The association between vardenafil plasma concentration and change in mPAP (A) and PVR (B) at 60 min after a single oral dose of vardenafil in patients with pulmonary hypertension (n = 16). Thirteen patients received 20 mg of vardenafil ( and □), two patients received 10 mg (▴) and one patient received 5 mg (○). Open squares indicates patients exposed to bosentan (n = 3). Plasma vardenafil and change in mPAP and PVR correlated significantly (Spearman rank correlation r = −0.579, n = 16, P = 0.019 for mPAP and r = −0.662, n = 16, P = 0.005 for PVR)