Calcium channel blockers have also been investigated for MET. Ureteral smooth muscle contraction is mediated by calcium channels and therefore drugs such as nifedipine theoretically should decrease ureteral spasm and improve stone passage.

 


Continue Reading

As mentioned previously, Dellabella et al showed an 80% stone passage rate in patients taking nifedipine, as compared to 43% of control patients.7 The meta-analysis by the AUA/EAU Ureteral Stone Guidelines panel showed an overall improvement in stone expulsion of only 9%, which was not statistically significant.4

The panel suggests advising appropriate patients with stones less than 10 mm in size of the availability of MET as well as the side effects, and that MET is an “off label” use of these medications. Patients should be followed closely with periodic imaging and “should have well-controlled pain, no clinical evidence of sepsis, and adequate renal functional reserve.” Surgical intervention would be indicated if obstruction persists, the stone fails to progress towards passage, or in the setting of worsening pain.4 

 

The advantages of MET are clear and not strictly limited to improved stone passage rates. This modality may decrease patient exposure to the morbidities and complications of both ureteroscopy and shock wave lithotripsy. Ongoing studies are looking at the likely potential economic benefits of MET in decreasing health care expenditures as well as lost work days of patients suffering from nephrolithiasis.

 

Still, not all urologists seem to have hopped on this bandwagon. We performed a regional survey of urologists showing that only 32% of respondents would use MET to manage distal ureteral stones less than 5 mm in size, despite literature suggesting otherwise.10 

 

In 2005, Chang and Campbell identified a link between tamsulosin and billowing and prolapse of the iris during cataract surgery termed “intra-operative floppy iris syndrome.”11 Current recommendations are to advise tamsulosin patients to stop taking the drug prior to cataract surgery.12 

 

In spite of this, medical expulsive therapy is a effective off-label treatment option for many stone patients.  Further studies will help define the cost, side effects, and range of utility of MET, but in the meantime it appears to be here to stay.

 

Sara L. Best, MD, is a senior resident in urology and Stephen Y. Nakada, MD, is professor and chairman of urology at the University of Wisconsin School of Medicine and Public Health in Madison.

References

  1. Ibrahim AI, Shetty SD, Awad RM, Patel KP. Prognostic factors in the conservative treatment of ureteric stones. Br J Urol. 1991;67:358-361.
  2. Peters HJ, Eckstein W. Possible pharmacological means of treating renal colic. Urol Res. 1975;3:55-59.
  3. Nakada SY, Hedican SP, Moon TD, et al. Doxazosin relaxes ureteral smooth muscle and reverses epinephrine-induced ureteral contractility. J Urol. suppl.2005. 173:299, abstract 104.
  4. Preminger GM, Tiselius HG, Assimos DG, et al. EAU/AUA Nephrolithiasis Guideline Panel. 2007 guideline for the management of ureteral calculi. J Urol. 2007;178:2418-2434.
  5. Yilmaz E, Batislam E, Basar MM, et al. The comparison and efficacy of 3 different alpha1-adrenergic blockers for distal ureteral stones. J Urol. 2005;173:2010-2012.
  6. Porpiglia F, Ghignone G, Fiori C, et al. Nifedipine versus tamsulosin for the management of lower ureteral stones. J Urol. 2004;172:568-571.
  7. Dellabella M, Milanese G, Muzzonigro G. Efficacy of tamsulosin in the medical management of juxtavesical ureteral stones. J Urol. 2003;170:2202-2205.
  8. Hollingsworth JM, Rogers MA, Kaufman SR, et al. Medical therapy to facilitate urinary stone passage: a meta-analysis. Lancet. 2006;368:1171-1179.
  9. Dellabella M, Milanese G, Muzzonigro G. Randomized trial of the efficacy of tamsulosin, nifedipine and phloroglucinol in medical expulsive therapy for distal ureteral calculi. J Urol. 2005;174:167-172.
  10. Bandi G, Best SL, Nakada SY. Current practice patterns in management of upper urinary tract calculi in the north-central United States. J Endo. In press.
  11. Chang DF, Campbell JR. Intraoperative floppy iris syndrome associated with tamsulosin. J Cataract Refract Surg. 2005;31:664-673.
  12. Chang DF, Osher RH, Wang L, Koch DD. Prospective multicenter evaluation of cataract surgery in patients taking tamsulosin (Flomax). Ophthalmology. 2007;114:957-964.