Recommendations:
(1) Discontinue drugs that prolong the QTc interval if the interval is > 500 milliseconds.
(2) Avoid using a drug that prolongs the QTc interval if the interval prior to starting treatment is > 450 milliseconds.
(3) Avoid using a drug that prolongs the QTc interval if the patient has significant left ventricular dysfunction.
(4) Treat hypokalemia. Keep the serum potassium > 4 mmol/L.
(5) Treat hypomagnesemia. Keep the serum magnesium > 1 mmol/L.
(6) Intravenous infusion of a drug that may prolong the QTc interval should be done slowly. Consider careful monitoring of the patient during the infusion.
(7) Reduce the dose of a drug that prolongs the QTc interval if the patient has a concurrent disease (hepatic, renal, etc) that can cause drug accumulation by reducing excretion or metabolism of the drug.
(8) If the patient is taking a drug that prolongs the QTc interval, then be careful when administering another drug that may interfere with its metabolism by the P450 system. Either avoid using both drugs at the same time or adjust drug dosages to compensate for decreased metabolism.
