Safety, tolerability, and efficacy of overnight switching from sildenafil to tadalafil in patients with pulmonary arterial hypertension.

AIMS:Tadalafil, a once-daily phosphodiesterase type 5 inhibitor (PDE-5I), offers clinicians an alternative to sildenafil, a 3-times-daily (t.i.d.) PDE-5I for treatment of pulmonary arterial hypertension (PAH). However, there are limited data describing the risks and benefits or recommended methodology of switching patients from sildenafil to tadalafil. METHODS:Chart reviews were conducted on all World Health Organization group 1 patients on sildenafil for ≥ 3 months who transitioned to tadalafil with documented clinic visits and 6-min walk tests on both drugs. Most patients were transitioned by discontinuing sildenafil after the evening dose and initiating tadalafil 40 mg/day the next day. Data collected included demographics, PAH etiology, diagnostic hemodynamics, 6-min walk distance (6MWD), PDE-5I side effects, and concomitant medications. Data on B-type natriuretic peptide (BNP) levels were available for most patients also receiving endothelin receptor antagonists (ERAs). RESULTS:Medical records from 98 patients were evaluated. Most patients (92%) were on sildenafil for > 1 year, and 78% were receiving sildenafil 80-100 mg t.i.d. Ninety-seven percent of patients (95/98) were successfully transitioned and maintained on 40 mg/day. With a mean duration on tadalafil therapy of 243 ± 127 days at the time of analysis, 6MWD was unchanged. Patient-reported adverse events included headache (4%) and heartburn (2%). There was minimal change in BNP levels in the subset of patients receiving an ERA concomitantly. CONCLUSIONS:Transition from sildenafil to tadalafil 40 mg/day appears feasible without clinical deterioration or intolerable side effects. This study provides guidance to physicians considering transition from sildenafil to tadalafil for selecting patients.