Efficacy and tolerability of tamsulosin 0.4 mg in Asian patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia refractory to tamsulosin 0.2 mg: a randomized placebo controlled trial.

OBJECTIVE

To evaluate the efficacy and safety of tamsulosin dose increase to 0.4 mg daily in Asian patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia refractory to tamsulosin 0.2 mg treatment.

METHODS

We carried out a 12-week, single-center, randomized, placebo-controlled trial in 220 patients. Patients treated with 0.2 mg tamsulosin daily without other lower urinary tract symptoms secondary to benign prostatic hyperplasia medication for more than 3 months and refractory to this treatment were enrolled. We defined "refractory" as an International Prostate Symptom Score of 13 or greater and a maximum flow rate of 15 or under despite medication. Patients with a surgical history related to lower urinary tract symptoms secondary to benign prostatic hyperplasia or a postvoid residual of 150 mL or greater were excluded. Eligible patients were randomly assigned to the 0.4 mg group (two tablets of 0.2 mg tamsulosin once daily) or the 0.2 mg group (one tablet of 0.2 mg tamsulosin and one tablet of placebo once daily). International Prostate Symptom Score, maximum flow rate, blood pressure, heart rate, and adverse events were compared between the two groups at 4 weeks and 12 weeks.

RESULTS

A total of 220 patients were enrolled and analyzed. There were no differences in baseline characteristics between the two groups. After 12 weeks of medication, the International Prostate Symptom Score was not different between the two groups. However, the improvement in maximum flow rate was greater in the 0.4 mg group than the 0.2 mg group (3.0 ± 0.48 mL/s vs -0.25 ± 0.30 mL/s, P < 0.01). The proportion of patients who showed an increase in maximum flow rate of more than 5 mL/s was 10.9% in the 0.2 mg group versus 16.3% in the 0.4 mg group (P = 0.209). There were no significant differences in bother score or postvoid residual between the two groups. Systolic and diastolic blood pressure, and heart rate were also not different between the two groups. The incidence of adverse events was 10.9% in the 0.2 mg group (dizziness 5.5%; abnormal ejaculation 1.8%; palpitation 1.8%; and headache 1.8%) and 9.09% in the 0.4 mg group (dizziness 3.6%; abnormal ejaculation 1.8%; palpitations 1.8%; and headache 1.8%).

CONCLUSIONS

Tamsulosin 0.4 mg appears to be a safe treatment regimen for treating lower urinary tract symptoms secondary to benign prostatic hyperplasia in Asian patients who do not respond to 0.2 mg treatment. Increasing the dose of tamsulosin results in a significant improvement in maximum flow rate without any increase in cardiovascular complications.