[Doxazosin in the gastrointestinal therapeutic system (GITS) and doxazosin standard in patients with benign prostatic hyperplasia. Double-blind trial of efficacy and tolerability].

Abstract

Background and method: This randomized, doubleblind, multicenter, parallel-group, placebo-baseline study compared the effects of doxazosin GITS 4 mg or 8 mg once daily with doxazosin standard 1 mg to 8 mg once daily in 678 men with benign prostatic hyperplasia (BPH). Following a 2-week washout period and a 2-week, single-blind, placebo run-in phase, patients were randomized to 13 weeks of double-blind treatment with doxazosin GITS, initiated at 4 mg once daily and titrated to 8 mg once daily after 7 weeks, if needed, and doxazosin standard, initiated at 1 mg once daily, titrated to 2 mg after 1 week, to 4 mg at 3 weeks, and to 8 mg at 7 weeks if needed. The primary outcome measures were mean changes from baseline to the final visit for International Prostate Symptom Score (I-PSS) and maximum urinary flow rate in the per-protocol analysis (PPA) population. Secondary outcomes included other aspects of BPH symptoms and urinary flow; and assessment of sexual function in the PPA and intent-to-treat populations, as measured by the International Index of Erectile Function (IIEF).

Results: Doxazosin GITS and doxazosin standard produced clinically and statistically significant equivalent reductions in BPH symptoms, including least-square mean decreases in total I-PSS of -8.1 +/- 0.3 and -7.9 +/- 0.3 from baseline, respectively (p < 0.001 vs baseline for each). Both therapies significantly improved maximum urinary flow rates by 2.7 +/- 0.3 ml/s (least-squares mean change from baseline, p < 0.001). The beneficial effects of both therapies on secondary parameters of symptoms and urinary flow were consistent with these findings. Significant improvements in sexual function were observed with both therapies among individuals with sexual dysfunction at baseline. Nearly half of patients on doxazosin GITS achieved BPH symptom relief at the initial 4-mg dose.A similar number of patients in both doxazosin groups were titrated to the maximum dose of 8 mg for both formulations. While both agents were well tolerated, the incidence of at least one treatment-emergent adverse event was significantly lower among patients treated with doxazosin GITS (p = 0.003).

Conclusions: Doxazosin GITS and doxazosin standard produced comparable significant reductions in BPH symptoms and improvements in maximum urinary flow rates. A therapeutic effect equivalent to that of doxazosin standard was achieved with doxazosin GITS with fewer titration steps and enhanced tolerability. Both formulations of doxazosin improved sexual function in individuals with dysfunction at baseline.