Phenazopyridine

Reproductive studies with phenazopyridine (in combination with sulfacytine) in rats given up to 110 mg/kg/day and in rabbits given up to 39 mg/kg/day during organogenesis revealed no evidence of harm to offspring.

One very limited prospective study in humans demonstrated that phenazopyridine traverses the placenta into the fetal compartment. There are no adequate and well-controlled studies in pregnant women. Therefore, phenazopyridine should be used in pregnant women only if the benefit clearly outweighs the risk.

It is unknown if the drug is excreted in human milk. Because many drugs are excreted in human milk, precaution should be exercised.

Long-term administration of phenazopyridine has been associated with tumors of the large intestine in rats and of the liver in mice. Available epidemiological data are insufficient to evaluate the carcinogenicity of phenazopyridine in humans. In vitro studies indicate that phenazopyridine in the presence of metabolic activation is mutagenic in bacteria and mutagenic and clastogenic in mammalian cells.

Adverse Drug Reaction Overview

Gastrointestinal: nausea, vomiting and diarrhea.

Nervous System: headache, aseptic meningitis.

Integumentary: rash, pruritus, discoloration, jaundice.

Renal: renal toxicity usually associated with overdose, renal calculi.

Hematologic: methemoglobinemia, hemolytic anemia, potential hemolytic agent in G-6-PD deficiency, sulfhemoglobinemia, neutropenia, leukopenia, pancytopenia.

Body as a Whole: anaphylactoid-like reaction and hypersensitivity hepatitis.

Special Senses: visual disturbances, eye irritation, ear pain, reversible loss of color vision.

Other: hepatic toxicity usually associated with overdose, discoloration of body fluids.