title: Safety and long-term efficacy of transition from sildenafil to tadalafil due to side effects in patients with pulmonary arterial hypertension.
abstract: BACKGROUND
  Two phosphodiesterase-type 5 (PDE-5) inhibitors, sildenafil and tadalafil, are approved for treatment of pulmonary arterial hypertension (PAH). It has not yet been observed if transition from sildenafil to tadalafil is beneficial in patients suffering from adverse reactions. Aim of this study was to analyze safety 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 min walking distance (6MWD), echocardiography, lung function tests, and NTproBNP pre-transition and 3, 6, and 12 months post-transition.
  
  
  RESULTS
  Included were 13 PAH patients (8 females mean age 64 ± 10 years) who had been on sildenafil for a mean of 12 ± 8.4 months. In six patients (46.1 %) 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 (38.5 %) adverse events occurred under tadalafil as well and therapy with PDE-5 inhibitors was discontinued. In two patients (15.4 %) sildenafil-treatment could be successfully restarted after an intermittent switch to tadalafil.
  
  
  CONCLUSIONS
  The observations of this study indicate that a transition of sildenafil to tadalafil in case of intolerable side effects is a reasonable therapy option in about 50 % of the patients. These results should be verified by a larger prospective study.
authors.affiliation: Centre for Pulmonary Hypertension, Thoraxklinik of University Hospital Heidelberg, Amalienstrasse 5, 69126, Heidelberg, Germany, mona.lichtblau@med.uni-heidelberg.de.
authors.forename: Mona
authors.initials: M
authors.lastname: Lichtblau
authors.forename: Dominik
authors.initials: D
authors.lastname: Harzheim
authors.forename: Nicola
authors.initials: N
authors.lastname: Ehlken
authors.forename: Alberto
authors.initials: A
authors.lastname: Marra
authors.forename: Fabiola Pena
authors.initials: FP
authors.lastname: Pinado
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Grünig
authors.forename: Benjamin
authors.initials: B
authors.lastname: Egenlauf
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D062186:Arterial Pressure / Q000187:drug effects*; D002243:Carbolines / Q000009:adverse effects / Q000627:therapeutic use*; D057915:Drug Substitution; D017079:Exercise Tolerance / Q000187:drug effects; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D058986:Phosphodiesterase 5 Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use*; D011651:Pulmonary Artery / Q000187:drug effects* / Q000503:physiopathology; D011687:Purines / Q000009:adverse effects / Q000627:therapeutic use; D012189:Retrospective Studies; D000068677:Sildenafil Citrate; D013449:Sulfonamides / Q000009:adverse effects / Q000627:therapeutic use*; D000068581:Tadalafil; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents; D002243:Carbolines; D058986:Phosphodiesterase 5 Inhibitors; D010879:Piperazines; D011687:Purines; D013449:Sulfonamides; D000068581:Tadalafil; D000068677:Sildenafil Citrate