Silodosin is a kind of α- adrenergic receptor antagonists developed by Japanese Kissei pharmaceutical company. It has a very good therapeutic efficacy on treating the dysuria related to benign prostatic hyperplasia. The selective effect on urethra of Silodosin is 12 times and 7.4 times as high as that of prazosin and tamsulosin, respectively, which can significantly inhibit norepinephrine-induced contraction of the prostate; it has dose-dependent inhibition bladder activity excitation in the benign prostatic hypertrophy models of rats, and can also improve the pressure threshold of bladder contraction. These data have suggested that, in addition to helping improve bladder function, silodosin is also effective in alleviating the related symptoms associated with benign prostatic hypertrophy.
Compared with similar drugs such as prazosin and tamsulosin, silodosin has a high selectivity onn theα1A- receptors located in the prostate and bladder neck, while having a low affinity to theα1B- and α1D-receptor. It can block theα1A- receptors in these sites, and relax the smooth muscle, and thus leading to the improvement of urinary flow rate and the alleviation of BPH symptoms.
The selective binding to the α1A-receptor by silodosin has a higher selectivity compared to the binding to the cardiovascular associated receptors α1B, thus maximizing the activity of the target organ as well as minimizing the potential effect on blood pressure.