Efficacy and safety of the doxazosin gastrointestinal therapeutic system for the treatment of benign prostate hyperplasia

This study was carried out to obtain information on the efficacy and safety of the controlled release formulation of the doxazosin Gastrointestinal Therapeutic System (GITS) in Taiwanese subjects with benign prostatic hyperplasia (BPH). Studies of doxazosin in Asian populations for this indication have lacked data particularly from Taiwan. This was an 8-week, post-marketing, open-label, non-comparative study. Eighty male subjects (mean age=64 years) with BPH received doxazosin GITS 4 mg once daily. At week 4, subjects who achieved an increase in maximum urinary flow rate (Qmax) of >3 mL/s and a >30 reduction in the total International Prostate Symptom Score (IPSS) continued on doxazosin GITS 4 mg for the remaining 4 weeks; all other subjects were up-titrated to 8mg once daily. Change from baseline at weeks 4 and 8 (primary endpoint) in IPSS and Qmax was evaluated using two-sided paired t tests for the intent-to-treat population. Safety was assessed throughout the study. A total of 53 (66.3) subjects completed the study. Baseline Qmax and IPSS were 10.7+3.4 mL/s and 20.6+5.4, respectively. At week 8, a significant increase from baseline in Qmax of 3.3+4.6 mL/s (95 confidence interval = 2.2-4.4, p< 0.001) and a significant decrease in total IPSS of -8.9 + 7.0 (95 confidence interval=-10.5 to -7.3, p< 0.001) was observed. The most common treatment-related adverse event was dizziness. Doxazosin GITS 4 mg per day (with an 8-mg titration step) effectively improved symptoms of BPH. The results from this study provide further information for clinicians on the use of doxazosin GITS for the treatment of BPH, particularly in Taiwanese patients.