Differential Effect of Silodosin Versus Tamsulosin on Stone Clearance After Extra-corporeal Shock Wave Lithotripsy

Tamsulosin is an alpha blocker usually prescribed for urinary complaints that has been shown
to have some benefit in allowing kidney stones to pass through the ureter. Silodosin is a
new alpha blocker that acts more rapidly than tamsulosin and has been shown to have specific
receptors on the ureter. The investigators would like to see if there is some benefit to
taking silodosin over tamsulosin after extra-corporeal shock wave lithotripsy (ESWL) to
break kidney stones in terms of allowing the ureteral fragments to pass through the ureter.
Our hypothesis is that silodosin will be at least as effective as tamsulosin in terms of
allowing stones to pass, but may allow them to pass more quickly because of the rapid onset
of action.

The side effect profile for both drugs is quite similar and tolerable. Patients may
experience some common side effects associated with tamsulosin, including abnormal
ejaculation, dizziness, rhinitis (runny nose, sneezing), and somnolence (sleepiness).
Serious reactions include orthostatic hypotension, syncope (fainting), and priapism
(prolonged undesired erection).

Patients may experience some common side effects with both silodosin and tamsulosin
including ejaculatory dysfunction, dizziness, postural hypotension, diarrhea, and headache.
Serious side effects are rare and include orthostatic hypotension, intra-operative floppy
iris syndrome, syncope, and priapism.

Patients will experience the discomfort normally associated with kidney stones. All efforts
will be made to alleviate these discomforts, including the use of the study medications.
Patients will be able to take their routine prescribed pain medications, and will be asked
to keep a record of their pain medication use.

The investigators will be randomly enrolling patients from all racial backgrounds and of
both genders. They must have kidney stones ranging in size from 4mm to 1.0 cm and have no
prior treatment for the study.

The primary endpoint of this study is the clearance rate of kidney stones. That is, in what
period of time does the patient achieve clearance, is stone free and has all residual stones
gone. The secondary endpoints of this study include analgesic use, residual stones
remaining, need for re-treatment, need for intervention, steinstrasse clearance, and the
need for hospitalization.