Phenazopyridinum

Phenazopyridinum Uses, Dosage, Side Effects, Food Interaction and all others data.

Phenazopyridinum, also known as Pyridium, is a urinary tract analgesic used for the short-term management of urinary tract irritation and its associated unpleasant symptoms such as burning and pain during urination. In the USA, this drug was previously marked by Roche but has been discontinued by the FDA. It is still used in various parts of the world. Ingestion of phenazopyridine is found to change the appearance of the urine by imparting an orange or red color, as it is considered an azo dye.

Phenazopyridinum acts as a local anesthetic offering relief from irritating conditions of the urinary tract. It relieves urinary urgency frequency, burning, pain, and discomfort.

A note on urine and skin discoloration and interference with test results

Phenazopyridinum
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Phenazopyridinum
Availability	Rx and/or OTC
Generic	Phenazopyridine
Phenazopyridine Other Names	Fenazopiridina, Phenazopyridine, Phénazopyridine, Phenazopyridinum
Related Drugs	oxybutynin, Pyridium, imipramine, Ditropan, Azo Urinary Pain Relief, Elmiron, Ditropan XL, flavoxate, pentosan polysulfate sodium, Azo-Standard
Type
Formula	C₁₁H₁₁N₅
Weight	Average: 213.2385 Monoisotopic: 213.101445377
Groups	Approved
Therapeutic Class
Manufacturer
Available Country
Last Updated:	September 19, 2023 at 7:00 am

Uses

Phenazopyridinum is a local anesthetic used for the symptomatic relief of pain, burning, urgency, frequency, and general discomfort caused by lower urinary tract irritations that are a result of infection, trauma, surgery, endoscopic procedures, or the passage of equipment or catheters.

Phenazopyridinum hydrochloride is indicated to relieve uncomfortable symptoms that occur as a consequence of mucosal irritation of the lower urinary tract in adults. The irritation may be a result of trauma, surgery, endoscopic procedures, infection, or the insertion of instruments or urinary catheters. Phenazopyridinum may be used in combination with antimicrobial therapy but is not used as an antimicrobial agent. It contributes to the relief of discomfort and pain before antimicrobial therapy begins to take effect. It is important to note that the duration of treatment with this drug should last a maximum of 2 days. Phenazopyridinum is available in many countries as an over the counter drug.

Phenazopyridinum is also used to associated treatment for these conditions: Lower Urinary Tract Infection, Signs or symptoms of urinary tract irritation

How Phenazopyridinum works

The full mechanism of action of phenazopyridine is not fully elucidated, however, it is reported to exert a direct topical analgesic effect on the mucosal lining of the urinary tract via the inhibition of voltage-gated sodium channels and possibly group A nerve fibers, as suggested by the results of a study in rats. The above actions likely lead to the relief of unpleasant urinary symptoms.

Toxicity

The oral LD50 of phenazopyridine in rats is 472 mg/kg.

Overdose information

Administering excess phenazopyridine above the daily recommended dose in those with healthy or impaired kidney function may increase the drug concentration and predispose the patient to toxicity. When a large overdose occurs, methemoglobinemia results. To treat this condition, Methylene blue at 1 to 2 mg/kg/dose should be administered intravenously as a 1% solution as deemed necessary. Its administration is likely to cause a rapid reduction of the methemoglobinemia state and relieve the associated cyanosis. Hemolytic anemia is also a risk when an overdose occurs, and “bite cells” may be observed in a blood smear after an overdose with phenazopyridine. Red blood cell G6PD deficiency may increase the risk of hemolysis, and even normal doses can lead to methemoglobinemia in patients with this condition. Nephrotoxicity, renal failure, and hepatic impairment may also occur in a case of overdose with this drug. Administer symptomatic and supportive treatment as necessary.

Food Interaction

Take with food. Food reduces irritation.

Phenazopyridinum Disease Interaction

Major: G-6-PD deficiency, hepatitis, renal dysfunction

Volume of Distribution

Small, trace quantities of phenazopyridine are thought to cross the placenta and the blood-brain barrier, reaching cerebrospinal fluid. A pharmacokinetic study in rats determined that phenazopyridine metabolites were present in high levels in the kidney and liver.

Elimination Route

Phenazopyridinum is absorbed in the gastrointestinal tract. The mean Cmax is 65.00 ± 29.23 ng/mL, the mean Tmax is 2.48 ± 0.50 h, and the mean AUC(0 – ∞)is 431.77 ± 87.82 ng.h/mL.

Half Life

The mean elimination half-life of phenazopyridine is 7.35 hours in rats with healthy renal function. The half-life in man is not readily vailable in the literature.

Clearance

This drug is rapidly excreted by the kidneys, up to 65% of a dose administered orally may be excreted as unchanged drug in the urine. The clearance of phenazopyridine may be decreased with impaired renal or hepatic function and is contraindicated in these conditions.

Elimination Route

Up to 65% of an oral phenazopyridine dose is quickly excreted by the kidneys as unchanged drug measured in the urine. The pharmacokinetics of this drug have not been evaluated in depth in man. In a small group of healthy research volunteers, 90% of a daily 600 mg oral dose of phenazopyridine hydrochloride was found to be excreted within 1 day, with 41% as unchanged drug and 49% as phenazopyridine metabolites. Another study in humans determined that 80.07 ± 4.54 percent of the dose was cleared in the urine within 48 hours of administration. In rats, biliary excretion was high, with 40.7% of a dose excreted in 8 hours.