Vasoactive Intestinal Peptide (VIP) is a neuropeptide, expressed by lymphoid as well as neural cells, which has diverse effects on the cellular mediators of inflammation and immunity and is also a potent neurotransmitter. VIP seems to have a major role in the homeostasis of the respiratory system, while several studies, including clinical trials, suggest that VIP-inhaled agonists could be used in respiratory therapeutics.

Mathioudakis A G, Chatzimavridou-Grigoriadou V, Evangelopoulou E, et al. Vasoactive intestinal peptide inhaled agonists: potential role in respiratory therapeutics[J]. Hippokratia, 2013, 17(1): 12.

Pulmonary hypertension (PH) leads to an increased right ventricular workload, cardiac failure and death. In idiopathic pulmonary arterial hypertension (PAH) the vasodilating vasoactive intestinal peptide (aviptadil) is deficient. The aim of the present study was to test the acute effects on haemodynamics and blood gases, and the safety, of a single dose of inhaled aviptadil in chronic PH. A total of 20 patients with PH (PAH in nine, PH in lung disease in eight and chronic thromboembolic PH in three) inhaled a single 100-microg dose of aviptadil during right-heart catheterisation. Haemodynamics and blood gases were measured. Aviptadil aerosol caused a small and temporary but significant selective pulmonary vasodilation, an improved stroke volume and mixed venous oxygen saturation. Overall, six patients experienced a pulmonary vascular resistance reduction of >20%. In patients with significant lung disease, aviptadil tended to improve oxygenation. The pulmonary vasodilating effect of aviptadil aerosol was modest and short-lived, did not cause any side-effects and led to a reduced workload of the right ventricle without affecting systemic blood pressure. Aviptadil inhalation tended to improve oxygenation in patients with significant lung disease. Further studies are needed to evaluate the full therapeutic potential of aviptadil aerosol, including higher doses and chronic treatment.

Leuchte H H, Baezner C, Baumgartner R A, et al. Inhalation of vasoactive intestinal peptide in pulmonary hypertension[J]. European Respiratory Journal, 2008, 32(5): 1289-1294.