Phenazopyridine - Pharmacokinetics

Pharmacokinetics

The drug is administered as a tablet, in either 100 mg or 200 mg doses of phenazopyridine hydrochloride. The tablets have a light red, dark red or dark violet color, and are taken with food.

The full pharmacokinetic properties of phenazopyridine have not been determined. It has mostly been studied in animal models, but they may not be very representative of humans. Rat models have shown its half-life to be 7.35 hours, and that it is excreted 40% hepatically.

Its mode of action is not well known, and only basic information on its interaction with the body is available. It is known that the chemical has a direct topical analgesic effect on the mucosa lining of the urinary tract. It is rapidly excreted by the kidneys directly into the urine. Hydroxylation is the major form of metabolism in humans, and the azo bond is usually not cleaved. On the order of 65% of an oral dose will be excreted directly into the urine chemically unchanged.