VIP — a Natural Peptide — Opens Airways and Blocks Histamine Reactions in Asthma Patients

What the researchers found

Intravenous VIP caused significant bronchodilation in all seven asthmatic volunteers and protected against histamine-induced bronchoconstriction in every subject. The dose was 6 pmol/kg/min infused over 15 minutes. Side effects included tachycardia (rapid heart rate) and cutaneous flushing during the infusion.

Why it matters

This was one of the first human studies demonstrating that VIP — a naturally occurring peptide — could open airways in asthma patients and block histamine-triggered airway narrowing. Published in The Lancet in 1983, it established VIP as a potential natural bronchodilator in humans and suggested an entirely new peptide-based approach to asthma treatment.

The numbers in context

n=7 asthmatic volunteers · 6 pmol/kg/min for 15 min · Bronchodilation in all subjects · Protection against histamine-induced bronchoconstriction in all subjects

How the study worked

Double-blind study in seven adult asthmatic volunteers. VIP was administered intravenously at 6 pmol/kg/min for 15 minutes. Bronchodilation was measured (likely by forced expiratory volume), and subjects were also challenged with histamine to test whether VIP could protect against bronchoconstriction.

What this study cannot tell us

Very small sample size (only 7 subjects). Intravenous delivery caused systemic side effects (tachycardia, flushing), making this route impractical for routine asthma treatment. The study did not test inhaled VIP, which would be the clinically relevant delivery method. Short duration — only a single 15-minute infusion was tested.

How to read the evidence

This is a small (n=7) double-blind human study published in The Lancet. While the double-blind design adds rigor, the very small sample size limits statistical power. It's best understood as early proof-of-concept rather than definitive clinical evidence.

When this study was published

Published in 1983, this is a foundational historical study — over 40 years old. VIP has not become a standard asthma treatment due to delivery challenges, but the study remains widely cited as key evidence for VIP's bronchodilatory properties in humans.

The bigger picture

VIP is one of the body's own bronchodilators, found in nerve fibers throughout the airways. This 1983 Lancet study helped establish the concept that endogenous peptides — not just synthetic drugs like salbutamol — could be therapeutic targets for asthma. While VIP itself proved difficult to develop as a drug (it breaks down rapidly and causes systemic side effects when given IV), it opened the door to research on peptide-based airway therapies and VIP analogs with better pharmacological properties.

Questions still open

• Could inhaled VIP or stabilized VIP analogs achieve bronchodilation without the systemic side effects seen with IV delivery?
• Is VIP deficiency in airway nerves a contributing factor in some forms of asthma?
• How does VIP's bronchodilatory mechanism compare to beta-agonists like salbutamol?

Common questions

Read the original research

Vasoactive intestinal peptide causes bronchodilatation and protects against histamine-induced bronchoconstriction in asthmatic subjects.

Lancet (London, England), 2(8361), 1225-7

Citation

Morice, A; Unwin, R J; Sever, P S. (1983). Vasoactive intestinal peptide causes bronchodilatation and protects against histamine-induced bronchoconstriction in asthmatic subjects.. Lancet (London, England), 2(8361), 1225-7.