UMEM Educational Pearls - Toxicology

Title: Local Anesthetics

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

Posted: 8/16/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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

Title: Toxic Findings on CxR

Category: Toxicology

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

Posted: 8/9/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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]

Title: Opioids with Unique Toxicity

Category: Toxicology

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

Posted: 8/2/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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

Title: Chemical Weapons of Mass Destruction

Category: Toxicology

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

Posted: 7/26/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: Activated Charcoal

Category: Toxicology

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

Posted: 7/19/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: One Pill Killers for Children

Category: Toxicology

Keywords: pediatric, poisoning, overdose (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: Heavy Metal Poisoning Clues for Diagnosis

Category: Toxicology

Keywords: metal, poisoning, thallium (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Heavy Metal Poisoning Clues for Diagnosis Mees lines, indication of arrested nail growth, occurs in lead, arsenic and others Most heavy metals will cause a proteinuria Microcytic anemia and basophilic stippling seen in lead, arsenic, mercury Peripheral neuropathies in otherwise healthy person Thallium causes classic painful paresthesias in lower extremities

Title: Urine Drug Screens

Category: Toxicology

Keywords: drug abuse, urine drug screen, cocaine (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Urine Drug Screens Though we order them often, be sure you know what your results mean: Cannabinoids: an accurate test though clinically not important information, positive for 5 days to a full month with chronic users. Cocaine: the most accurate and precise test, positive for 3-5 days. Amphetamine: the most imprecise with many false positives and false negatives. Cough/cold preparations that contain pseudephedrine, phenylephrine or other decongestants can turn it falsely positive. BDZ: only benzodiazepines that are metabolized to oxazepam will turn positive. You can see false negatives with alprazolam and even lorazepam. Opioids: Semisynthetics like oxycodone and hydrocodone may give false negatives at low levels. This screen will NOT catch methadone, meperidine, fentanyl, propoxyphene, tramadol. PCP: False positives from dextromethorphan and ketamine

Title: Tricyclic Antidepressants (TCA)

Category: Toxicology

Keywords: tricyclic antidepressant, electrocardiogram, cardiac toxicity (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Tricyclic Antidepressants (TCA) - Lack of terminal 40msec R wave (R wave in AvR, S wave in I, AvL) means the patient is NOT TCA toxic. - 40msec R wave + QRS >100msec = possible TCA toxicity, treat with NaHCO3 and recheck ECG. - TCA toxicity defined by ECG; if QRS > 100msec, 33% seizures; if QRS > 160msec, 50% v tach Boehnert MT, Lovejoy FH Jr. Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants. N Engl J Med. 1985 Aug 22;313(8):474-9.

Title: Digoxin Toxicity

Category: Toxicology

Keywords: digoxin, cardiac glycoside, toxicity (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Digoxin Toxicity Most common finding on ECG when digoxin toxic: PVCs Most classic ECG in digoxin toxicity: PAT with block Pathognomonic finding (RARE): Bidirectional ventricular tachycardia Easy formula for administration of digoxin specific Fab (Digibind?? or DigiFab?). Remember to round up even if its 2.3 vials, give 3. [(Dig Serum Concentration(ng/mL)) x wt(kg)] / 100 = # vials

Title: Lithium Toxicity Management

Category: Toxicology

Keywords: lithium, renal failure, neurologic (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Lithium Toxicity Management Initial Therapy: 2x maintenance fluid with normal saline Hemodialysis is controversial but will remove lithium quickly Association of permanent neurologic sequelae with elevated lithium level(1) o Looks like a cerebellar stroke 1- Adityanjee. The syndrome of irreversible lithium-effectuated neurotoxicity (SILENT). Pharmacopsychiatry. 1989 Mar;22(2):81-3.

Title: Hyperthermia

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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

Title: Diagnosing Salicylate Toxicity

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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)

Title: Botulinum Toxin

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: Acetaminophen Toxicity

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: Toxic Alcohols

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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

Title: Hydrofluoric Acid (HF)

Category: Toxicology

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

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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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.

Title: Cyanide

Category: Toxicology

Keywords: cyanide, poisoning, hydroxycobalamin (PubMed Search)

Posted: 7/14/2007 by Fermin Barrueto (Updated: 12/5/2025)
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Cyanide Presents with arterialization of venous blood (venous blood draw looks like ABG) Reason: o Hemoglobin is not able to offload oxygen o CN poisons cytochrome c oxidase preventing conversion of oxygen to water and thus production of ATP Old antidote: sodium thiosulfate New antidote: hydroxycobalamin binds CN producing cyanocobalamin (Vit B12) When you give it expects a dip in pulse because of its blue color. Remember CN will give you a beautiful 100% pulse all the way to death. Lee J, et al. Potential interference by hydroxocobalamin on cooximetry hemoglobin measurements during cyanide and smoke inhalation treatments. Ann Emerg Med. 2007 Jun;49(6):802-5. Epub 2007 Jan 8.

Title: Hydrofluoric Acid Burns

Category: Toxicology

Keywords: hydrofluoric acid, burn, chemical burn, HFA, calcium gluconate (PubMed Search)

Posted: 9/5/2010 by Dan Lemkin, MS, MD (Updated: 10/2/2010)
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Hydrofluoric acid is a weak acid used primarily in industrial applications for glass etching and metal cleaning/plating. It is contained in home rust removers. Although technically a weak acid, it is very dangerous and burns can be subtle in appearance while having severe consequences.

Wilkes G. Hydrofluoric Acid Burns. Jan 28, 2010.
http://emedicine.medscape.com/article/773304-overview

2 mechanisms that cause tissue damage*
- corrosive burn from the free hydrogen ions
- chemical burn from tissue penetration of the fluoride ions
Clinical features*
- Cutaneous burns - absent findings to white-blue appearance
- Pulmonary edema
- Hypocalcemia, hyperkalemia, hypomagnesemia
Treatment*
- Decontaminate by irrigation with copious amounts of water.
- With any evidence of hypocalcemia, immediately administer 10% calcium gluconate IV.
- Cutaneous burns:
  - Apply 2.5% calcium gluconate gel to the affected area. If the proprietary gel is not available, constitute by dissolving 10% calcium gluconate solution in 3 times the volume of a water-soluble lubricant (eg, KY gel). For burns to the fingers, retain gel in a latex glove.
  - If pain persists for more than 30 minutes after application of calcium gluconate gel, further treatment is required. Subcutaneous infiltration of calcium gluconate is recommended at a dose of 0.5 mL of a 5% solution per square centimeter of surface burn extending 0.5 cm beyond the margin of involved tissue (10% calcium gluconate solution can be irritating to the tissue).
    - Do not use the chloride salt because it is an irritant and may cause tissue damage.

*Extracted from emedicine article.

Show References

Title: Octreotide for Pediatric Sulfonylurea Poisoning

Category: Toxicology

Keywords: octreotide, sulfonylurea (PubMed Search)

Posted: 4/12/2013 by Bryan Hayes, PharmD (Updated: 4/13/2013)
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Methods: A large retrospective case series evaluated 121 children under 6 years old with hypoglycemia from a sulfonylurea ingestion.

Results:

In addition to dextrose, patients who received octreotide had a median of zero hypoglycemic episodes after octreotide (compared to 2 before treatment, p < 0.0001).
Median blood glucose concentrations after receiving octreotide were also higher (62 mg/dL vs 44, p < 0.001).
Most required only 1 dose of octreotide with no reported adverse effects.

Authors' Conclusion: Octreotide administration decreases the number of hypoglycemic events and increases blood glucose concentrations in children with sulfonylurea ingestion.