Physiologic Effect of Nifedipine and Tamsulosin on Contractility of Distal Ureter

Abstract

We believe that both tamsulosin and nifedipine prevent the disorganized antiperistalsis associated with ureteral spasm while allowing some degree of antegrade fluid-bolus (stone) propagation. It is this mechanism of action that facilitates spontaneous passage and reduces associated renal colic when tamsulosin and nifedipine are used for the management of ureteral stone disease.

Myth: Nephrolithiasis and medical expulsive therapy

“…No correlation was found between stone size and expulsion time for patients in the treatment group. 5 This study 5 and others 7,9 suggest that calcium channel blockers can facilitate spontaneous passage for stones up to 10 mm, contrary to information provided in emergency medicine textbooks.…”

“…2,3 Recent research shows that medical expulsive therapy in the ED can increase the expulsion rate and decrease the expulsion time thereby reducing lost workdays, urological visits and (avoidable) stone removal procedures. [3][4][5][6][7][8] Rosen's textbook of emergency medicine suggests that 90% of stones less than 5 mm and 15% of stones between 5 mm and 8 mm will pass spontaneously within 4 weeks, while 95% of those larger than 8 mm will require urological intervention. Recommended management includes analgesics, antibiotics and hydration for stones less than 5 mm or urology referral with consideration of extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy or surgical removal for larger stones.…”

Determine the Effectiveness of Low Dose Tamsulosin as a Medical Expulsive Therapy in Patients with Lower Ureteric Stones

“…Average time to stone passage in the control groups was 4.6-20 days, but only 5-9.3 days and 2.7-7.9 days in those receiving nifedipine and tamsulosin, respectively. The other α 1-adrenoreceptor antagonists, based on one trial, appear to have expulsion rates similar to those of tamsulosin [27].…”

“…Stone size and location are the main factors that can influence their passage; a stone smaller than 4 mm is usually passed after conservative treatment [2]. The human ureter contains a high number of α-adrenergic receptors, especially α1d -receptors at the lower part of the ureter [3,4].…”

Risks associated with drug treatments for kidney stones

“…In the recent SUSPEND trial it was to be no more effective than placebo 109 . Nifedipine reduces contractility of the distal ureter similarly to alphaadrenergic blockers allowing improved stone passage 120 . It is used off-label for medical expulsion therapy.…”