Perioperative Hypoxia Secondary to Phenazopyridine-induced Methemoglobinemia in an Adolescent Patient Without Renal Insufficiency or Overdose: An Unusual Case

Shah, Parth; Kraft, Kate H.

doi:10.1016/j.urology.2019.03.017

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…Over-the-counter in the United States, the maximum dose obtainable is 199 mg per dose. It has been noted as the cause of methemoglobinemia in a few case reports [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. In most cases in the current literature, patients were taking the drug either for an extended period of time beyond the recommended two days or at a larger dosages than the recommended daily dose.…”

Section: Discussionmentioning

confidence: 99%

Phenazopyridine-Induced Methemoglobinemia in a Jehovah’s Witness Treated with High-Dose Ascorbic Acid Due to Methylene Blue Contradictions: A Case Report and Review of the Literature

et al. 2023

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Methemoglobinemia is an acute medical emergency that requires prompt correction. Physicians should have a high degree of suspicion of methemoglobinemia in cases that present with hypoxemia that does not resolve with supplemental oxygenation, and they should confirm this suspicion with a positive methemoglobin concentration on arterial blood gas. There are multiple medications that can induce methemoglobinemia, such as local anesthetics, antimalarials, and dapsone. Phenazopyridine is an azo dye used over-the-counter as a urinary analgesic for women with urinary tract infections, and it has also been implicated in causing methemoglobinemia. The preferred treatment of methemoglobinemia is methylene blue, but its use is contraindicated for patients with glucose-6-phosphatase deficiency or those who take serotonergic drugs. Alternative treatments include high-dose ascorbic acid, exchange transfusion therapy, and hyperbaric oxygenation. The authors report a case of a 39-year-old female who took phenazopyridine for 2 weeks to treat dysuria from a urinary tract infection and subsequently developed methemoglobinemia. The patient had contraindications for the use of methylene blue and was therefore treated with high-dose ascorbic acid. The authors hope that this interesting case promotes further research into the utilization of high-dose ascorbic acid for managing methemoglobinemia in patients who are unable to receive methylene blue.

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Section: Discussionmentioning

confidence: 99%

Phenazopyridine-Induced Methemoglobinemia in a Jehovah’s Witness Treated with High-Dose Ascorbic Acid Due to Methylene Blue Contradictions: A Case Report and Review of the Literature

et al. 2023

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“…Vitamin C is used as an alternative to methylene blue, which can precipitate haemolysis in G6PD-deficient patients. Hyperbaric oxygen and exchange transfusions are reserved for refractory cases [ 4 ] .…”

Section: Discussionmentioning

confidence: 99%

Phenazopyridine-Induced Methaemoglobinaemia - The Aftermath of Dysuria Treatment

Hamza

Nasrullah

Singh

et al. 2022

European Journal of Case Reports in Internal Medicine

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Introduction: Phenazopyridine is an over-the-counter urinary analgesic commonly used to alleviate the burning and urgency associated with lower urinary tract infections. Methaemoglobinaemia is an uncommon adverse effect of phenazopyridine use. We report a case of methaemoglobinaemia in a patient prescribed daily phenazopyridine to treat urethral and bladder irritation caused by a chronic indwelling Foley catheter. Case description: A 55-year-old female resident of a long-term acute care facility with a chronic Foley, tracheostomy and ventilator-dependent respiratory failure was observed to have generalized dusky skin and hypoxia. Pulse oximetry was reading in the high 80s despite administration of 100% FiO2. ABG revealed paO2 of 451, oxyhaemoglobin level 75% and methaemoglobin level 22%. Medication review indicated that the patient was prescribed phenazopyridine 400 mg TID for the previous 2 months. This medication was discontinued. Considering she was chronically taking mirtazapine, she can increase risk of serotonin syndrome should she be administered first-line treatment with methylene blue. Vitamin C was thus instead administered as a second-line agent. Serial ABGs showed a rapid decline in methaemoglobin levels and an increase in oxyhaemoglobin within 2 days. Discussion: Acquired methaemoglobinaemia is a rare adverse effect of treatment with phenazopyridine. This risk increases when drug dosage and duration exceed manufacturer specifications. Treatment typically includes cessation of the offending drug and administration of methylene blue in severe cases. A thorough medication reconciliation should be performed prior to methylene blue initiation, as patients taking serotonergic medications (for example, MAOIs, SSRIs, SNRIs, TCAs) are at increased risk of serotonin toxicity with co-administration of methylene blue. In these instances, ascorbic acid/vitamin C can be chosen as an alternative treatment agent. Conclusion: Work-up of refractory hypoxia should involve a thorough review of medications as even some over-the-counter drugs can cause the fatal side effect of methaemoglobinaemia. Treatment with vitamin C should be considered over methylene blue if serotonergic medications have been recently prescribed in order to avoid risk of serotonin syndrome.

