Patients being treated with a combination 5-alpha reductase inhibitor (5ARIs) and an alpha blocker may switch to 5ARIs alone with no worsening of lower urinary tract symptoms (LUTS), a new study says. But in overweight patients, the withdrawal must be carefully monitored.

These findings, in the study “Effects of withdrawing alpha-1 blocker from the combination therapy with alpha-1 blocker and 5-alpha-reductase inhibitor in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia: A prospective and comparative trial using urodynamics,” were published in The Journal of Urology.

BPH treatments include alpha blockers, which have been shown to improve maximal flow rate and the quality of life of patients, and inhibitors of the enzyme 5-alpha reductase (5ARIs), such as Propecia (finasteride) and Avodart (dutasteride), which reduce the total prostate volume and surgical risk in long-term follow-ups.

Previous studies have shown that combining both alpha blockers and 5ARIs is effective in reducing LUTS, decreasing the total prostate volume, and reducing the risk of disease progression compared to treatment with a single medication.

Researchers wanted to test what happens when patients on a combination therapy switch to 5ARIs alone, and evaluate the changes in LUTS after therapy with alpha blockers is stopped.

To do so, the team analyzed 132 patients with LUTS who were receiving treatment with Rapaflo (silodosin) (alpha blocker, 8 mg/day) and Avodart (5ARI, 0.5 mg/day) for 12 months. Patients were then assigned to continue their treatment or switch to Avodart therapy alone for another 12 months. The efficacy analysis included 57 patients from the combo group and 60 from the single medication group.

Results showed that the change in the International Prostate Symptom Score (IPSS) after the treatment was -0.7 in the combo group and -0.6 in the 5ARI group.

Also, bladder outlet obstruction (BOO) index decreased from 46.1 to 41.8 in the combo group, and from 42.9 to 39.9 in the 5ARI group, but researchers found no significant differences between the two groups.

However, patients in the group taking 5ARI alone experienced a decrease in bladder storage. And LUTS significantly worsened in patients with a higher body mass index (BMI) after the alpha blocker was withdrawn.

“Although silodosin was withdrawn from combination therapy with silodosin and dutasteride for LUTS/BPH after 12 months, no significant differences were observed in the improvement of subjective symptoms and BOO between the patients continuing combination therapy and those who were switched to dutasteride monotherapy,” the researchers wrote. “However, LUTS significantly deteriorated after the switch to dutasteride monotherapy in patients with higher [body weight]. Therefore, withdrawal must be carefully performed for these patients.”