Fomepizole in the treatment of ethylene glycol poisoning

Characterization of a Human Respiratory Mucosa Model to Study Odorant Metabolism

Nasal xenobiotic metabolizing enzymes (XMEs) are important for the sense of smell because they influence odorant availability and quality. Since the major part of the human nasal cavity is lined by a respiratory mucosa, we hypothesized that this tissue contributed to nasal odorant metabolism through XME activity. Thus, we built human respiratory tissue models and characterized the XME profiles using single-cell RNA sequencing. We focused on the XMEs dicarbonyl and l-xylulose reductase, aldehyde dehydrogenase (ALDH) 1A1, and ALDH3A1, which play a role in food odorant metabolism. We demonstrated protein abundance and localization in the tissue models and showed the metabolic activity of the corresponding enzyme families by exposing the models to the odorants 3,4-hexandione and benzaldehyde. Using gas chromatography coupled with mass spectrometry, we observed, for example, a significantly higher formation of the corresponding metabolites 4-hydroxy-3-hexanone (39.03 ± 1.5%, p = 0.0022), benzyl alcohol (10.05 ± 0.88%, p = 0.0008), and benzoic acid (8.49 ± 0.57%, p = 0.0004) in odorant-treated tissue models compared to untreated controls (0 ± 0, 0.12 ± 0.12, and 0.18 ± 0.18%, respectively). This is the first study that reveals the XME profile of tissue-engineered human respiratory mucosa models and demonstrates their suitability to study nasal odorant metabolism.

Antidotes Against Methanol Poisoning: A Review

Methanol is the simplest alcohol. Compared to ethanol that is fully detoxified by metabolism. Methanol gets activated in toxic products by the enzymes, alcohol dehydrogenase and aldehyde dehydrogenase. Paradoxically, the same enzymes convert ethanol to harmless acetic acid. This review is focused on a discussion and overview of the literature devoted to methanol toxicology and antidotal therapy. Regarding the antidotal therapy, three main approaches are presented in the text: 1) ethanol as a competitive inhibitor in alcohol dehydrogenase; 2) use of drugs like fomepizole inhibiting alcohol dehydrogenase; 3) tetrahydrofolic acid and its analogues reacting with the formate as a final product of methanol metabolism. All the types of antidotal therapies are described and how they protect from toxic sequelae of methanol is explained.

Severe hypernatremia and transient azotemia in a cat following inadvertent intravenous administration of a commercial polyethylene glycol solution

OBJECTIVE

To describe the clinical signs, clinicopathologic abnormalities, treatment, and outcome after IV administration of polyethylene glycol 3350 (PEG3350) in a cat.

CASE SUMMARY

A cat was inadvertently administered 6 g/kg of PEG3350 in electrolyte solution, IV, resulting in severe hypernatremia (203 mmol/L), diffuse encephalopathy, hemolysis, and moderate azotemia. The hemolysis and acute kidney injury observed immediately following PEG3350 administration resolved with supportive care. Administration of IV and oral electrolyte-free water slowly corrected the hypernatremia and the neurologic signs subsequently improved. Complete resolution of clinical signs was documented one month following hospital discharge. The PEG3350 concentrations in serum, plasma, and urine samples confirmed toxic exposure to PEG3350. Efficacy of treatment was evident by decreasing concentrations of PEG3350 in serum after the first 24 hours of treatment. Renal elimination of PEG3350 was significant and PEG3350 was still detected in the urine 17 days after exposure.

NEW INFORMATION PROVIDED

This is the first report to describe the clinical signs and clinicopathologic abnormalities in a cat intoxicated with IV PEG3350. Potential pathophysiologic mechanisms are discussed, and the successful supportive medical treatment is outlined.

Stiripentol protects against calcium oxalate nephrolithiasis and ethylene glycol poisoning

Increased urinary oxalate excretion (hyperoxaluria) promotes the formation of calcium oxalate crystals. Monogenic diseases due to hepatic enzymes deficiency result in chronic hyperoxaluria, promoting end-stage renal disease in children and young adults. Ethylene glycol poisoning also results in hyperoxaluria promoting acute renal failure and frequently death. Stiripentol is an antiepileptic drug used to treat children affected by Dravet syndrome, possibly by inhibiting neuronal lactate dehydrogenase 5 isoenzyme. As this isoenzyme is also the last step of hepatic oxalate production, we hypothesized that Stiripentol would potentially reduce hepatic oxalate production and urine oxalate excretion. In vitro, Stiripentol decreased in a dose-dependent manner the synthesis of oxalate by hepatocytes. In vivo, Stiripentol oral administration reduced significantly urine oxalate excretion in rats. Stiripentol protected kidneys against calcium oxalate crystal deposits in acute ethylene glycol intoxication and chronic calcium oxalate nephropathy models. In both models, Stiripentol improved significantly renal function. Patients affected by Dravet syndrome and treated with Stiripentol had a lower urine oxalate excretion than control patients. A young girl affected by severe type I hyperoxaluria received Stiripentol for several weeks: urine oxalate excretion decreased by two-thirds. Stiripentol is a promising potential therapy against genetic hyperoxaluria and ethylene glycol poisoning.

[Severe acute ethylene glycol poisoning: diagnostic utility of osmolar gap monitoring]

Ethylene glycol intake is a rare cause of alcohol poisoning in our practice setting. Most cases are voluntary, representing suicide attempts. Because delayed treatment leads to serious morbidity and high mortality (up to 50%), early diagnosis is essential for preventing harmful consequences and even death. Diagnosis is based on clinical suspicion and laboratory findings. Given that most hospitals do not have the means to measure the specific toxin in plasma, osmolar gap monitoring usually serves as a rapid diagnostic test for detecting the presence of osmotically active substances like ethylene glycol in plasma. We report a case of voluntary poisoning after the patient swallowed antifreeze. Successful treatment began early, with monitoring of the osmolar gap and plasma level correspondence. We also comment on the range of therapeutic options, emphasizing antidotes such as ethanol and fomepizole which provide the basis for treatment.

The management of severe toxic alcohol ingestions at a tertiary care center after the introduction of fomepizole

INTRODUCTION

Ethylene glycol and methanol ingestions are relatively uncommon but potentially lethal poisonings. Recent trials have demonstrated that fomepizole effectively blocks alcohol dehydrogenase (ADH) in toxic alcohol overdoses, and may eliminate the need for emergent hemodialysis and intensive care unit admission. However, controversy remains in the role of fomepizole in clinical practice. The purpose of this study was to describe the presentation, management and clinical course of toxic alcohol ingestions at a tertiary care referral center after the introduction of fomepizole to hospital formulary.

METHODS

Data was collected on all patents treated for toxic alcohol ingestions for a 1-year period in a tertiary care referral center. Patients who received fomepizole or ethanol infusions, or who underwent hemodialysis were identified by ED, pharmacy, hemodialysis and ICU databases. The patients' medical records were reviewed, and data was recorded on a predetermined computerized data collection form.

RESULTS

Overall, twenty (20) toxic ingestions (14 methanol; 6 ethylene glycol) were identified over the one year period. Fomepizole was used for ADH blockade in 12/20 cases; ETOH infusions in 15/20 cases (combined ETOH and fomepizole use in 7/20). The majority of toxic alcohol exposures were admitted to an intensive care unit (19/20) and received emergent hemodialysis (19/20). All patients were discharged from hospital alive.

CONCLUSIONS

Patients with methanol and ethylene glycol ingestions who presented to our centers had significant toxicity and received both HD and ICU admission. Further research is required to determined if the method of ADH blockade affects the need for hemodialysis or ICU admission in toxic alcohol ingestions.