Usage patterns of over-the-counter phenazopyridine (pyridium)

Little is known about how the public uses formerly prescription medications that are available over-the-counter (OTC). This study examines whether consumers inappropriately use and substitute a recently widely distributed OTC urinary analgesic, phenazopyridine, for provider care.

We conducted a cross-sectional survey of a stratified cluster random sample of OTC phenazopyridine purchasers (N = 434) in 31 Los Angeles retail pharmacies over 5 months. Recruited by shelf advertisements, participants were 18 years or older who purchased a phenazopyridine product. Each completed a 25-item self-administered anonymous questionnaire. Inappropriate use was defined as 1) having medical contraindications to phenazopyridine, or 2) not having concurrent antibiotic and/or provider evaluation for the urinary symptoms.

The survey response rate was 58%. Fifty-one percent of the respondents used OTC phenazopyridine inappropriately, and 38% substituted it for medical care. Multiple logistic regression analyses revealed that inappropriate use was correlated with having little time to see a provider (odds ratio [OR], 1.57; 95% confidence interval [95% CI], 1.26 to 1.96), receiving friend's or family's advice (OR, 1.25; 95% CI, 1.05 to 1.47), having prior urinary tract infections (OR, 0.49; 95% CI, 0.30 to 0.80), having used prescription phenazopyridine, (OR, 0.40; 95% CI, 0.25 to 0.63), and having back pain (OR, 0.34; 95% CI, 0.16 to 0.74). Similar correlates were found in those who substituted OTC phenazopyridine for provider care. Respondents with incorrect knowledge about phenazopyridine's mode of action had 1.9 times greater odds of inappropriate use and 2.2 times greater odds of substitution than those who had correct knowledge about this drug.

Inappropriate use of OTC phenazopyridine appears common. Increasing the public's knowledge about reclassified drugs may help to mitigate this problem.