From the Guidelines
Flomax (tamsulosin) is the preferred alpha blocker for medical expulsive therapy in patients with kidney stones, as it has been shown to facilitate and accelerate the spontaneous passage of ureteral stones. According to the 2007 guideline for the management of ureteral calculi 1, alpha blockers, such as tamsulosin, have been demonstrated to be effective in facilitating ureteral stone passage, with a statistically significant 29% more patients passing their stones compared to control patients.
The mechanism of action of alpha blockers, such as Flomax, is through the relaxation of ureteral smooth muscle, mediated by alpha-1 receptor blockade, which helps to reduce the stone-passage time and limit pain 1. The typical dose of Flomax for kidney stones is 0.4 mg taken once daily until the stone passes. It is essential to take Flomax about 30 minutes after the same meal each day and continue until the stone passes, usually within 2-4 weeks.
Some key points to consider when using Flomax for kidney stones include:
- Drinking plenty of water (at least 2-3 liters daily) to help flush the stone
- Being aware of common side effects, such as dizziness, headache, abnormal ejaculation, and a drop in blood pressure when standing up quickly
- Seeking immediate medical attention if symptoms such as severe pain, fever, or vomiting occur, as these may indicate complications requiring different treatment approaches
- Flomax is most effective for stones smaller than 10mm located in the lower part of the ureter 1.
From the Research
Efficacy of Flomax for Kidney Stones
- The studies 2, 3, 4, 5 suggest that alpha-blockers, such as tamsulosin (Flomax), may be effective in increasing stone clearance and facilitating stone passage in patients with ureteral stones.
- A systematic review and meta-analysis 2 found a 19% improvement in stone clearance with tamsulosin, while another study 3 reported a higher stone expulsion rate and shorter expulsion time with tamsulosin.
- However, a randomized clinical trial 6 found no significant difference in stone passage rates between tamsulosin and placebo groups, suggesting that tamsulosin may not be effective for smaller stones (< 9 mm).
Stone Size and Treatment Efficacy
- Subgroup analyses 3, 4, 5 suggest that alpha-blockers may be more effective for larger stones (5-10 mm) than for smaller stones (< 5 mm).
- A study 4 found that tamsulosin significantly improved stone passage in patients with larger stones, while another study 5 reported that alpha-blockers may be less effective for smaller stones.