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Neuropeptide / Immunomodulator

VIP (Vasoactive Intestinal Peptide)

Also known as: Vasoactive Intestinal Peptide, Aviptadil (branded form)

A naturally occurring 28-amino-acid neuropeptide with wide-ranging effects on vasodilation, immune regulation, and smooth muscle — studied in a small human Phase II trial for inhaled delivery in sarcoidosis.

Educational content, not advice. Compiled from information publicly available on the internet; it may contain inaccuracies and was not written or reviewed by medical professionals. Use it as a starting point for your own research, verify against primary sources, and see our full disclaimer.

Overview

VIP is a naturally occurring 28-amino-acid neuropeptide with broad physiological roles: vasodilation, smooth muscle relaxation, anti-inflammatory/immunoregulatory signaling, and modulation of gastric motility and hormone secretion. A synthetic form (aviptadil) has been studied clinically under various brand names, including in trials for pulmonary hypertension and, more recently, COVID-19.

Proposed Mechanism of Action

VIP acts on VPAC1 and VPAC2 receptors, G-protein-coupled receptors expressed across smooth muscle, immune cells, and neural tissue — the wide receptor distribution is the basis for VIP's unusually broad range of studied effects, from blood vessel dilation to cytokine modulation.

Research Context

The cited trial treated 20 patients with active sarcoidosis (a chronic inflammatory disease) with nebulized (inhaled) VIP over 4 weeks in an open-label Phase II design. The treatment was reported as safe and well tolerated, and significantly reduced production of TNF-alpha, a pro-inflammatory cytokine, by immune cells from treated patients.

Regulatory Status

Despite decades of interest and clinical trial activity, VIP-based drugs have faced persistent development challenges — chiefly poor metabolic stability (VIP is broken down quickly in the body) and difficulty achieving effective concentrations at the target tissue. As of this writing, no VIP-based drug has reached the kind of broad approval seen with, for example, the GLP-1 drug class.

Limitations of the Current Evidence

  • The cited trial is small (20 subjects), open-label (no blinding or placebo control), and specific to sarcoidosis — findings should not be generalized to other conditions VIP is sometimes discussed for.
  • VIP's poor natural stability means results with modified or stabilized analogs (which is often what's actually being studied or sold) may not translate directly from studies of native VIP, or vice versa.

Research-Setting Dosing (as reported in literature)

RouteRange (as reported)FrequencyNotes
Inhalation (nebulized)—Over a 4-week treatment coursePrasse et al. (2010); the abstract we reviewed did not specify an exact per-dose amount, only route and duration. VIP inhalation was reported as safe and well tolerated, with reduced TNF-alpha production in treated sarcoidosis patients.

Figures above are extracted directly from the cited preclinical/research literature. They describe what researchers administered to study subjects (frequently animal models) — they are not human dosing recommendations and are not medical advice.

Cited Studies

  • Inhaled vasoactive intestinal peptide exerts immunoregulatory effects in sarcoidosis

    Prasse A, Zissel G, Lützen N, Schupp J, Schmiedlin R, Gonzalez-Rey E, Rensing-Ehl A, Bacher G, Cavalli V, Bevec D, Delgado M, Müller-Quernheim J · American Journal of Respiratory and Critical Care Medicine · 2010

    Human clinical trial (open-label Phase II, 20 subjects)View source →

Last updated August 1, 2026