Clinical comparison of selective and non-selective alpha 1A-adrenoreceptor antagonists in benign prostatic hyperplasia: studies on tamsulosin in a fixed dose and terazosin in increasing doses.

OBJECTIVE

To compare the efficacy and safety of a fixed dose (0.2 mg) of tamsulosin, a selective alpha 1A-adrenoreceptor antagonist, with an increasing dose (1-5 mg) of terazosin, a non-selective antagonist, in the treatment of urinary outflow obstruction associated with benign prostatic hyperplasia (BPH) in Korean patients.

PATIENTS AND METHODS

The study comprised a single-blind and randomized design with tamsulosin or terazosin taken once daily for 8 weeks. A total of 98 patients was enrolled, with 72 patients included in the analyses after 4 and 8 weeks. The primary variables assessed were changes in the maximum urinary flow rate Qmax and the total International Prostate Symptom Score (IPSS), with the post-void residual urine volume, 'obstructive' and 'irritative' questions in the IPSS, and the investigators' global assessment of efficacy also determined. The number of patients with a clinically significant response to treatment with tamsulosin or terazosin was determined and defined as those with > 20% improvement from the baseline Qmax or > 20% decrease in total IPSS. Adverse reactions possibly or probably related to study medication were recorded throughout the treatment period.

RESULTS

Both tamsulosin and terazosin produced similar significant improvements in subjective and objective symptoms of urinary outflow obstruction (P > 0.05). Systolic and diastolic (standing) blood pressures decreased significantly in patients treated with terazosin (P < 0.05). The adverse reactions, most frequently dry mouth and dizziness which were usually mild and transient, were significantly higher in patients on terazosin (18 patients, versus one on tamsulosin, P < 0.001). The changes led to discontinuation of therapy in two patients on terazosin.

CONCLUSION

Tamsulosin was as effective as terazosin in treating urinary outflow obstruction associated with BPH, but had a markedly better safety profile.