Phenazopyridine and phenazopyridine hydrochloride.
Explore the source record for details and available documents.
Aminopyridines↗
SEARCH · Search PubMed
Results for “Phenazopyridine”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Usage patterns of over-the-counter phenazopyridine (pyridium).
OBJECTIVES: 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. DESIGN/SETTING: 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. RESULTS: 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. CONCLUSION: Inappropriate use of OTC phenazopyridine appears common. Increasing the public's knowledge about reclassified drugs may help to mitigate this problem.
Adult↗
Determination of phenazopyridine in human plasma via LC-MS and subsequent development of a pharmacokinetic model.
This paper describes a new LC-MS method for the determination of phenazopyridine and the subsequent development of a pharmacokinetic model for phenazopyridine in vivo. Phenazopyridine hydrochloride is a strong analgesic used in the treatment of urinary tract infections. Although it has been used as a clinical treatment for a very long time, pharmacokinetic data and suitable methods for its determination in plasma are currently lacking. The study described in this paper used high performance liquid chromatography-mass spectrometry, HPLC-MS, to determine the plasma concentrations of phenazopyridine in human subjects after oral administration. After liquid-liquid extraction, the phenazopyridine in the plasma was analyzed on a C18 column under SIM mode. A double-peak phenomenon was observed in most of the concentration-time profiles of the subjects. Although some drugs are known to cause this phenomenon, phenazopyridine has not been reported to do so. Several possible causes were analyzed in order to obtain an explanation. We proposed a two-site absorption compartment model to fit the concentration data in vivo, which has one more absorption site than the classical one-compartment model. The model describes the concentration profiles in different dose groups well and could provide an explanation for the double-peak phenomenon. The three dose groups exhibited similar model parameters and a linear pharmacokinetic process over the dose range used.
Area Under Curve↗
Phenazopyridine toxicosis in the cat.
Severe illness developed after the oral administration of several drugs, including large doses of phenazopyridine (100 mg TID for 4 days) to a cat with dysuria and hematuria. Hemolysis and icterus were evident in blood serum and plasma after day 4 of drug administration, and many hemolyzed red blood cell "ghosts" containing Heinz bodies were observed on a stained blood smear. The cat became anemic and died within 48 hours after the last dose was administered. In an attempt to confirm a cause-and-effect relationship between drug administration and disease, 100 mg of phenazopyridine was given TID (65 mg/kg/day) for 3 days to a clinically normal cat. Nearly 50% of the hemoglobin was oxidized to methemoglobin during the course of phenazopyridine administration. Lower dosages of phenazopyridine (10 and 20 mg/kg/day) for longer periods of administration to 2 other clinically normal cats did not result in illness or anemia; however, the number and size of Heinz bodies and blood methemoglobin content were increased. Evidence of hepatic injury was observed in the clinically affected cat and in 2 of the experimental cats. The relationship between hepatic injury and toxic signs was not determined. Combination products recommeneded for treatment of cystitis in man often contain phenazopyridine. Such products should be avoided in cats unless a safe, effective dosage for phenazopyridine can be established.
Anemia, Hemolytic↗
Urinary tract disorders. Clinical comparison of flavoxate and phenazopyridine.
In nine separate clinical trials, 382 patients having symptoms of either prostatitis, acute cystitis, urethritis, and/or trigonitis were randomly assigned to treatment with flavoxate or phenazopyridine. Over-all response was evaluated in 384 patients after five days of therapy. In patients having prostatitis, response was satisfactory in 66 per cent treated with flavoxate and 31 per cent treated with phenazopyridine. In all other patients, satisfactory responses were reported in 80 per cent on flavoxate compared with 56 per cent on phenazopyridine. Similarly, symptom-severity evaluations at two and five days of therapy showed most symptoms improved in more of the patients on flavoxate therapy than on phenazopyridine therapy. Although more adverse effects were reported in patients treated with phenazopyridine than with flavoxate, the difference between medications was not statistically significant.
Acute Disease↗
Evaluation of phenazopyridine hydrochloride as a tool in the diagnosis of premature rupture of the membranes.
