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Research profile · Peptide

VIP

Also known as Vasoactive intestinal peptide, Aviptadil

Clinical — evidence level 4 of 4: Established clinical evidencePrescription only — UK regulatory status: Prescription-only medicine (UK)

Overview

A 28-amino-acid neuropeptide of the secretin family. Its synthetic form is a component of a UK prescription-only medicine.

Category
Peptide
Highest evidence level identified
Established clinical evidence
Last scientifically reviewed
22 August 2026
Last regulatory review
22 August 2026

Mechanism under investigation

Vasoactive intestinal peptide was isolated from porcine intestine in 1970 on the strength of its vasodilator activity, and turned out to be a widely distributed neuropeptide of the secretin/glucagon family. It signals through two class-B G-protein-coupled receptors, VPAC1 and VPAC2, which it shares with the related peptide PACAP, raising cAMP in target cells. Its documented physiology spans smooth-muscle relaxation, stimulation of intestinal secretion, bronchodilation, circadian synchronisation in the suprachiasmatic nucleus and immunomodulation. The synthetic form, aviptadil, is combined with phentolamine in the licensed product.

Research areas

  • Neuroendocrinology
  • Immunomodulation

These are fields in which the compound has been investigated. Listing a field is not a statement that anything was demonstrated within it.

Current evidence

In-vitro evidence

Cells, tissues or biochemical systems outside a living organism.

Extensive receptor pharmacology, consolidated in the IUPHAR review of VPAC and PAC1 receptors — cloning, ligand selectivity, signalling and distribution.

Animal evidence

Studies in living non-human animals.

Broad classical physiology across gut, airway, vascular and circadian systems; VIP-knockout mice show disturbed circadian rhythmicity and airway pathology, tying the peptide to its receptor biology in vivo.

Human observational evidence

Studies observing people without assigning an intervention.

Human tissue mapping and disease-association work, including the VIP-secreting tumour syndrome that first fixed the peptide’s clinical identity.

Clinical-trial evidence

Studies assigning an intervention to human participants.

The licensed evidence base is for injectable aviptadil with phentolamine in erectile dysfunction, assessed and accepted by UK and Scottish authorities. Trials of intravenous aviptadil in critical illness during the COVID period did not establish benefit, and inhaled and systemic uses in airway disease remain investigational.

Study limitations

  • The peptide’s breadth of action is the research problem: activity nearly everywhere means selectivity nowhere, and systemic administration produces flushing and hypotension at modest doses.
  • Native VIP is degraded within minutes in circulation, so most therapeutic hopes rest on analogues or formulations rather than the peptide itself.
  • The licensed indication is narrow and the product is combined with a second vasoactive drug; nothing reads across to other routes or uses.
  • The critical-care trials of aviptadil were conducted under pandemic conditions and did not demonstrate efficacy.

UK regulatory context

Prescription-only medicine (UK)

A medicine that may lawfully be supplied in the UK only against a prescription from an appropriate practitioner.

Source: Aviptadil/phentolamine mesilate (Invicorp) — Scottish Medicines Consortium advice (opens scottishmedicines.org.uk in a new tab) (Scottish Medicines Consortium)

Regulatory classification is jurisdiction-specific. A compound authorised elsewhere is not thereby authorised in the UK, and a supplier’s description of a substance does not determine how it is classified in law. See safety and regulation for the framework and the authoritative sources.

Safety and interpretation

Synthetic VIP is the active substance aviptadil in Invicorp, a UK prescription-only medicine given by intracavernosal injection for erectile dysfunction after specialist assessment — a licensed use that says nothing about systemic administration. Given intravenously, VIP is a potent vasodilator: flushing and blood-pressure fall are its documented pharmacology, and the one large recent systemic-use programme, in ventilated COVID patients, did not show benefit. Outside the licensed product there is no UK authorisation for any VIP preparation and no controlled safety dataset for repeated use.

References