Sildenafil Citrate Does Not Affect QT Intervals and QT Dispersion: An Important Observation for Drug Safety

Background: Sildenafil is an effective and widely used therapeutic agent for erectile dysfunction. Deaths have been reported due to sildenafil use and most of them are attributed to concurrent use of nitrates. However, the effects of sildenafil on QT intervals, QT dispersion, and the possible risk of ventricular arrhythmia have not been studied before. Our aim in this study was to evaluate the effect of sildenafil citrate on QT intervals and QT dispersion. Methods: Thirty‐six patients with erectile dysfunction were included in this study. Twenty‐one patients had coronary artery disease whereas 12 of them also had accompanying diabetes mellitus. Standard 12‐lead electrocardiograms (ECG) were recorded three times: before, and at the first and fourth hours of 50 mg sildenafil citrate ingestion. All QT parameters were corrected for heart rate. Results: Mean age of the patients was 54 ± 12 years. The mean heart rate did not differ significantly between the three ECG examinations. The corrected and uncorrected maximum and minimum QT intervals were not significantly different between the three ECG examinations. The QT dispersion and corrected QT dispersion before and 1 hour and 4 hours after sildenafil ingestion were 31 ± 9 ms, 36 ± 10 ms; 32 ± 11 ms, 37 ± 14 ms; 27 ± 8 ms, 32 ± 9 ms, respectively (P > 0.05). Conclusions: Sildenafil does not prolong QT intervals or increase QT dispersion in patients with erectile dysfunction. Our results suggest that the risk of ventricular arrhythmia does not increase with ingestion of 50 mg sildenafil.