UMEM Educational Pearls - Toxicology

Title: Valproic acid toxicity

Category: Toxicology

Keywords: Valproic acid (PubMed Search)

Posted: 10/16/2014 by Hong Kim, MD
Click here to contact Hong Kim, MD

Valproic acid (VPA) is often used to treat seizure disorder and mania as a mood stabilizer. The mechanism of action involves enhancing GABA effect by preventing its degradation and slows the recovery from inactivation of neuronal Na+ channels (blockade effect).

VPA normally undergoes beta-oxidation (same as fatty acid metabolism) in the liver mitochondria, where VPA is transported into the mitochondria by carnitine shuttle pathway.

In setting of an overdose, carnitine is depleted and VPA undergoes omega-oxidation in the cytosol, resulting in a toxic metabolite.

Elevation NH3 occurs as the toxic metabolite inhibits the carbomyl phosphate synthase I, preventing the incorporation of NH3 into the urea cycle.

Signs and symptoms of acute toxicity include:

  • GI: nausea/vomiting, hepatitis
  • CNS: sedation, respiratory depression, ataxia, seizure and coma/encephalopathy (with serum concentration VPA: > 500 mg/mL)

Laboratory abnormalities

  • Serum VPA level: signs of symptoms of toxicity does not correlate well with serum level.
  • NH3: elevated
  • Liver function test: elevated AST/ALT
  • Basic metabolic panel: hypernatremia, metabolic acidosis
  • Complete blood count: pancytopenia

Treatment: L-carnitine

  • Indication: hyperammonemia or hepatotoxicity
  • Symptomatic patients: 100 mg/kg (max 6 gm) IV (over 30 min) followed by 15 mg/kg IV Q 4 hours until normalization of NH3 or improving LFT
  • Asymptomatic patients: 100 mg/kg/day (max 3 mg) divided Q 6 hours.

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Title: Opioid Prescription Drug Abuse - The Pattern of Abuse

Category: Toxicology

Keywords: opioids, toxicology (PubMed Search)

Posted: 11/20/2014 by Fermin Barrueto (Updated: 12/5/2025)
Click here to contact Fermin Barrueto

The pattern of prescription drug abuse continues to center around semisynthetic opioids like oxycodone and hydrocodone. Federal regulations have now raised hydrocodone to a schedule II drug like oxycodone. Despite efforts, the slope for natural and semisynthetic opioids remains steep.  The ED measures of education, limit prescriptions for acute pain, minimize number of days/pills prescribed and utlize the prescription drug monitoring program are some basics that can assist you in better prescribing habits.

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Title: Opioid Prescription Drug Abuse - The Pattern of Abuse

Category: Toxicology

Keywords: opioids, toxicology (PubMed Search)

Posted: 11/20/2014 by Fermin Barrueto (Updated: 12/5/2025)
Click here to contact Fermin Barrueto

The pattern of prescription drug abuse continues to center around semisynthetic opioids like oxycodone and hydrocodone. Federal regulations have now raised hydrocodone to a schedule II drug like oxycodone. Despite efforts, the slope for natural and semisynthetic opioids remains steep.  The ED measures of education, limit prescriptions for acute pain, minimize number of days/pills prescribed and utlize the prescription drug monitoring program are some basics that can assist you in better prescribing habits.

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Title: Spider bite

Category: Toxicology

Posted: 9/5/2019 by Kathy Prybys, MD (Updated: 12/5/2025)
Click here to contact Kathy Prybys, MD

Question

A 3 year old is bitten by a spider on his right ear which is causing him intense pain, tachycardia, and muscle cramping. Identify the spider.  What is the treatment?

 

 

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