UMEM Educational Pearls - Toxicology

Category: Toxicology

Title: Valproic Acid and its Unique Antidote

Keywords: valproic acid, poisoning, carnitine (PubMed Search)

Posted: 10/11/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Valproic Acid (Depakote) - Increased use for both seizure disorder, migraine prophylaxis and bipolar disorder - Causes hyperammonemia with or without hepatic insufficiency (Liver enzymes could be normal!) - Hyperammonemia can occur at therapeutic concentrations and overdose - If the patient is sedated and has hyperammonemia, consider carnitine therapy antidotal - Carnitine IV or PO: 50-100 mg/kg bolus or divided bid, safe to give


Category: Toxicology

Title: Rubbing Alcohol - Dangerous?

Keywords: Isopropanol, toxic alcohol, poisoning (PubMed Search)

Posted: 10/4/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Isopropanol (Commonly Rubbing Alcohol)
  • Rubbing alcohol is 70% isopropanol, like drinking Bacardi 151 (151 proof)
  • This is NOT a toxic alcohol in the traditional sense
  • This causes a large ketosis, large osmol gap but NO anion gap and no acidosis
  • This is because isopropanol is metabolized to acetone (a ketone) not an acid
  • Toxicity: inebriation, hemorrhagic gastritis, sedation to the point of death/intubation

Category: Toxicology

Title: Ciguatera Poisoning

Keywords: ciguatera, poisoning, fish (PubMed Search)

Posted: 9/27/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Ciguatera Poisoning - The most commonly reported cause of fishborne poisoning - Most commonly big-game fish: sea bass, grouper, red snapper, yellow-tail, kingfish and sturgeon - Ciguatoxin is bioaccumulated (thus big fish) and is heat and acid stable (unaffected by cooking) - Symptoms: 6-12 hrs post-ingestion GI, paresthesias, metallic taste, ataxia and paresis of legs are possible - The classic symptom is dysesthesias (sensory reversal where cold gives intense burning sensation) - Treatment: Supportive, consider mannitol, calcium, gabapentin - Avoid the following as it may exacerbate symptoms: opioids, barbiturates, steroids

Category: Toxicology

Title: Ethanol Withdrawal

Keywords: ethanol, withdrawal, benzodiazepines (PubMed Search)

Posted: 9/18/2007 by Fermin Barrueto, MD (Emailed: 9/20/2007) (Updated: 12/8/2022)
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Ethanol withdrawal can be measure objectively with the CIWA-Ar Scale. It is a prospectively validated tool to measure whether or not a patient is in ethanol withdrawal and can assist with management. Score Treatment <10 Does not require treatment 10-15 Treatment with either oral or intravenous benzodiazepines, outpatient > 15 Intravenous benzodiazepines with likely admission You must also take into account the patient's history, comorbidities and previous history of ethanol withdrawal/delirium tremens. ***The CIWA Score Sheet has been attached to this pearl***

Attachments

ciwa-ar.pdf (10 Kb)


Category: Toxicology

Title: Toxins that cause Diabetes or Hyperglycemia

Keywords: Hyperglycemia, diabetes, poisoning (PubMed Search)

Posted: 9/13/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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There are few medications/toxins that can cause clinically significant diabetes or hyperglycemia, here is the list: Vacor (PNU, an off the market rat poison) Streptozocin Alloxan Pentamidine Quinolones (gatifloxacin>moxifloxacin>ciprofloxacin) Olanzapine Antidote for Vacor, streptozocin, Alloxan: Niacinamide Antidote for Quinolones, Olanzapine: Remove agent, supportive care

Category: Toxicology

Title: Scombroid

Keywords: Fish, scombroid, seafood poisoning (PubMed Search)

Posted: 9/6/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Scombroid is one of the most common seafood poisonings. A classic EM board question. - Caused by ingestion of histamine in fish muscle - Naturally occurring histidine is converted to histamine by bacteria in unrefrigerated fish - Most common fish: tuna, mackerel, bonito, mahi mahi, blue fish and yellow tail - Symptoms: Within minutes to hours - flushing, urticaria, perioral burning, N/V/D - Treatment: Antihistamines, fluids, bronchodilators. Epinephrine and steroid for severe reactions.

Category: Toxicology

Title: Methemoglobinemia

Keywords: pyridium, methemoglobinemia, methylene blue (PubMed Search)

Posted: 8/30/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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- Classic Clinical Finding: Cyanosis out of proportion to clinical symptoms (look real blue but not SOB) - Causative Agents: Benzocaine (and other local anesthetics), dapsone, nitrites, phenazopyridine (Pyridium) - When do you treat: significant tissue hypoxia (MI, CVA, Dysrhythmias), and if MetHb >20% asymptomatic - Treatment: Methylene Blue 1-2 mg/kg (0.1 -0.2 mL/kg of 1% methylene blue) over minutes

Category: Toxicology

Title: Colchicine Toxicity - The Point of No Return

Keywords: Colchicine, toxicity, poisoning (PubMed Search)

