Effect of Shifting from Combination Therapy to Monotherapy of α-Blockers or 5α-Reductase Inhibitors on Prostate Volume and Symptoms in Patients with Benign Prostatic Hyperplasia

PURPOSE: Combination therapy of α-blockers and 5α-reductase inhibitors (5-ARIs) is widely used for the treatment of benign prostatic hyperplasia (BPH). We aimed to study the effect on prostate volume and symptoms of shifting to monotherapy in patients who previously received a combination therapy. MATERIALS AND METHODS: A prospective study was conducted of 60 patients who were diagnosed with BPH. Patients were aged 45 years or older and had a prostate volume of 30 cc or more, International Prostate Symptom Score (IPSS) of 12 or above, maximal flow rate (Qmax) of 15 ml/s or less, and prostate-specific antigen (PSA) level of less than 10 ng/ml. The patients initially received a combination therapy of doxazosin 4 mg/day and finasteride 5 mg/day for 3 months and were then randomly assigned to receive monotherapy for 3 months. The factors were then compared. RESULTS: A total of 30 patients were assigned to doxazosin (group 1) and 30 to finasteride (group 2) after the combination therapy. The percentage changes in prostate volume, IPSS, and Qmax during the period from post-combination therapy to post-monotherapy were not significantly different between the two groups (p=0.052, 0.908, 0.081), whereas PSA significantly decreased in group 2 (p<0.001). IPSS was not significantly different at post-combination therapy and at post-monotherapy in both groups (p=0.858, 0.071). The prostate volume significantly increased from 40.97 cc at post-combination therapy to 44.29 cc at post-monotherapy in group 1 (p=0.001) and insignificantly increased from 38.32 cc to 38.61 cc in group 2 (p=0.696). CONCLUSIONS: Although the duration of drug administration was short in this study, 5-ARI monotherapy could maintain the alleviated symptoms and reduce the risk of acute urinary retention and surgery due to prostate regrowth in BPH patients whose symptoms improved with combination therapy.