There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
The FDA Drug Labels for tamsulosin (PO) do not address this question.
From the Research
Effectiveness of Flomax (Tamsulosin) for Treating 4mm Ureteral Stones
- The effectiveness of Flomax (Tamsulosin) for treating 4mm ureteral stones is a topic of ongoing research and debate 1, 2, 3.
- Studies have shown that Tamsulosin may be effective in facilitating stone passage for larger stones (5-10 mm), but its effectiveness for smaller stones (<4-5 mm) is less clear 2, 3.
- A systematic review and meta-analysis of randomized controlled trials found that Tamsulosin was associated with a higher stone expulsion rate and shorter stone expulsion time for stones greater than 5 mm, but not for stones 5 mm or less 3.
- Another study found that Tamsulosin did not significantly improve stone passage in patients with smaller stones (<4-5 mm) 2.
- However, a prospective randomized study in children with distal ureteric calculi <12 mm found that Tamsulosin was effective in facilitating ureteral stone expulsion, with a stone-free rate of 87.8% in the treatment group compared to 64.2% in the placebo group 4.
Stone Size and Treatment Outcome
- The size of the ureteral stone appears to be an important factor in determining the effectiveness of Tamsulosin treatment 2, 3.
- Studies have shown that Tamsulosin is more effective for larger stones (5-10 mm) than for smaller stones (<4-5 mm) 2, 3.
- However, more research is needed to fully understand the relationship between stone size and treatment outcome with Tamsulosin.
Safety and Efficacy
- Tamsulosin has been shown to be relatively safe and well-tolerated in patients with ureteral stones, with no significant difference in side effects compared to a control group 3.
- The use of Tamsulosin as a medical expulsive therapy for ureteral stones has been suggested to be effective and relatively safe, particularly for patients with stones greater than 5 mm 3.