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Phenazopyridine Can Sub For Dye in Patency Test


 

OTTAWA — The topical urinary tract analgesic phenazopyridine is a good marker for confirming ureteric patency, based on experience in 124 women at one center.

By staining the urine orange or red, a dose of phenazopyridine makes it easy to see urine leak from the ureter and is a good alternative to the standard color marker for urine, indigo carmine, Jane Hui said at the annual clinical meeting of the Society of Obstetricians and Gynaecologists of Canada.

“Phenazopyridine is easy to use, effective, safe, and inexpensive. Phenazopyridine is the agent of choice,” said Ms. Hui, a researcher in the department of ob.gyn. at Queens University in Kingston, Ont. It is now used routinely before urogynecologic surgery at Kingston General Hospital.

Physicians at Kingston General were forced to find a new way to assess ureteric patency and bladder mucosal integrity for women undergoing urogynecologic surgery when indigo carmine became temporarily unavailable in Canada in 2004. Phenazopyridine is an oral drug that has been marketed for many years as an analgesic for patients with urinary tract infection. It has a long history of safety when used short term at the recommended dose of 200 mg. It appears in the urine within about an hour after oral dosing and turns the urine a distinctive color. The drug is sold in the United States as a generic, over-the-counter agent.

Ms. Hui and her associates reviewed case records for 124 women who were treated with phenazopyridine as a urine marker during 127 surgeries performed at Kingston General Hospital from July 2004 to June 2005. All patients were scheduled to receive either 100 or 200 mg of phenazopyridine, although this treatment could be objectively confirmed in only 32 cases.

In all 32 cases, the records confirmed successful determination of bilateral ureteric patency and bladder mucosal integrity during cystoscopy. The treatment was also well tolerated by all patients, and there were no anaphylactic reactions. It was unlikely that any postoperative complications were caused by phenazopyridine use.

A major advantage of phenazopyridine is its cost. In Canada, a 200-mg dose costs $0.29 compared with a $34.50 for a single dose of indigo carmine, which is now again available to Canadian physicians.

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