Chocolate-Colored Blood With Normal Artery Oxygen: Methemoglobinemia Related to Phenazopyridine

Yu, Chao-Hung; Wang, Chu-Hsien; Chang, Chia‐Chu

doi:10.1097/maj.0b013e3181df9369

Cited by 9 publications

(3 citation statements)

References 1 publication

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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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“…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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“…Most cases of methaemoglobinaemia are acquired, resulting from an increased methaemoglobin formation by various exogenous agents. The classical drugs causing methaemoglobinaemia include analgesics (lidocaine and phenazopyridine), antibiotics (sulphonamides and dapsone), nitrites/nitrates, nitroprusside and metoclopramide 2. The clinical presentations of methaemoglobinaemia include cyanotic appearance, unresponsive to oxygen therapy; low oxygen saturation on pulse oximeter, which does not match high PaO 2 .…”

Section: Introductionmentioning

confidence: 99%

Acquired methaemoglobinaemia related to phenazopyridine ingestion

Shahani

Sattovia

2012

BMJ Case Reports

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SummaryMethaemoglobin is an altered state of haemoglobin in which the ferrous ions of haeme are oxidised to the ferric state. This results in increased affinity to the bound oxygen and decreasing its availability to tissues. Most cases of methaemoglobinaemia are acquired, resulting from an increased methaemoglobin formation by various exogenous agents. The authors report an elderly patient presenting to the emergency department with a 1-month history of shortness of breath. Around the same time she had started using over-the-counter (OTC) phenazopyridine tablets for urinary symptoms. The patient was hypoxic and cyanotic; however, lacked evidence of hypoxaemia on the arterial blood gas. The presence of abnormal haemoglobin was suspected and confirmed by elevated levels of methaemoglobin. Phenazopyridine was proposed to be the likely aetiology of the methaemoglobinaemia, which the patient was not aware of. This case highlights the importance of always inquiring the OTC drug use especially in geriatric population. BACKGROUND

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Chocolate-Colored Blood With Normal Artery Oxygen: Methemoglobinemia Related to Phenazopyridine

Cited by 9 publications

References 1 publication

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

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

Acquired methaemoglobinaemia related to phenazopyridine ingestion

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