This is a prospective study to determine whether a maternal orally administered azo dye, phenazopyridine hydrochloride, would cross into amniotic fluid, and thus be of potential aid in the diagnosis of rupture of the membranes. Based on anecdotal experience, we hypothesized that this compound would cross the placenta and be excreted in the fetal urine, causing discoloration of the amniotic fluid. Ten patients with uncomplicated pregnancies undergoing elective amniocentesis for obstetric indications received an oral dose of 400 mg of phenazopyridine hydrochloride 4 hours prior to the procedure. Amniotic fluid was also available from five control patients who did not receive phenazopyridine hydrochloride. The typical orange-to-red discoloration of the urine was seen in all study patients, indicating ingestion of the dye. None of the ten patients had evidence of the azo dye in their amniotic fluid by visual inspection or by spectrophotometric absorbance. After the amniotic fluid samples were acidified, the presence of the azo dye was visually demonstrable, and spectrophotometry confirmed measurable concentrations (mean +/- SE: 13.08 +/- 0.72 micrograms/ml). We conclude that although phenazopyridine hydrochloride does cross the placenta into the fetal compartment, its presence causes a visual and spectrophotometric change in the color of amniotic fluid only when the normal basic pH of amniotic fluid is acidified.
Amniotic Fluid↗
Acquired methemoglobinemia and hemolytic anemia after usual doses of phenazopyridine.
Two patients developed symptomatic methemoglobinemia and hemolytic anemia after treatment with phenazopyridine. Methemoglobinemia appears to be a rare occurrence after commonly used doses of phenazopyridine; phenazopyridine-associated hemolytic anemia has been reported both after overdose and after usual doses. The presentation of methemoglobinemia in the first patient and the response to treatment with methylene blue in the second patient were unusual, suggesting that the patients had a red cell defect or were exposed to other oxidizing substances. One of the major metabolites of phenazopyridine is aniline, a known cause of methemoglobinemia. Aniline-induced methemoglobinemia is less responsive to treatment with methylene blue than nitrate- or nitrite-induced methemoglobinemia. This may explain, in part, the poor response to methylene blue by one of our patients.
Aged↗
Ciprofloxacin bioavailability is enhanced by oral co-administration with phenazopyridine: a pharmacokinetic study in a Mexican population.
BACKGROUND: and objective: In Mexico, urinary tract infections (UTIs) constitute the second most frequent type of infections treated at primary-care clinics. Ciprofloxacin has played a major role in the treatment of UTIs because it has a broad spectrum of antibacterial activity. In addition to antimicrobial agents, phenazopyridine has been used to alleviate symptoms that occur during episodes of UTI. Thus, the present study was designed to compare the pharmacokinetic behaviour of ciprofloxacin administered alone versus ciprofloxacin combined with phenazopyridine. PATIENTS AND METHODS: Twenty-four healthy male Mexican volunteers participated in this project. The study was carried out with a single oral dose of ciprofloxacin 500mg. The double-blind, crossover, randomised, balanced trial design comprised two treatments, two periods and two sequences. After administration of the study medication, serial blood samples were collected for a period of 12 hours. The harvested plasma was analysed for ciprofloxacin by high-performance liquid chromatography. The area under the concentration-time curve to last measurable concentration (AUC(t)), area under the concentration-time curve extrapolated to infinity (AUC(infinity)), peak plasma concentration (C(max)), time to reach C(max) (t(max)), mean residence time (MRT), elimination constant (k(e)) and elimination half-life (t(1/2)) were determined from plasma concentrations of both treatments and considered as primary variables for statistical analysis. RESULTS: While there were no differences between the two treatments in terms of C(max) and k(e), AUC(t )and AUC(infinity) were 35% and 29% higher, respectively, in the combined treatment arm. Moreover, a significant delay in t(max )(from 1 to 1.5 hours) and a statistical increase of 29% in MRT were also observed with phenazopyridine co-administration. CONCLUSION: Oral co-administration of phenazopyridine increases ciprofloxacin bioavailability with regard to the amount absorbed (AUC) and permanence in the body (MRT), which could be useful during treatment.
Administration, Oral↗
Bioassay of phenazopyridine hydrochloride for possible carcinogenicity.
