Phenazopyridine
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Phenazopyridine
Pyridium (Rx), Azo Standard, AZO Urinary Pain Relief (OTC)
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Summary
Classes
Common uses
Symptomatic relief of urinary urgency, frequency, dysuria, and burning0, adjunctive only (does not treat the underlying infection)
Pharmacy
Starting dose
100-200 mg PO TID after meals × no more than 2 days when used with concurrent antibiotic
Preparations
95 mg (OTC), 99.5 mg, 100 mg, 200 mg tablets
US FDA Max
Limit to 48 hours of use to avoid hemolysis and methemoglobinemia
Pharmacology
Routes
Oral
Onset
Symptom relief within 30 minutes
Duration
6-8 hours
Half-life
~7-10 hours (variable; longer in renal impairment)[1]
Bioavailability
High (oral)[1]
Pregnancy
Limited data; not first-line in pregnancy.[citation needed]
Legal status
OTC (lower doses) and Rx-only (higher doses) in US
Purported mechanism
Phenazopyridine is an azo dye with topical analgesic action on the urinary tract mucosa; the precise mechanism is not fully characterized but appears to involve local membrane effects on bladder and urethral sensory nerves.0 Produces characteristic bright orange-red discoloration of urine, sweat, tears, and contact lenses; G6PD-deficient patients are at increased risk of hemolytic anemia. Chronic high-dose use is associated with methemoglobinemia and renal/hepatic toxicity; treatment limit of 2 days is the practical safety margin[1].
References
- ↑ 1.0 1.1 1.2 FDA Prescribing Information, phenazopyridine, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/008676s050lbl.pdf