Figure 1.

In 10 patients with pulmonary arterial hypertension (PAH) who were stabilized on 20 mg oral sildenafil three times daily and had their morning oral sildenafil dose replaced with a 10 mg bolus intravenous sildenafil dose, individual sildenafil plasma concentrations after the bolus dose are shown (continuous lines). These are superimposed on plasma concentrations associated with oral sildenafil 20 mg three times daily dosing in a population pharmacokinetic model established using the data from 206 patients with PAH in a multinational, randomized, double-blind, placebo-controlled trial to evaluate the safety and efficacy of oral sildenafil (20, 40 or 80 mg three times daily) over a 12 week period: 95% range of the individual predicted concentrations (hatched area) and the mean concentration time profile (bold dashed black line) [6, 7].