A bioassay of phenazopyridine hydrochloride for possible carcinogenicity was conducted by administering the test chemical in feed to Fischer 344 rats and B6C3F1 mice. Groups of 35 rats and 35 mice of each sex were administered phenazopyridine hydrochloride at one of the following doses, either 3,700 or 7,500 ppm for rats and either 600 or 1,200 ppm for mice. The rats were administered the chemical for 78 weeks, then observed for 26 or 27 additional weeks; the mice were administered the chemical for 80 weeks, then observed for 25-27 additional weeks. Matched controls consisted of 15 untreated rats and 15 untreated mice of each sex. All surviving rats were killed at 104 or 105 weeks, all surviving mice at 105-107 weeks. Mean body weights of the dosed rats and mice of each sex were consistently lower than those of corresponding control animals, and the depressions in mean body weight were dose related. Mortality in the groups of rats and mice did not, however, show dose-related trends, and sufficient numbers of animals of both dosed and control groups were at risk for the development of late-appearing tumors. In male rats, adenomas or adenocarcinomas of the large intestine (colon or rectum) occurred at incidences having a significant dose-related trend (P=0.015). The direct comparison of the incidences in each of the dosed groups with that in the control group was not significant (controls 0/14, low-dose 4/34, high-dose 8/35). In the females, 3/33 low-dose and 5/32 high-dose animals, but no control animals, had this tumor. In addition, sarcomas were observed in the colon of one low-dose male and one high-dose female. The laboratory historical records showed no incidence of adenomas or adenocarcinomas of the large intestine in 260 females and only one adenomatous polyp in 260 males. Assuming a spontaneous incidence of 1/261 (0.038%) and a binomial distribution of such tumors, the occurrence seen in the male and female high-dose groups are both significantly (P<0.001) different from the expected value. Thus, these tumors are considered to be related to administration of the test chemical. In female mice, the combined incidence of hepatocellular adenomas and carcinomas showed a significant dose-related trend (P=0.002), and the incidence in the high-dose group was significant (P=0.003) when compared with that in the control group (controls 2/15, low-dose 11/34, high-dose 19/32). The incidence of hepatocellular carcinomas, considered alone, also was significant in female mice, showing a dose-related trend (P=0.010) and a P value of 0.039 for the comparison of the high-dose group with the control group. In the males, the combined incidence of hepatocellular adenomas and carcinomas was not significant. It is concluded that under the conditions of this bioassay, phenazopyridine hydrochloride was carcinogenic in Fischer 344 rats, inducing adenocarcinomas of the colon in both males and females. Although phenazopyridine hydrochloride was not carcinogenic in male B6C3F1 mice, the chemical was carcinogenic in females, inducing hepatocellular adenomas and carcinomas.
Journal Article↗
1H, 13C and 15N NMR assignments of phenazopyridine derivatives.
Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional (1)H, (13)C and (15)N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the (15)N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry.
Carbon Isotopes↗
Phenazopyridine in the management of autonomic dysreflexia associated with urinary tract infection.
OBJECTIVE: Documentation of possible usefulness of phenazopyridine in the management of autonomic dysreflexia (AD) associated with urinary tract infection. SETTING: Veterans Administration Spinal Cord Injury Center. RESULTS: A 36-year-old man with tetraplegia and AD triggered by cystitis improved both subjectively and objectively following the institution of a 2-day course of phenazopyridine. CONCLUSION: Phenazopyridine may be useful in the management of AD associated with cystitis.
Administration, Oral↗
Phenazopyridine-induced sulfhemoglobinemia.
OBJECTIVE: To report a case of sulfhemoglobinemia in a patient receiving phenazopyridine for a urinary tract infection. CASE SUMMARY: A 63-year-old white woman presented to the emergency department with complaints of fatigue and bluish discoloration of her body that had gradually progressed over the previous 6-8 weeks. About 4 months prior to presenting to the emergency department, she had started taking phenazopyridine, an over-the-counter medication for symptoms of dysuria. Because the cyanosis did not improve after the patient received oxygen and methylene blue, sulfhemoglobinemia was suspected and confirmed by spectrophotometer analysis. DISCUSSION: Sulfhemoglobin is a green-pigmented molecule containing a sulfur atom in one or more of the porphyrin rings. It is a rare cause of cyanosis, which is usually drug induced. Sulfhemoglobinemia is suspected when a cyanotic patient has normal to near-normal oxygen tension, laboratory reports of elevated methemoglobin, and does not respond to methylene blue therapy. Sulfhemoglobinemia is relatively rare, despite the widespread use of drugs that have been reported to cause it. Predisposing factors, such as chronic constipation, present in our patient, have been suggested as a source of hydrogen sulfide. CONCLUSIONS: This case of sulfhemoglobinemia, which occurred after the patient took phenazopyridine, is considered a probable adverse event according to the Naranjo probability scale.
Administration, Oral↗
Consumer knowledge of over-the-counter phenazopyridine.
BACKGROUND: Effective use of over-the-counter (OTC) medications depends on purchasers' knowledge of their indications. This study examines consumer knowledge regarding the urinary tract analgesic phenazopyridine, which recently became available without prescription. METHOD: We conducted a cross-sectional survey of a stratified cluster random sample of purchasers of OTC phenazopyridine (N = 434) in 31 Los Angeles retail pharmacies. RESULTS: The response rate was 58%. Only 42% correctly characterized the likely cause of their symptoms, and only 57% correctly characterized the action of the drug. Worse consumer knowledge was associated with nonwhite race, first-time use, and less contact with health providers. CONCLUSION: Many consumers possess poor knowledge about phenazopyridine, potentially leading to undertreatment, especially in groups with worse access to care.
