Investigating the effect of sildenafil on improving lung function and quality of life in the patients with severe asthma

INTRODUCTION: Phosphodiesterase inhibitors (PDEs) increase intracellular cyclic adenosine monophosphate, which results in a wide range of anti-inflammatory effects and pathologically leads to improve asthma disease. Because no human study has surveyed the effect of PDEs on pulmonary function, except some case reports and animal researches, we decided to perform a pilot study for evaluating the effect of sildenafil (PDE5) on pulmonary function in patients with severe asthma. METHODS: This randomized controlled trials study was conducted on 20 patients with severe asthma in 2019 in Iran. For case group, was prescribed sildenafil (50 mg) daily and the control group received the placebo. In the beginning of the study and one month later, volume parameters, 6-minute walk distance (6MWD), and the quality-of-life questionnaire were measured and compared in the two groups. RESULTS: Twenty patients were entered into this study. 8 patients (40%) were male and 12 (60%) were female. The results showed that mean forced vital capacity 1 in the sildenafil group turned from 1259 ± 170 to 1603 ± 527, while in the placebo group it changed from 1135 ± 125 to 1365 ± 251 (P-value = 0.215). There is no statistically significant difference between two groups. In addition, in comparison with placebo, sildenafil did not show any significant improvement in the volume parameters, the quality-of-life questionnaire scale, and 6MWD at the end of the study. CONCLUSION: According to present result can be concluded that sildenafil does not improve the severity of asthma and the quality of life in patients with severe asthma.