Posted: 8/23/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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- Few medications are uniformly lethal after a certain amount is ingested. - Colchicine is one of those medications, >0.8 mg/kg ingested=100%mortality regardless of treatment. - Many people prescribe it without knowing the adverse effect profile. - In fact, the prescribing instructions tell you to take the patient to toxicity (nausea and vomiting). - After an acute overdose this would be the sequence of events assuming surivival: Phase Signs & Symptoms i Nausea, vomiting, diarrhea, dehydration, leukocytosis (0-24hrs) II Sudden cardiac death (24-36hrs), pancytopenia, renal failure sepsis, ARDS, rhabdo (1-7d) III Alopecia, myopathy, neuropathy, myoneuropathy (>7d) - Colchicine prevents/destroys microtubule spindle formation and thus acts like a chemotherapeutic agent killing the cells that replicate most. - Think twice when prescribing this medication to someone, especially a patient at risk for suicide or medication noncompliance (where they think a little is good so more is better).

Category: Toxicology

Title: Local Anesthetics

Keywords: lidocaine, allergic reaction, toxicity (PubMed Search)

Posted: 8/16/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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- Allergic reactions are extremely rare to local anesthetics but may occur with the "Amides". - If they occur, it is more likely due to a preservative found in some multi-dose vials: methylparaben. - Either switch to a single dose vial without preservative or change to an "Ester" where there is no cross-reactivity Amides: Bupivacaine, Etidocaine, Lidocaine, Mepivacaine, Prilocaine, Ropivacaine Esters: Chloroprocaine, cocaine, procaine, tetracaine

Category: Toxicology

Title: Toxic Findings on CxR

Keywords: Chest radiograph, poisoning, amiodarone (PubMed Search)

Posted: 8/9/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Here are some chest x-ray findings and cool toxins that can cause them (not an all-inclusive list): Diffuse airspace filling: salicylates, opioids, paraquat, phospgene, doxorubicin - Disease Process: Acute Lung Injury Focal airspace filling: hydrocarbons - Disease Process: Aspiration pneumonitis Pleural Effusion: Procainamide, hydralazine, INH, methyldopa - Disease Process: Drug-induced SLE Pneumothorax/Pneumomediastinum: "crack" cocaine and marijuana, IVDA into subclavian vein - Disease Process: Barotrauma Lymphadenopathy: Phenytoin, methotrexate - Disease Process: Pseudolymphoma Interstitial Patterns: Amiodarone - Disease Process: Phospholipidosis [Adapated from Goldfrank's Textbook of Toxicologic Emergencies, 8th Edition, Table 6-3, p. 74]

Category: Toxicology

Title: Opioids with Unique Toxicity

Keywords: opioids, adverse drug effect, methadone (PubMed Search)

Posted: 8/2/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Opioids Opioids in general cause respiratory depression, miotic pupils and some mild hypotensions and bradycardia when the patient is comatose. All opioids can cause varying degrees of histamine release. However, not all opioids are similiar, here are the unique toxicities of some various opioids - keep them in mind when you prescribe them: 1) Propoxyphene - seizures and TCA like effects, also not very effect analgesic 2) Meperidine - seizures, serotonergic (thus increased abuse potential) 3) Methadone - long half-life (30+hrs) and QT prolongation 4) Hydromorphone - rare seizures and most common opioid that causes iatrogenic overdose because of its potency. (Easy to write 2 mg of "Dilaudid" but that is equivalent to 14 mg of morphine!) 5) Tramadol - seizure (common) and serotonergic, this is only 20% opioid 6) Fentanyl - rigid chest syndrome with rapid IV administration causes intercostal muscle contraction - not good

Category: Toxicology

Title: Chemical Weapons of Mass Destruction

Keywords: Nerve agents, organophosphates, blistering agents (PubMed Search)

Posted: 7/26/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Chemical Weapons of Mass Destruction There are a variety of chemicals utilized as WMD and can be categorized as: nerve agent, blistering agent or incapacitating agent: Nerve Agents: (Sarin, VX) cause a parasympathetic toxidrome due to inhibition of Acetylcholinesterase. Antidote is pralidoxime, benzodiazepines and atropine. Blistering Agents: (Mustard Gas) Must be treated like a severe burn patient causing extreme pain and sloughing of the skin. Incapacitating Agents: (BZ) Causes anticholinergic toxidrome, your whole army starts to hallucinate and develop urinary retention. People armed, hallucinating and needing to pee makes for a highly ineffective military force.

