Neuropeptide

VIP - vasoactive intestinal peptide - is a 28-amino-acid neuropeptide the body makes, densely present in the lung, where it relaxes smooth muscle, dilates pulmonary vessels and restrains inflammation. As a drug it is called aviptadil, and it has been tried in three quite different settings with three different outcomes. Inhaled VIP in sarcoidosis was safe and produced measurable immunoregulatory effects in an open phase 2 study. Inhaled aviptadil in pulmonary hypertension gave modest haemodynamic changes in a 20-patient study. And in COVID-19 respiratory failure, one 196-patient randomised trial reported a survival benefit at 60 days while the larger, better-powered TESICO trial found nothing. That sequence - promising small trial, null large trial - is the most informative thing about it.