Drug General Information (ID: DDI1NLGJ9Q)
Drug Name			Trimethoprim		Drug Info		Procainamide		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiinfective Agents				Antiarrhythmic Agents
Structure

Mechanism of Trimethoprim-Procainamide Interaction (Severity Level: Moderate)
Competitive inhibition of renal tubular secretion Click to Show/Hide Mechanism Graph
Drug Name		Trimethoprim				Procainamide
Mechanism		Inhibition of the renal tubular secretion of procainamide				Procainamide
Key Mechanism Factor 1
		Factor Name		Renal tubular secretion
		Factor Description		Renal tubular secretion allows selective transfer of substances from the blood around the capillaries into the renal tubules via filtrate. Drug excretion may be reduced when two drugs compete for renal tubular secretion.
Mechanism Description		Decreased elimination of Procainamide caused by Trimethoprim mediated competitive inhibition of renal tubular secretion

Recommended Action
Management		Serum procainamide and NAPA levels should be checked during therapy, and procainamide dosage should be decreased, if necessary. Patients should be advised to promptly notify their physician if they experience drowsiness, dizziness, syncope, confusion, tremor, or palpitations.

References
1	Harron D, Brogden R "Acecaindie (N-acetylprocainamide)." Drugs 39 (1990): 720-40
2	Kosoglou T, Rocci M, Vlasses P "Trimethoprim alters the disposition of procainamide and N-acetylprocainamide." Clin Pharmacol Ther 44 (1988): 467-77
3	Vlasses P, Kosoglou T, Chase S, et al "Trimethoprim inhibition of the renal clearance of procainamide and N-acetylprocainamide." Arch Intern Med 149 (1989): 1350-3