Safety and long-term efficacy of transition from sildenafil to tadalafil due to side effects in patients with pulmonary arterial hypertension

Background: Two phosphodiesterase-type 5 (PDE-5) inhibitors, sildenafil and tadalafil, are an approved treatment of pulmonary arterial hypertension (PAH). It has not yet been observed if transition from sildenafil to tadalafil is beneficial in patients suffering adverse reactions. Aim of this study was to analyze feasibility and long-term effects in PAH patients whose treatment was transitioned from sildenafil to tadalafil due to intolerable side-effects. Methods: A retrospective analysis of PAH-patients who were stable on sildenafil for 3 months and transitioned to tadalafil due to adverse events was performed. Data collected included demographics, PAH-etiology, WHO-functional class, 6 minute walking distance (6MWD), echocardiography, lung function tests and NTproBNP pre-transition, 3, 6 and 12 months post-transition. Results: Included were 13 PAH patients (8 females, mean age 64±10years) who were on sildenafil for a mean of 12±8.4 months. In 6 patients a switch to tadalafil was feasible and resulted in tolerable side effects and a stable clinical course with improvement of symptoms, 6MWD, stable echocardiographic findings and NTproBNP-levels during a follow-up of 11±3 months. In 5 out of 13 patients adverse events occurred under tadalafil as well, therapy with PDE-5 inhibitors was discontinued. In 2 patients sildenafil-treatment could be successfully restarted after an intermittent switch to tadalafil. Conclusion: The observations of this study indicate that a transition of PDE-5 inhibitors due to intolerable side effects is reasonable in ∼50% of the patients. These results should be verified by a larger prospective study.