Investigators discovered these beneficial effects when they compared tadalafil with placebo in men with ED and BPH-related LUTS in a phase 3 randomized, double-blind trial. The researchers, led by Claus G. Roehrborn, MD, of the University of Texas Southwestern Medical School in Dallas, randomly assigned 200 men to receive placebo, 198 to receive tadalafil 2.5 mg, and 208 to receive tadalafil 5 mg once daily for 12 weeks. Tadalafil is a phosphodiesterase-5 inhibitor indicated for the treatment of ED.
To be included the study, the men need to have a total International Prostate Symptom Score (IPSS) of 13 or higher and peak urinary flow rate of 4-15 mL/sec. The researchers evaluated changes in IPSS as well in International Index of Erectile Function (IIEF) Erectile Function (IIEF EF) domain scores. Researchers presented findings at the 26th Annual Congress of the European Association of Urology.
At 12 weeks, Dr. Roehrborn’s group observed significant improvements in IIEF EF with both tadalafil doses compared with placebo. The score improved by a mean 1.8 points with placebo and by 5.2 and 6.5 points with tadalafil 2.5 and 5 mg, respectively.
Significant improvement in IPSS relative to placebo occurred only in the tadalafil 5 mg arm. The mean decrease in IPSS was 3.8 points in the placebo arm versus 6.1 points in the tadalafil 5 mg group.
The researchers also asked subjects to respond to question 3 of the Sexual Encounter Profile questionnaire (Did you erection last long enough for you to have sexual intercourse?). The number of “yes” responses increased by 12% in the placebo group compared with 24.6% and 31.7% in the tadalafil 2.5 and 5 mg groups, respectively. The differences between both of the tadalafil groups and the placebo group were statistically significant.
The researchers also assessed patients using the BPH Impact Index and found that tadalafil 5 mg, but not tadalafil 2.5 mg, was significantly associated with improvement compared with placebo. The placebo group had a 1.2 point decrease in score compared with a 2.1 decrease in the tadalafil 5 mg group.
The most common treatment-emergent adverse events with tadalafil (occurring in 2% or more of patients) were headache, back pain, and nasopharyngitis. Most of these events were mild to moderate in severity. The investigators observed no evidence of urinary retention or adverse impact of tadalafil on orthostatic vital signs.