A placebo-controlled double-blind study of the effect of phenoxybenzamine in benign prostatic obstruction.

A double-blind placebo-controlled study of phenoxybenzamine for the symptomatic treatment of benign prostatic obstruction is reported. Statistically significant evidence of an improvement in both the peak and mean flow-rates was found. Both diurnal and nocturnal frequency were significantly diminished. Residual urine was unaffected, and the possible reasons for this are discussed. Urethral pressure recordings confirmed the reduction in the closure pressure in the prostatic segment of the urethra. It was concluded that there was good evidence that the treatment is effective.