The objectives of the study are to assess the systemic exposure, safety and efficacy of three concentrations of OMS201 in subjects undergoing retrograde ureteroscopic removal of upper urinary tract stones.

The main objective is to estimate the systemic exposure of OMS201 in retrograde ureteroscopic treatment of upper urinary tract stones. Safety will be assessed by vital signs, laboratory values and adverse events. Exploratory efficacy measures will assess the effect of OMS201 on postoperative pain, duration of surgery and ease of placement of a ureteral access sheath.

Inclusion Criteria:

• 18 - 65 years of age.
• Subject is undergoing retrograde ureteroscopic removal of renal-collecting system or ureteral stones for which general anesthesia will be used.

Exclusion Criteria:

• No allergies to any of the individual ingredients in OMS201.
• Subject taking a prohibited medication.
• Pregnant woman, nursing mother, or woman of child-bearing age unwilling to take contraception for the duration of the study.
• Subject who has had a renal transplant, has a single kidney, has compromised renal function, or has evidence of papillary necrosis.
• Subject who has evidence of a clinically significant urinary tract infection.
• Subject who has a prior history of open or laparoscopic urinary tract surgery, or a history of a ureteral stricture.
• Subject who has congenital anomalies that would engender an increased procedural safety risk.
• Subject with a history of clinically significant chronic or episodic hypotension.
• Subject's physical examination is significantly abnormal for purposes of the study as determined by the Investigator.
• Subject's screening laboratory evaluations are not within normal limits AND abnormal results are determined by the Investigator to be clinically significant.
• Subject is at risk from anesthesia.
• Subject is on chronic diuretic use.
• Subject has a present condition or history of any clinically significant medical disorder and is determined by the Investigator to be an unsuitable candidate for receipt of an investigational drug.