Role of Phosphodiesterase 5 Inhibitors (PDE5i) (Sildenafil) in Management of Distal Ureteral Stone

Urolithiasis is one of the most common urological diseases. The risk of urolithiasis is estimated to be between 5% and 12% all over the world with increased incidence in male rather than female (2:1) respectively . Ureteral stones account for 20% from all urinary tract stones, more than 70% of the ureteral stones found in the lower third of the ureter . The incidence of urinary stones has been increasing day by day. Medical expulsive therapy (MET) of ureteral stones is the investigators' concern in this study. Stone location, size, number, ureteral spasm, mucosal edema or inflammation and ureteral anatomy are the factors affecting passage of the ureteral stones. So, MET is based on mechanism that stone passage is facilitated by the relaxation of ureteral smooth muscle , increasing hydrostatic pressure proximal to the stone and decreasing exciting edema . There are many oral medication could be used as MET such as adrenergic blockers, calcium channel blockers, prostaglandin synthesis inhibitors, glyceryl trinitrate and steroid treatment . Calcium-channel blockers and adrenergic α-antagonists are the main that has been proposed to enhance stone passage as expulsive medical therapy. Cyclic nucleotides are degraded by phosphodiesterases enzymes (PDEs). So using of PDE inhibtors may play role in relaxation of smooth muscle of the ureter. A study was done for evaluation of three PDE5 inhibtors, sildenafil , vardenafil and tadalafil, they found that PDE5 inhibitors can reverse the tension of isolated human ureteral smooth muscle via cGMP-mediated pathways.