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

Objectives: To evaluate the efficacy and safety of tamsulosin dose increase to 0.4mg daily in Asian patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia refractory to tamsulosin 0.2mg treatment. Methods: We carried out a 12-week, single-center, randomized, placebo-controlled trial in 220 patients. Patients treated with 0.2mg tamsulosin daily without other lower urinary tract symptoms secondary to benign prostatic hyperplasia medication for more than 3months 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 150mL or greater were excluded. Eligible patients were randomly assigned to the 0.4mg group (two tablets of 0.2mg tamsulosin once daily) or the 0.2mg group (one tablet of 0.2mg 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 4weeks and 12weeks. Results: A total of 220 patients were enrolled and analyzed. There were no differences in baseline characteristics between the two groups. After 12weeks 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 0.4mg group than the 0.2mg group (3.0±0.48mL/s vs -0.25±0.30mL/s, P<0.01). The proportion of patients who showed an increase in maximum flow rate of more than 5mL/s was 10.9% in the 0.2mg group versus 16.3% in the 0.4mg 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 0.2mg group (dizziness 5.5%; abnormal ejaculation 1.8%; palpitation 1.8%; and headache 1.8%) and 9.09% in the 0.4mg group (dizziness 3.6%; abnormal ejaculation 1.8%; palpitations 1.8%; and headache 1.8%). Conclusions: Tamsulosin 0.4mg 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 0.2mg treatment. Increasing the dose of tamsulosin results in a significant improvement in maximum flow rate without any increase in cardiovascular complications.