Doxazosin and tamsulosin are worldwide available and widely used α1-adrenoceptor antagonists (α1-blockers) for the treatment of lower urinary tract symptoms (LUTS) in adult men. Randomized, controlled trials (RCTs) showed that α1-blockers reduce LUTS, as measured by the International Prostate Symptom Score (IPSS, range 0-35), by 30-40% independent on baseline LUTS severity. The American Urological Association (AUA) guidelines on the “Management of Benign Prostatic Hyperplasia” and the European Association of Urology (EAU) guidelines on the “Treatment on non-neurogenic male LUTS” both state that all α1-blockers have a similar clinical effectiveness but differ in tolerability when used in appropriate doses. [1, 2] However, these statements are based on indirect comparisons and only few direct comparisons between different α1-blockers. To test this hypothesis, we compared the efficacy and safety of different doses and formulations of doxazosin (immediate release 2 mg, 4 mg or 8 mg and gastrointestinal therapeutic system [GITS] 4 mg or 8 mg) versus tamsulosin (modified release 0.2 mg, 0.4 mg, 0.8 mg or oral controlled absorption System [OCAS] 0.4 mg) in a network meta-analysis of clinical trial data.

The PubMed, EMBASE and Cochrane databases were systematically searched to identify randomized, controlled clinical trials with doxazosin or tamsulosin. Bayesian random effects models estimated efficacy and safety outcomes, including total IPSS (IPSS-T), IPSS-quality of life (QoL) and any adverse events (AEs). Comprehensive assessments, including tests for heterogeneity, similarity, and consistency ensured unbiased and accurate estimates.

In total, 1,518 abstracts on doxazosin and/or tamsulosin were identified and reviewed of which 40 trials with 12,201 patients were included in our analyses. Improvement of IPSS-T and QoL (mean [95% credible interval, CrI]) were largest for doxazosin GITS 4 mg (IPSS-T: -10.08 points [-12.00, -8.21]; QoL: (-1.82 points [-2.25, -1.38]). Mean probability of any AE ranged from 0.15 to 0.40. Treatment comparisons are presented in the Table 1 (attached as image).

Our findings suggest for the first time that improvements in IPSS-T and QoL were significantly greater and the adverse event rates were similar for doxazosin GITS 4 mg compared with most tamsulosin formulations.

Contrary to the AUA and EAU guidelines statements, we found significantly greater clinical effectiveness in terms of total IPSS decrease and QoL increase for doxazosin GITS 4 mg compared with tamsulosin but a similar frequency of AEs.

McVary KT, Roehrborn CG, Avins AL, et al. Management of Benign Prostatic Hyperplasia (BPH). http://www.auanet.org/guidelines/benign-prostatic-hyperplasia-(2010-reviewed-and-validity-confirmed-2014).
Gravas S, Cornu JN, Drake MJ, et al. EAU Guidelines on the treatment of non-neurogenic male LUTS. http://uroweb.org/guideline/treatment-of-non-neurogenic-male-luts/?type=summary-of-changes.