VPA toxicity

Q: Patients with Valproic acid (VPA) toxicity develop all of the following EXCEPT? (select one)

A) hyponatremia

B) hyperosmolality

C) hypocalcemia

D) anion gap acidosis

E) elevated osmolal gap

Answer: A

Knowing how to treat drug overdose is essential in ICU. This question aims to identify the lab evidence of valproic acid overdose. The use of valproic acid is on the rise as an anti-delirium agent in ICU. 

VPA is a high-sodium salt compound. It contains 13.8 mg sodium per 100 mg of VPA. Toxicity results in significant hypernatremia. It contains osmotically-active acids, resulting in osmolal and anion gaps. Hypocalcemia develops when calcium binds anionic VPA metabolites.

Treatment is usually supportive. Hemodialysis can be carried out in extreme cases.

#toxicity

References:

1. Anderson, GO, Ritland, S. Life threatening intoxication with sodium valproate. Clin Toxicol 1995; 33:279.

2. Khoo SH, Leyland MJ. Cerebral edema following acute sodium valproate overdose. J Toxicol Clin Toxicol 1992; 30:209.

3. Mortensen PB, Hansen HE, Pedersen B, et al. Acute valproate intoxication: biochemical investigations and hemodialysis treatment. Int J Clin Pharmacol Ther Toxicol 1983; 21:64.