What is the recommended action for dofetilide when CrCl is 20-59 mL/min?

• A. Reduce dose
• B. Avoid
• C. No adjustment
• D. Increase dose

Answer: (A)

Dofetilide is cleared mainly by the kidneys, so when renal function is reduced, the drug stays in the body longer and can raise the risk of QT prolongation and torsades de pointes. In a CrCl range of 20–59 mL/min, the risk from a standard dose is too high, so the dose needs to be reduced to match the slower clearance. This adjustment helps avoid excessive exposure while still providing the antiarrhythmic benefit. The other options would either leave the patient exposed to too much drug (increasing risk), omit necessary adjustment (unsafe), or unnecessarily withhold the drug (not required in this CrCl range). In practice, dose or dosing frequency is lowered according to the creatinine clearance, with careful ECG monitoring for QT changes.