Table 1

Summary of intravenous quinidine doses administered and risk factors for the development of torsades de pointesa

ParameterResult for patient no.:
123456
Loading dose (mg/kg)6201010010
Infusion rate (mg/kg/h)0.020.020.020.020.020.02
Total dose received (mg/kg)7.020.110.110.41.510.2
Duration of therapy (h)4871122759
Baseline QTc (ms)465433602498428451
Maximum QTc (ms)531543704550450473
TdPNoNoYesYesNoNo
Advanced age (≥65 yr)Yes (73 yr)NoNoNoNoNo
Sex (female)YesNoYesYesYesNo
Hypokalemia (K+ < 3.5 meq/liter)NoYesYesNoYesNo
Hypomagnesemia (Mg2+ < 1.8 mg/dl)NoNoNoYesNoNo
Hypocalcemia (Ca2+ < 7.6 mg/dl)YesYesYesNoNoNo
History of left ventricular dysfunctionNoNoNoYesNoNo
Acute liver dysfunctionYesNoYesYesNoYes
Concomitant administration of QTc-prolonging medicationNoNoNoYesNoNo
Total no. of risk factors for drug-induced TdP324520
  • a Risk factors for torsades de pointes (TdP) included age of ≥65 years, female sex, hypokalemia at the time of quinidine administration, hypomagnesemia at the time of quinidine administration, hypocalcemia at the time of quinidine administration, documented history of left ventricular dysfunction, concomitant administration of QT interval-prolonging medications, and baseline QTc interval of ≥470 ms in males and ≥480 ms in females.