Table 1.

Summary of intravenous quinidine doses administered and risk factors for the development of torsades de pointes^a

Parameter	Result for patient no.:
	1	2	3	4	5	6
Loading dose (mg/kg)	6	20	10	10	0	10
Infusion rate (mg/kg/h)	0.02	0.02	0.02	0.02	0.02	0.02
Total dose received (mg/kg)	7.0	20.1	10.1	10.4	1.5	10.2
Duration of therapy (h)	48	7	11	22	75	9
Baseline QTc (ms)	465	433	602	498	428	451
Maximum QTc (ms)	531	543	704	550	450	473
TdP	No	No	Yes	Yes	No	No
Advanced age (≥65 yr)	Yes (73 yr)	No	No	No	No	No
Sex (female)	Yes	No	Yes	Yes	Yes	No
Hypokalemia (K+ < 3.5 meq/liter)	No	Yes	Yes	No	Yes	No
Hypomagnesemia (Mg2+ < 1.8 mg/dl)	No	No	No	Yes	No	No
Hypocalcemia (Ca2+ < 7.6 mg/dl)	Yes	Yes	Yes	No	No	No
History of left ventricular dysfunction	No	No	No	Yes	No	No
Acute liver dysfunction	Yes	No	Yes	Yes	No	Yes
Concomitant administration of QTc-prolonging medication	No	No	No	Yes	No	No
Total no. of risk factors for drug-induced TdP	3	2	4	5	2	0

^aRisk 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.