Rapaflo (silodosin) was more effective than Cialis (tadalafil) in improving lower urinary tract symptoms (LUTS) caused by prostate enlargement in a study comparing the two drugs, though Rapaflo caused more adverse reactions.

The study, “Comparison of Silodosin versus Tadalafil in Patients with Lower Urinary Tract Symptoms Associated with Benign Prostatic Hyperplasia,“ appeared in the journal LUTS: Lower Urinary Tract Symptoms. It showed that when men switched from Cialis to Rapaflo, their quality of life improved rapidly.

Researchers at Japan’s National Center for Geriatrics and Gerontology noted that although several trials have compared the effects of Cialis and Flomax (tamsulosin), none had looked at the differences between Cialis and Rapaflo, which belongs to the same class of drugs as Flomax.

Researchers in this study assigned 188 men to two randomly assigned groups. One received either 8 mg of Rapaflo per day , the other 5 mg of Cialis per day, for eight weeks. The study was not blinded, meaning that both patients and study staff knew which drug each patient was taking.

Those on Cialis during the first eight weeks were then re-randomized to either continue with Cialis or switch to Rapaflo for another eight weeks of treatment. After the first treatment period, 78.7 percent of men on Rapaflo responded to treatment, compared to 69.6 percent for Cialis — not a statistically significant difference.

Those receiving Rapaflo improved by 10.1 points on the International Prostate Symptoms Score (IPSS) scale, while Cialis patients improved by 8 points, which was significantly less. Specifically, symptoms of incomplete bladder emptying, weak stream and nighttime urination improved more with Rapaflo than Cialis. Other symptoms had improved to a numerically greater extent in the Rapaflo group, but the difference was not significant.

Both groups saw their quality of life improve, though the improvement was larger for men treated with Rapaflo.

During the second study period, the IPSS symptoms scores of patients who switched to Rapaflo dropped more rapidly. But by the end of the trial, the two groups of patients had a similar change in symptoms, measured from the start of the second study period. Likewise, researchers saw quality of life improvements after two weeks on Rapaflo and four weeks on Cialis in the second study period.

The trial did not include a group treated with Rapaflo over 16 weeks, so differences over the longer term were not studied.

In all, 23.4 percent of men on Rapaflo and 8.4 percent of men on Cialis reported side effects. While both groups experienced dizziness, headache and gastrointestinal problems, only Rapaflo use was linked to orthostatic hypotension (low blood pressure when standing up), nasal congestion, ejaculation difficulties and retrograde ejaculation. Those side effects led three men on Rapaflo and one on Cialis to stop treatment altogether.