Drug-Drug Interaction
VALPROIC ACID/SALICYLATES
MECHANISM OF ACTION
Multiple mechanisms appear to be involved. Salicylates
may: 1. displace valproic acid from plasma protein binding sites
DISCUSSION
The interaction between salicylates and valproic acid has only
been reported clinically during concurrent administration of aspirin and
valproic acid. However, this interaction would be expected to occur with
other salicylates as well. An average increase of nearly 50% in the free
fraction of valproic acid has been reported. Valproate toxicity may occur.
CLINICAL EFFECTS
The unbound fraction of serum valproic acid concentration
may be increased resulting in toxicity.
SEVERITY LEVEL
3-Moderate Interaction: Assess the risk to the patient and
take action as needed.
PATIENT MANAGEMENT
Observe the patient for signs of valproic acid toxicity
(e.g., ataxia, drowsiness, nystagmus, tremor) during combined administration
salicylates and valproic acid. Adjust the dose of valproic acid as
necessary.
PREDISPOSING FACTORS
None determined.
REFERENCES
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