Anesthetics, Local↗
Application of stochastic resonance to quantitative analysis of weak chromatographic signal of phenazopyridine in human plasma.
AIM: To apply stochastic resonance algorithm (SRA) to quantitative analysis of weak chromatographic signal, which was embedded in the noise. METHODS: Based on the theory of stochastic resonance (SR), a simple and effective SRA has been established to improve analytical detection limits of chromatographic analysis, which apply to enhance the signal to noise ratio by the optimization of the parameters and Runge-Kutta method, was established. The method was used to quantitative analysis of phenazopyridine in human plasma by HPLC/UV. Meanwhile this method is compared with HPLC/MS. RESULTS: By experimental chromatographic data sets, an excellent quantitative relationship between concentrations of phenazopyridine and their responses had been obtained. The concentration of phenazopyridine in plasma determined by HPLC/UV with SRA and HPLC/MS showed that there was no significant difference (P > 0.05) between the two methods. CONCLUSION: The new method was feasible.
Chromatography, High Pressure Liquid↗
Amperometric determination of phenazopyridine hydrochloride in a flowing stream at the glassy carbon electrode.
A flow-injection method is described for the determination of phenazopyridine hydrochloride, based on electrochemical oxidation at the glassy carbon electrode. The suggested method is highly specific and can be used to determine phenazopyridine HCl in the presence of most drugs commonly found in pharmaceutical dosage forms or administered therapeutically. Applying a constant potential of +950 mV vs Ag/AgCl/3.5M KCl reference electrode, the calibration curve was linear in the 1-30 micrograms/mL range, with minimum detectability of 0.2 ng (signal-to-noise ratio 2). Good accuracy and precision were obtained when the method was applied to some dosage forms containing phenazopyridine HCl. Although automation was not used in this study, an automated system could be incorporated because the method uses the technique of continuous analysis in a flowing stream.
Aminopyridines↗
2,3,6-triaminopyridine, a metabolite of the urinary tract analgesic phenazopyridine, causes muscle necrosis and renal damage in rats.
Some aromatic polyamines form very stable free radicals and readily undergo autoxidation with concomitant formation of 'active oxygen' species. These substances cause necrosis of striated muscle in rats, and it has been suggested that this is due to free radical formation and disruption of energy production through their oxidation via the cytochrome c/cytochrome oxidase system of mitochondria. 2,3,6-Triaminopyridine, which is structurally related to the myotoxic amines and likewise undergoes autoxidation and disrupts mitochondrial metabolism, is a metabolite of the widely used urinary analgesic phenazopyridine. When administered to rats, triaminopyridine caused extensive necrosis of skeletal muscle and a lesser degree of damage to heart muscle. It also induced vacuolation and necrosis of distal tubules of the kidney, associated with tubular dilatation and cast formation. Both muscle damage and renal tubular necrosis have been reported following use or abuse of phenazopyridine, and it is likely that triaminopyridine is responsible for both of these effects.
Anesthetics, Local↗
Protracted methemoglobinemia after phenazopyridine overdose in an infant.
Acquired methemoglobinemia may be produced by the ingestion or absorption of certain chemicals and xenobiotics. A case of methemoglobinemia in an 8.5-month old infant who ingested approximately 227 mg/kg of phenazopyridine is presented. Although this adverse event is often reversed with a single dose of methylene blue, this patient required three doses of methylene blue (1 mg/kg) over a 25-hour period. It is suggested that the need for repeated doses of methylene blue in this case was not only related to the large dose of phenazopyridine, but also its metabolites (i.e., aniline), which have the potential to produce methemoglobinemia. This case illustrates the need for close observation and serial monitoring of methemoglobin levels in patients who are at increased risk for the development of protracted methemoglobinemia. Integration of knowledge of developmental pharmacology, drug metabolism, and pharmacodynamic properties are critical determinants in the evaluation and treatment of patients with drug-induced methemoglobinemia.
Adolescent↗
Rapid increase in calculous size: a possible hazard of phenazopyridine hydrochloride therapy in the presence of already formed stones.
Phenazopyridine hydrochloride is an effective oral urinary analgesic commonly used for the treatment of irritative lower urinary tract conditions. We believe that stones already present may serve as a nidus for significant deposition of phenazopyridine hydrochloride.
Humans↗