a potent vasodilator and pain neuromodulator central to migraine pathophysiology. CGRP activates its receptor complex (CLR/RAMP1) to mediate vasodilation and nociceptive signal amplification; during migraine attacks, trigeminal activation releases CGRP at elevated plasma concentrations, and blockade of this pathway has been established as the primary validated pharmacological target for modern preventive migraine therapy. Phase 3 randomized controlled trials published in the New England Journal of Medicine and the Lancet — including the STRIVE trial (Goadsby et al. 2017) and a Phase 3b study in treatment-refractory patients — demonstrated that anti-CGRP monoclonal antibodies significantly reduced monthly migraine days versus placebo, validating the pathway and supporting FDA approval of erenumab, fremanezumab, and galcanezumab. CGRP itself is an endogenous neuropeptide and is not a therapeutic agent that is compounded or administered by providers; the FDA-approved interventions are monoclonal antibody and small-molecule receptor antagonists available by prescription, and exogenous CGRP peptide is exclusively a research tool compound used in vasodilatory and pain signaling pharmacology studies.

Spleen-derived tetrapeptide bioregulator; normalizes leukocyte and platelet production; modulates splenic immune cell activity

Splenin is a synthetic tripeptide (Lys-Glu-Asp, KED) classified as a Khavinson-class bioregulator peptide targeted at splenic and immune tissue, investigated for immunomodulatory and cytoprotective properties through proposed gene expression regulatory mechanisms in lymphoid and hematopoietic cell populations. Like other short Khavinson bioregulator peptides, splenin is proposed to modulate gene expression in target immune cells via epigenetic mechanisms, with published research on the class demonstrating that ultrashort peptides can influence differentiation of stem and progenitor cells and regulate gene activity in aging tissues. Research on Khavinson-class ultrashort peptides has characterized neuroepigenetic mechanisms of action in neurodegeneration models and demonstrated peptide regulation of cell differentiation in stem cell preparations, providing the class-level mechanistic context within which splenin is proposed to act on immune tissue. Splenin has no FDA approval or regulatory approval in any major jurisdiction outside Russia; evidence derives from Khavinson-series preclinical and class-level studies with no independent clinical trials published in Western-indexed journals.