Hermanns, T. et al. Is there a role for tamsulosin in the treatment of distal ureteral stones of 7 mm or less? Results of a randomised, double-blind, placebo-controlled trial. Eur. Urol. doi:10.1016/j.eururo.2009.03.076

The α-blocker tamsulosin has failed to enhance the likelihood of passage of distal ureteral calculi in one of the few randomized, double-blind, placebo-controlled trials of 'medical expulsive therapy' (MET). This contradicts the results of previous randomized—but not double-blinded and placebo-controlled—studies.

Differences in stone size might underlie the contrasting findings of different trials. “It is important to realize that the median stone size in our study was 3.9 mm; that is, rather small and thus prone [to] spontaneous ... expulsion,” notes senior author Räto Strebel from the University of Zurich.

A total of 100 patients were included in the Swiss study. Calculi located at the ureterovesical junction were more likely to be spontaneously passed than those in more-distal sections of the ureter, as were stones measuring ≤5 mm. When stratified by intervention, the overall stone expulsion rate was 86.7% in the tamsulosin group and 88.9% in the placebo group. No major complications occurred. Less than 10% of those treated with tamsulosin reported adverse effects, including mild diarrhea and retrograde ejaculation.

Interestingly, patients treated with tamsulosin passed their stone 3 days sooner, on average, than their counterparts in the placebo arm (7 versus 10 days). This secondary outcome did not reach statistical significance, however. Markedly less pain relief was required by those taking tamsulosin during the 21-day study period (P = 0.011). Tamsulosin has been reported to have an analgesic effect, and the shorter time to calculi expulsion might also have reduced inflammation and ameliorated pain.

The only other randomized, double-blind, placebo-controlled trial of an α-blocker for stone passage drew a similar conclusion to the current study with respect to expulsion rate. Again, stone size in the study of alfuzosin by Renato Nardi Pedro and colleagues was <5 mm. “Future research should focus on stones >5 mm in size. It is urgent to perform a proper study in this patient population to investigate the true value of MET with tamsulosin,” concludes Strebel.