Alpha Blockers for Management of Ureteric Calculi
Alpha blockers are the preferred agents for medical expulsive therapy (MET) in the management of ureteric calculi, with tamsulosin being the most commonly used, though tamsulosin, terazosin, and doxazosin appear equally effective. 1
Efficacy of Alpha Blockers for MET
Alpha blockers significantly increase stone passage rates by 29% (95% CI: 20% to 37%) compared to control treatments, making them superior to calcium channel blockers like nifedipine, which only increase passage rates by 9% (95% CI: 7% to 25%) 1
MET with alpha blockers not only increases stone passage rates but also reduces stone passage time and limits pain 1
The beneficial effects of alpha blockers are attributed to ureteral smooth muscle relaxation mediated through alpha-1 receptor blockade 1
Specific Alpha Blockers and Their Effectiveness
Tamsulosin has been the most extensively studied alpha blocker for ureteric calculi and is most commonly used in clinical practice 1
One small study demonstrated that tamsulosin, terazosin, and doxazosin are equally effective in facilitating stone passage 1, 2
For proximal ureteral calculi ≤6 mm, tamsulosin significantly increases stone expulsion rates (74.1% vs. 46.3% with conservative management) and shortens time to stone passage (14.3 days vs. 19.6 days) 3
For distal ureteric stones, tamsulosin has shown superior stone expulsion rates compared to alfuzosin (85% vs. 75%), with both being more effective than no alpha-blocker (44%) 4
Stone Size Considerations
Alpha blockers appear particularly beneficial for larger stones (5-10 mm), with one study showing tamsulosin increased passage rates to 83.3% compared to 61.0% with placebo, representing a number needed to treat of 4.5 5
For smaller stones (<5 mm), the benefit of alpha blockers may be less pronounced, as these stones have a higher likelihood of spontaneous passage 5
Clinical Application Guidelines
Patients should be counseled that alpha blockers are used "off-label" for MET and informed about potential side effects 1
MET with alpha blockers should only be used in patients with well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve 1
Patients should be followed with periodic imaging studies to monitor stone position and assess for hydronephrosis 1
For stones >10 mm, surgical intervention is typically required rather than MET alone 1
Caveats and Considerations
Not all studies show benefit with alpha blockers. One randomized controlled trial found no significant difference in spontaneous stone passage between tamsulosin and standard therapy (77.1% vs. 64.9%) for distal ureteral calculi with mean stone size of 3.6 mm 6
Side effects of alpha blockers are generally mild and transient, making them safe for most patients 4, 2
When choosing between alpha blockers and calcium channel blockers, alpha blockers provide a statistically significant 20% improvement in stone passage rates (95% CI: 1% to 37%) 1