Monograph: |
PHENAZOPYRIDINE HCL
Description, Mechanism of Action, Pharmacokinetics
Description: Phenazopyridine is an oral urinary tract analgesic. It is used for the symptomatic relief of pain, burning, urgency, frequency, and other discomforts resulting from irritation of the lower urinary tract mucosa. Phenazopyridine is an azo dye that is excreted in the urine; thus, the urine is colored orange or red during use. Rare cases of methemoglobinemia and hemolytic anemia have been reported with use of phenazopyridine, usually following an overdose. Phenazopyridine should not be used for more than 2 days when given concomitantly with an antibacterial agent to treat a urinary tract infection.
Mechanism of Action: The mechanism of action of phenazopyridine has not been fully determined. Phenazopyridine is excreted in the urine and exerts a topical analgesic or local anesthetic effect on the mucosa of the urinary tract. It possesses no antibacterial actions.
Pharmacokinetics: Phenazopyridine is administered orally. The pharmacokinetic disposition of phenazopyridine has not been fully established. Trace amounts of the drug are believed to cross the placenta and to enter the CSF. Metabolism of phenazopyridine probably occurs in the liver; one of the metabolites is acetaminophen. The drug is rapidly excreted by the kidneys, with as much as 65% of an oral dose excreted unchanged in the urine.
Indications
• dysuria
• urinary urgency
Dosage
For the symptomatic relief of dysuria, urinary urgency, and other discomforts arising from irritation of the lower urinary tract mucosa caused by trauma, surgery, endoscopic procedures, or the passage of sounds or catheters:
Oral dosage:
Adults: 200 mg PO three times per day. Administration of phenazopyridine should not exceed 2 days when used concomitantly with an antibacterial agent to treat a urinary tract infection.
Children†: 4 mg/kg PO three times per day. Administration of phenazopyridine should not exceed 2 days when used concomitantly with an antibacterial agent to treat a urinary tract infection.
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