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“…Phenazopyridine is a known cause of acquired methemoglobinemia. However, only a handful of cases have been reported in the literature in the last twenty years, summarized in ( Table 3 ) [ 5 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. The various patient factors such as chronic kidney disease, heart and lung disease, anemia, and inherent enzymes such as G6PD deficiency, Cytochrome b5 reductase (Cyb5R) deficiency, or heterozygotes variant with a lower than average baseline activity increase susceptibility for phenazopyridine-induced methemoglobinemia [ 16 ].…”

Section: Discussionmentioning

confidence: 99%

A Case of Severe Hypoxia Caused by Phenazopyridine-Induced Methemoglobinemia: A near Fatal Event from Over-the-Counter Medication Use

Subedi

Sharma

et al. 2022

Clinics and Practice

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Methemoglobinemia is a rare blood disorder characterized by the oxidation of heme iron from ferrous (Fe2+) to ferric (Fe3+) state, which increases oxygen affinity and impairs oxygen release to the tissue causing hypoxia. It can be congenital or acquired; however, most cases are acquired and caused by exogenous substances such as medications, chemicals, and environmental substances. Phenazopyridine is an over-the-counter urinary analgesic medication commonly used for symptomatic relief of dysuria and has been reported to cause methemoglobinemia. However, only a handful of cases of phenazopyridine-induced methemoglobinemia have been reported. We present a case of an 89-year-old female who presented with severe hypoxia, shortness of breath, headache, nausea, and dizziness caused by phenazopyridine-induced methemoglobinemia. She was found to have a methemoglobin level of 21.5% and was treated with methylene blue, leading to a rapid improvement of her symptoms. She was taking one over-the-counter phenazopyridine 200 mg tablet three times daily for two weeks for her chronic dysuria. This case highlights the need to have a high index of suspicion of phenazopyridine-induced methemoglobinemia in a patient presenting with unexplained shortness of breath with a history of phenazopyridine use as it could lead to severe methemoglobinemia with hypoxia that could potentially be fatal if not promptly diagnosed.

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Perioperative Hypoxia Secondary to Phenazopyridine-induced Methemoglobinemia in an Adolescent Patient Without Renal Insufficiency or Overdose: An Unusual Case

Cited by 6 publications

References 11 publications

Phenazopyridine-Induced Methemoglobinemia in a Jehovah’s Witness Treated with High-Dose Ascorbic Acid Due to Methylene Blue Contradictions: A Case Report and Review of the Literature

Phenazopyridine-Induced Methemoglobinemia in a Jehovah’s Witness Treated with High-Dose Ascorbic Acid Due to Methylene Blue Contradictions: A Case Report and Review of the Literature

Phenazopyridine-Induced Methaemoglobinaemia - The Aftermath of Dysuria Treatment

A Case of Severe Hypoxia Caused by Phenazopyridine-Induced Methemoglobinemia: A near Fatal Event from Over-the-Counter Medication Use

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