WBR0933
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Renal, SubCategory::General Principles |
| Prompt | [[Prompt::A 6-year-old male is brought to the emergency room by his parents after he began exhibiting signs of intoxication and vomiting. The patient reports that the symptoms started after he drank a blue liquid and he now has flank pain. The patient has an anion gap of 22 (normal: 11-18) with serum bicarbonate of 7 mEq/L and creatinine of 5.6 mg/dL. Urinalysis reveals hematuria. Which of the following should be administered to this patient?]] |
| Answer A | AnswerA::Fomepizole |
| Answer A Explanation | AnswerAExp::Correct: Fomepizole is a potent inhibitor of alcohol dehydrogenase; similar to ethanol, it acts to block the formation of the toxic metabolites. It is primarily used as an antidote to ethylene glycol poisoining. |
| Answer B | AnswerB::Flumazenil |
| Answer B Explanation | AnswerBExp::Incorrect: Flumazenil is a benzodiazepine receptor antagonist used to treat benzodiazepine overdose. |
| Answer C | AnswerC::Disulfiram |
| Answer C Explanation | [[AnswerCExp::Incorrect: Disulfiram is an inhibitor of acetaldehyde dehydrogenase, an enzyme that metabolizes acetaldehyde to acetate. The accumulation of acetaldehyde caused by concurrent disulfiram and ethanol ingestion causes unpleasant side effects. For this reason, disulfiram is used to help alcoholics stop drinking.]] |
| Answer D | AnswerD::Glucagon |
| Answer D Explanation | AnswerDExp::Incorrect: Glucagon can be used to treat beta-blocker overdose. |
| Answer E | AnswerE::Ammonium Cholride |
| Answer E Explanation | AnswerEExp::Incorrect: Ammonium chloride can be given for methamphetamine overdose. It helps to acidify the urine and increase renal clearance of the drug. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Children are the most frequent victims of ethylene glycol poisoning. Ethylene glycol can be found in items such as antifreeze, and has a sweet taste which can cause children to drink it. Ethylene glycol itself is not toxic, but its metabolites are. Ethylene glycol is first metabolized to glycolaldehyde, which then undergoes further oxidation to glycolate, glyoxylate, and oxalate. It is glycolate and oxalate that are primarily responsible for the metabolic acidosis and renal damage that accompany ethylene glycol poisoning. The antidotes to ethylene glycol poisoning are ethanol and fomepizole, both of which inhibit the metabolism of ethylene glycol. Ethanol competitively inhibits the metabolism of ethylene glycol by alcohol dehydrogenase. Fomepizole is also a competitive inhibitor of alcohol dehydrogenase. Hemodialysis should be initiated in any patient with known ethylene glycol or methanol poisoning.
Educational Objective: Fomepizole acts as an antidote to ethylene glycol poisoning by competitive inhibition of alcohol dehydrogenase. References: First Aid 2012 page 270 First Aid 2013 page 239 |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Poisoning, WBRKeyword::Ethylene glycol, WBRKeyword::Alcohol, WBRKeyword::Antidote, WBRKeyword::Toxin |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |