Efficacy and safety of high dose generic sildenafil in thai patients with pulmonary arterial hypertension

Abstract

Objective: Sildenafil, an orally administered phosphodiesterase type 5 (PDE-5) inhibitor, was known for enhancing the downstream effects of NO. It was approved for treatment in patients with pulmonary arterial hypertension (PAH). Recently, a generic sildenafil (Unison Laboratories, Thailand) was proved to have the same bioequivalent as in the original formula. The authors conducted a 12-week case series to study the efficacy and safety of Elonza ® (generic sildenafil) in PAH patients. Material and Method: Comparison of both hemodynamic data from cardiac catheterization and clinical outcome such as six minute walk test (6MWT) were performed to assess the efficacy of generic sildenafil at the dosage of 50 mg given orally three times daily in patients with PAH over a 12 weeks period. Results: There were 20 patients whose average age was 31.4 ± 14.3 years old (13-58) and their average weight was 48.1 ± 11.9 kg (31-79). There were three idiopathic pulmonary artery hypertensions (IPAH) and 17 congenital left to right shunts. There was a 15.1% decrease in pulmonary vascular resistance index (PVRi) from 20.5 ± 13.9 to 17.4 ± 2.9 Wood unit m 2 at the end of 12 weeks (p = 0.044). The ratio of pulmonary to systemic vascular resistance (PVR/SVR) was also decreased from 0.71 ± 0.57 to 0.52 ± 0.41 (p = 0.014). 6MWT increased significantly from 271 + 59 meters (m) at baseline to 297 ± 48 m, 307 ± 43 m and 321 ± 52 m at week 2, 6 and 12, respectively (p = 0.01). There was no significant change in other hemodynamic parameter, Borg dyspnea score, and functional class. Conclusion: At the end of the 12-week treatment, a 50 mg three times daily of generic sildenafil given to patients with PAH was shown to have benefit on decreasing PVRi, PVR/SVR ratio. There was also an increase in mean average of 6MWT at the end of 12 weeks.