Procainamide organic cation transport

PROCAINAMIDE ANTIBIOTICS - TRIMETHOPRIM Procainamide levels are t by trimethoprim Trimethoprim is a potent inhibitor of organic cation transport in the kidney, and elimination of procainamide is impaired Watch for signs of procainamide toxicity 1 the dose of procainamide, particularly in the elderly... 

CIMETIDINE, RANITIDINE ANTIARRHYTHMICS-AMIODARONE, FLECAINIDE, MEXILETINE, PROCAINAMIDE, PROPAFENONE Likely t plasma concentrations of these antiarrhythmics and risk of adverse effects Cimetidine inhibits CYP2D6-mediated metabolism of flecainide, mexiletine, procainamide and propafenone. Ranitidine is a much weaker CYP2D6 inhibitor. Cimetidine is a potent inhibitor of organic cation transport in the kidney, and the elimination of procainamide is impaired Monitor PR and BP at least weekly until stable. Warn patients to report symptoms of hypotension (lightheadedness, dizziness on standing, etc.). Consider alternative acid suppression therapy... 

The OAT family of transporters can be inhibited by probenecid. If a substrate of this family of transporters, such as penicillin, is administered concomitantly with probenecid, the dmg can have decreased renal secretion, with a resulting increase in the plasma penicillin concentration. Cimetidine is an inhibitor of members of the OAT, organic cation transporter (OCT) and OATP families of transporters This inhibition has been shown to result in a decrease in the renal excretion of substrates such as procainamide and levofloxacin, resulting in increased plasma concentrations of these dmgs. 

---