What is the dose of alpha blockers (alpha-adrenergic blockers) for the treatment of nephrolithiasis (kidney stones)?

From the Guidelines

Alpha blockers, such as tamsulosin, should be prescribed at a dose of 0.4 mg daily to facilitate kidney stone passage, as this dose has been shown to be effective in relaxing ureteral smooth muscles and improving stone passage rates 1. The use of alpha blockers for kidney stones is supported by evidence from a meta-analysis, which demonstrated that alpha blocker therapy resulted in a statistically significant 29% increase in stone passage rates compared to control patients 1.

Key Points to Consider

• The recommended dose of tamsulosin is 0.4 mg taken once daily, preferably after the same meal each day.
• Alternative alpha blockers include alfuzosin at 10 mg daily, doxazosin at 4 mg daily, or terazosin at 5-10 mg daily.
• Treatment usually continues for 2-4 weeks or until the stone passes.
• These medications work by relaxing the smooth muscles in the ureter, which helps widen the passage and allows the stone to move more easily through the urinary tract.
• Common side effects include dizziness, headache, and retrograde ejaculation in men.
• Patients should be advised to stay well-hydrated by drinking 2-3 liters of water daily while taking alpha blockers.
• These medications are most effective for stones less than 10 mm in size located in the distal ureter.
• If severe pain, fever, or inability to urinate develops while taking alpha blockers, immediate medical attention should be sought as these may indicate complications requiring urgent intervention.

Additional Considerations

• The choice of alpha blocker may depend on the patient's individual needs and medical history, as well as the potential for side effects 1.
• It is essential to monitor patients for adverse events, such as orthostatic hypotension, dizziness, and ejaculatory dysfunction, and to adjust the treatment plan as needed.

From the Research

Dose of Alpha Blockers for Kidney Stones

• The dose of alpha blockers, specifically tamsulosin, used in the treatment of kidney stones is typically 0.4 mg/day 2, 3, 4, 5.
• This dose has been shown to be effective in improving stone clearance rates after extracorporeal shock wave lithotripsy (ESWL) 2, 4, 5.
• The use of alpha blockers, such as tamsulosin, has been found to be beneficial in patients with ureteral stones ≤10 mm treated without lithotripsy, and in patients with renal or ureteral stones >10 mm treated with lithotripsy 3.
• The estimated number needed to treat to achieve a single patient with renal stone-free status after eight weeks of ESWL adjuvant treatment with tamsulosin was 19 2.
• Adverse events were more frequent in the nifedipine than in the placebo group, but without a significant difference between the nifedipine and tamsulosin or the tamsulosin and placebo groups 4.

Stone Size and Alpha Blocker Efficacy

• Alpha blockers have been found to be more effective for stones 10-20 mm in size, while there was no difference for stones <10 mm 3, 4.
• The stone-free rates after ESWL with adjuvant tamsulosin or nifedipine were significantly increased only for nonlower pole renal stones 10-20 mm in size compared with placebo 4.
• Tamsulosin has been found to facilitate earlier clearance of fragments after ESWL, with a statistically significant difference in time of stone passage from onset of treatment in the tamsulosin group compared to the control group 5.