UMEM Educational Pearls

Category: Toxicology

Title: Drug-induced long QT

Keywords: prolonged QT, arrhythmia, adverse effect, antiarrhythmics, antibiotics, antipsychotics (PubMed Search)

Posted: 5/1/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/22/2024)
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  • Many meds cause a prolonged QT; this is due to a mutation of a gene that codes for the rapid component of the K+ rectifying current. This leads to problems with repolarization.
  • Drugs  causing prolonged QT with THERAPEUTIC doses include: antiarrhythmics (quinidine, procainamide, amiodarone, sotalol, and dofetilide)
  • Other agents that cause prolonged QT with ELEVATED serum concentrations include: antihistamines, some antibiotics and psychiatric meds (amitriptyline, cisapride, erythromycin, pimozide, thioridazine, SSRIs, trazodone, and moxifloxacin)
  • Use caution when combining medications from either, or both groups!

Other factors that are associated with prolonged QT include: bradycardia, female sex, genetics, and electrolyte abnormalities.


 Kannakeril PJ, Roden DM. Drug-Induced long QT and torsade de pointes: recent advances. Current opinions in cardiology. Jan 2007;22(1):39-43.

Horn JR, Hansten PD. Drug Interactions and QT Interval Prolongation. Pharmacy Times Dec 2004. pp66.