ARTICLES
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Urology Nurses Online: ARTICLES |
Joyce R. Cornwell is an Assistant Professor in the Department of Adult Health and Illness Nursing at the University of Nebraska Medical Center in Omaha, Nebraska.
Jean Krajicek Bartek is an Associate Professor in the Departments of Adult Health and Illness Nursing and Pharmacology at the University of Nebraska Medical Center in Omaha, Nebraska.
This article is reprinted with permission of the Society of Urologic Nurses and Associates (SUNA) from Urologic Nursing (1996), 16 (4), p. 153-4, (published by Mosby Yearbook Incorporated).
Medications containing phenazopyridine hydrochloride are found in prescription form and increasingly in over-the-counter preparations. There are also medications (prescription) that combine this agent with antibiotic, anticholinergic, and barbiturate agents. The primary purposes of this article are to briefly address selected effects and to outline important client teaching when phenazopyridine hydrochloride is used.
Phenazopyridine is an azo dye and urinary tract analgesic without antibacterial properties. It is compatible with antibacterial therapy and is frequently used as an adjunct to such therapy because it helps to relieve pain and discomfort before the antibacterial agent controls the infection. Although its specific mechanism of action in unknown, it exerts a topical analgesic effect on the urinary tract mucous and provides symptomatic relief of burning, urgency, frequency, pain, and other discomforts arising from irritation of the lower urinary tract caused by infection, trauma, surgery, endoscopic procedures, or the passage of sounds or catheters. Its analgesic action may reduce or eliminate the need for systemic analgesics. It is used solely for relief of symptoms.
Clients should be taught that symptomatic treatment of a urinary tract infection with phenazopyridine hydrochloride should be limited to 2 days, because there is a lack of evidence that the combined administration of the medication and an antibacterial agent provides greater benefit than administration of the antibacterial agent alone after 2 days. It is NOT intended for long-term use to treat undiagnosed urinary tract pain, although the uninformed patient may use it this way. Clients should also be taught that chronic use to treat undiagnosed pain of the urinary tract could lead to serious delays in appropriate diagnosis and treatment and to adverse responses related to the medication. Per review of the literature it is interesting to note that such events as "surreptitious ingestion for several months," "prolonged use," "ingestion with suicidal intent", and accidental overdosage have occurred.
The absorption and distribution of phenazopyridine hydrochloride have not been described, although traces are thought to enter the cerebrospinal fluid and cross the placenta. It is metabolized in the liver and other tissues and excreted in the urine, where it exerts its action. Nearly 90% of an oral dose is excreted renally in 24 hours. Because this medication can cause changes in urine color that are not related to disease, the client should be told that the urine will become reddish-orange and may stain fabric and that staining of the contact lenses has been reported. Clients who are not informed of this often become concerned that the color change is due to a bleeding problem. Phenazopyridine hydrochloride should be taken with or after meals to decrease gastric distress. There are no adequate or well-controlled studies in pregnant women; no information is available on the appearance of this drug or its metabolites in breast milk. Use in children younger than 12 years of age should be directed by a physician. Phenazopyridine hydrochloride is contraindicated in persons with known hypersensitivity to phenazopyridine and in persons with renal and hepatic insufficiency because of the potential for drug accumulation.
Persons taking phenazopyridine hydrochloride should be taught to report urinary tract symptoms that worsen or do not resolve. They should be made aware of the manifestations of possible adverse reactions that may occur, although uncommonly. According to the literature adverse reactions may include methemoglobinemia, renal and hepatic impairment and failure, and hemolytic anemia.
The formation of methemoglobin is a normal process kept in bounds by the reduction of methemoglobin to hemoglobin. Phenazopyridine hydrochloride has been associated with methemoglobinemia in persons who have received overdosage, have decreased renal function, or are discovered to be unusually susceptible to the medication.1,2 Methemoglobinemia is thought to be caused when the iron in the heme portion of deoxygenated hemoglobin is oxidized to a ferric rather than a ferrous form.3 Oxygen and iron cannot be combined in the ferric form, resulting in anoxia and cyanosis (periorbital, nailbed and extreme cyanosis which can be noticed by the client and others) in the absence of hemodynamic instability and cardiopulmonary disease. Methemoglobinemia decreases oxygen-carrying capacity and shifts the oxygen disassociation curve to the left, decreasing release of oxygen peripherally to the tissues. Laboratory determination of methemoglobin and hemoglobin M values is useful in the diagnosis of hereditary or acquired methemoglobinemia in persons with symptoms of anoxia or cyanosis without evidence of cardiovascular or pulmonary disease.3
Significant cellular hypoxia will develop if methemoglobinemia progresses untreated. Persons with high methemoglobin levels have symptoms reflecting decreased peripheral delivery of oxygen, such as stupor, and tachycardia. The primary goal of treatment of methemoglobin is to increase the patient's oxygen-carrying capacity. Depending on the specific situation treatment may include gastric lavage and activated charcoal administration, methylene blue administration, and blood transfusion in severe refractory cases.4
Renal failure can occur as a complication of phenazopyridine-related methemoglobinemia and hemolytic anemia. As previously mentioned, phenazopyridine hydrochloride is contraindicated in clients with impaired renal and hepatic function. For this reason use of this agent in the elderly is very limited. The agent should not be used in clients with a creatinine clearance less than 50 ml/min.5 All clients taking this medication should be instructed to observe for a yellow appearance of the skin and sclera. This may indicate an accumulation of the drug owing to renal impairment AND A NEED TO DISCONTINUE THERAPY. If discoloration occurs, the drug should be immediately discontinued and the prescriber immediately notified. Color changes in skin or sclera can also indicate hepatotoxicity.
It is alarming that phenazopyridine-induced anemia has occurred both after overdoses and after recommended doses of the drug.6 The anemia induced has been characterized as oxidative Heinz-body hemolytic anemia, a toxic action on red blood cells. Heinz bodies are small irregular particles of hemoglobin detected on peripheral blood smear examination. Persons with hemolytic anemia may have no initial clinical signs or symptoms.
Non-dose-related hypersensitivity hepatitis reactions have also been documented with the use of phenazopyridine hydrochloride. There have also been reports of urinary phenazopyridine stone development with extended use.7
Phenazopyridine hydrochloride may interfere with urinalysis based on spectrometry or color reactions. There is some evidence that the results of the leukocyte esterase dipsticks should be interpreted with caution in patients taking this agent until further studies clarify the possible interaction of this medication and the dipstick. It may give a false-negative reading. Phenazopyridine may cause delayed reactions with glucose oxidase reagents, but cupric sulfate tests are not affected. It may also interfere with urine ketone and urinary protein tests.5
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