Papaverine, a vasodilator with antiviral activity

We read with interest the excellent case report of Speich et al. concerning a 37-yearold patient with pulmonary arterial hypertension and HIV infection [1]. The patient’s pulmonary hypertension improved clinically after treatment with a combination of a nucleoside analogue and a protease inhibitor, and no vasodilatory therapy was necessary. However, if a vasodilator is considered of potential use in HIV patients with pulmonary arterial hypertension, papaverine may be a suitable therapeutic approach. Papaverine, a potent non-selective phosphodiesterase inhibitor, has shown itself to be effective in pulmonary arterial hypertension [2, 3]. The compound has additional antiviral activity against respiratory syncytial virus, cytomegalovirus or measles [4, 5]. Moreover, HIV replication is significantly inhibited by papaverine [5, 6], a finding consistent with the clinical observation that papaverine may improve immunological cutaneous responsiveness in acquired immunodeficiency syndrome [7]. The antiviral effect of papaverine is obviously independent of the increase in intracellular C-AMP and affects neither Il-2 production nor Il-2 receptor expression. Although its biological antiviral mechanism is not completely elucidated, papaverine may offer an alternative warranting further investigation in HIV patients with pulmonary hypertension. Horst J. Koch – Department of Psychiatry, University Hospital Regensburg, Germany Christoph Raschka– Institute of Sports Medicine, Frankfurt, Germany