Drug General Information (ID: DDI13T7H5Q)
Drug Name			Phenytoin		Drug Info		Sulfamethoxazole		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anticonvulsants				Antiinfective Agents
Structure

Mechanism of Phenytoin-Sulfamethoxazole Interaction (Severity Level: Minor)
Competitive binding of plasma proteins Click to Show/Hide Mechanism Graph
Drug Name		Phenytoin				Sulfamethoxazole
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 Sulfamethoxazole and Phenytoin due to competitive binding of plasma proteins

References
1	Dasgupta A, Dennen DA, Dean R, McLawhon RW "Displacement of phenytoin from serum protein carriers by antibiotics: studies with ceftriaxone, nafcillin, and sulfamethoxazole." Clin Chem 37 (1991): 98-100. [PMID: 1988217]
2	Hansen JM, Kampmann JP, Siersback-Nielsen K, et al. "The effect of different sulfonamides on phenytoin metabolism in man." Acta Med Scand Suppl 624 (1979): 106-10. [PMID: 284708]
3	Lumholtz B, Siersbaek-Nielsen K, Skovsted L, Kampmann J, Hansen JM "Sulfamethizole-induced inhibition of diphenylhydantoin, tolbutamide, and warfarin metabolism." Clin Pharmacol Ther 17 (1975): 731-4. [PMID: 1139863]