Sildenafil And Hypoxic Pulmonary Hypertension

We have previously demonstrated that sildenafil inhibits hypoxia-induced pulmonary vasoconstriction in healthy subjects. The aim of this study was to investigate the effects of the PDE5 inhibitor sildenafil on pulmonary hemodynamics in patients with high altitude pulmonary hypertension (HAPH). Twenty-two patients with HAPH were randomized by age and level of mean pulmonary arterial pressure (PAP) in 3 groups: a first group (n=9) treated with 25mg of sildenafil 3 times a day; a second group (n=5) - received 100mg of sildenafil 3 times a day; a third group (n=8) - treated with placebo. Pulmonary hemodynamics was measured by right heart catheterization at baseline and after 12 weeks of sildenafil therapy at, before and 1 hour after taking sildenafil or placebo. In the first group the mean PAP decreased after 12 weeks of sildenafil treatment from 36 8 to 30 8mm Hg and to 25 7mm Hg (p < 0.007) 1 hour after 25mg of sildenafil, in the second group, mean PAP decreased after 12 weeks from 32 3 to 26 3 mm Hg (p < 0.0 1) and to 21 2 mm Hg (P < 0.001) 1 hour after 100mg of sildenafil, in the third group the mean PAP did not significantly change. Both doses improved the 6-minute walk distance, in the first group of patients by 45.4 in (p < 0.0 1) and in the second group by 40. 0 in (p < 0. 049). No side effects were observed. We conclude that sildenafil therapy decreases PAP and could be recommended for treatment of HAPH.