Category: Toxicology

Title: Activated Charcoal

Keywords: Gastrointestinal decontamination, activated charcoal, poisoning (PubMed Search)

Posted: 7/19/2007 by Fermin Barrueto, MD (Updated: 12/8/2022)
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Gastrointestinal Decontamination - Activated Charcoal Pharmacist P.f. Touery, in 1831, making a demonstration of the effectiveness of charcoal before the French academy of Medicine, survived after swallowing 15 g of strychnine (10x lethal dose) and an equal amount of charcoal - 3 tablespoons. (That's for you Dr. Rolnick) - Assess the patients' chance of becoming unresponsive or vomiting in relation to the ingestion if known. - Maximal benefit if given within 1 hour of ingestion, drug is likely still in the stomach. - No study has yet to show decrease in morbidity or mortality when empirically given to all ingestions. - Only one study has shown multi-dose activated charcoal to decrease morbidity and mortality and that was with a drug (oleander is like digoxin) that is enterohepatically metabolized. de Silva HA, et al. Multiple-dose activated charcoal for treatment of yellow oleander poisoning: a single-blind, randomised, placebo-controlled trial. Lancet. 2003 Jun 7;361(9373):1935-8.

Category: Toxicology

Title: One Pill Killers for Children

Keywords: pediatric, poisoning, overdose (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/12/2007) (Updated: 12/8/2022)
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One Pill Killers for Children Drug Class Mechanism of Action that Kills Sulfonylureas These hypoglycemic agents (ie. Glyburide) also have a long t Opioids Respiratory depression Imidazoline Clonidine and Oxymetazolone (nasal spray) cause bradycardia and respiratory depression Ca Channel Blockers Bradycardia & hypotension, especially diltiazem and verapamil Beta Blockers Extended release preparations are problematic There are some others but these are the most commonly prescribed pharmaceuticals. Remember, children under age 6 will not be able to swallow a pill and the pill itself is choking hazard. Proper poison prevention education for the parents is also needed.

Category: Toxicology

Title: Hydrofluoric Acid (HF)

Keywords: hydrofluoric acid, hypocalcemia, burn (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Hydrofluoric Acid (HF) Used in glass etching, brick/porcelain cleaning and available in hardware stores Death has been reported after JUST 2-3% body surface area exposure! Systemic toxicity: hypocalcemia, hyperkalemia and hypomagensemia Local effects: paucity of skin findings with tremendous pain Treatment: skin decontamination, correct electrolyte abnormalities and topical calcium gel for local pain Mayer TG, GrossPI. Fatal systemic fluoride due to hydrofluoric acid burns. Ann Emerg Med 1985; 14: 149-153.

Category: Toxicology

Title: Toxic Alcohols

Keywords: Ethylene glycol, methanol, toxic alcohol (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Toxic Alcohols Unexplained anion gap metabolic acidosis => give fomepizole (antidote) Hypokalemia, hypocalcemia, elevated creatinine => think ethlylene glycol Visual disturbances => think methanol Ketosis without acidosis and high osmol gap => think isopropanol If osmol gap is >70; high specificity for a toxic alcohol ingestion

Category: Toxicology

Title: Acetaminophen Toxicity

Keywords: acetaminophen, hepatic failure, hepatitis (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Acetaminophen Toxicity Hepatoxicity defined by AST >1000 King s College Criteria to prognosticate hepatic failure and need for transplant: o pH <7.3 o Creatinine >3.4 mg/dL o INR >6.5 o Hepatic encephalopathy Grade III or IV Low phosphate (<1.2 mmol/L) may be predictor of survival and elevated may be indicator of impending hepatic failure. (Especially 48 96 hrs post-ingestion) o Theory is phosphate used in regeneration/healing liver Gow PJ, Sood S, Angus PW. Serum phosphate as a predictor of outcome in acetaminophen-induced fulminant hepatic failure. Hepatology. 2003; 37(3):711.

Category: Toxicology

Title: Botulinum Toxin

Keywords: botulinum toxin, paralysis, heroin (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Botulinum Toxin Most potent toxin on the planet where 7 picograms IV are lethal to a human Characterized by a descending flaccid paralysis w/o fever bulbar findings 1st Weapon of Mass Destruction but also seen in the IVDA Heroin population Black Tar Heroin outbreak with necrotic ulcers that produced C. botulinum o Most recently in Washington DC 2003 Centers for Disease Control and Prevention (CDC). Wound botulism among black tar heroin users--Washington, 2003. MMWR Morb Mortal Wkly Rep. 2003;52(37):885-6.

Category: Toxicology

Title: Diagnosing Salicylate Toxicity

Keywords: Salicylate, aspirin, ferric chloride (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Diagnosing Salicylate Toxicity - Acute ingestion can initiially present with nausea, vomiting and a respiratory alkalosis - Toxicity defined by an anion gap metabolic acidosis with ketosis and normal glucose - Ferric chloride test (can get from chemistry set): couple of drops into urine, if it changes color to deep purple sensitive positive for presence of salicylate (sensitive but not specific)

Category: Toxicology

Title: Hyperthermia

Keywords: hyperthermia, serotonin syndrome, neuroleptic malignant syndrome (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto, MD (Emailed: 7/8/2007) (Updated: 12/8/2022)
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Hyperthermia Neuroleptic Malignant Syndrome (Dopamine Inhibition): treat with bromocriptine Serotonin Syndrome (5-HT1A agonism): treat with serotonin antagonist Malignant Hyperthermia (Genetic): treat with dantrolene