Drug General Information (ID: DDIVPXEJC4)
Drug Name			Valproic acid		Drug Info		Ethotoin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anticonvulsants				Anticonvulsants
Structure

Mechanism of Valproic acid-Ethotoin Interaction (Severity Level: Moderate)
Competitive binding of plasma proteins Click to Show/Hide Mechanism Graph
Drug Name		Valproic acid				Ethotoin
Mechanism		Competition for plasma protein binding sites				Competition for plasma protein binding sites
Key Mechanism Factor 1
		Factor Name		Plasma protein binding
		Factor Description		Plasma protein binding refers to the degree of binding of a drug to proteins in the blood, and the lower the degree of binding, the more efficiently the drug can cross cell membranes or diffuse. Plasma protein binding alters the distribution and therapeutic characteristics of the drugs.
Mechanism Description		Increased plasma concentration of Ethotoin and Valproic acid due to competitive binding of plasma proteins

Recommended Action
Management		Patients on combination therapy should be closely monitored for clinical and laboratory evidence of altered effects. Patients should be advised to notify their physician if they experience symptoms of toxicity (e.g., drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia).

References
1	Henriksen O, Johannessen SI "Clinical and pharmacokinetic observations on sodium valproate: a 5-year follow-up study in 100 children with epilepsy." Acta Neurol Scand 65 (1982): 504-23. [PMID: 6810648]
2	Riva R, Albani F, Contin M, Perucca E, Ambrosetto G, Gobbi G "Time-dependent interaction between phenytoin and valproic acid." Neurology 35 (1985): 510-5. [PMID: 3920548]