Dofetilide and Ketoconazole

Desk tier: Avoid together

Mechanism: combined QT load (additive QT prolongation / TdP)

“The concomitant use of verapamil or the cation transport system inhibitors cimetidine, trimethoprim (alone or in combination with sulfamethoxazole), or ketoconazole with TIKOSYN is contraindicated”

Tikosyn (dofetilide), section CONTRAINDICATIONS. DailyMed label

Why this grade

Tikosyn (dofetilide) label, Contraindications

The Tikosyn (dofetilide) label lists this combination under Contraindications. CONTRAINDICATIONS: "The concomitant use of verapamil or the cation transport system inhibitors cimetidine, trimethoprim (alone or in combination with sulfamethoxazole), or ketoconazole with TIKOSYN is contraindicated" Named in the label: "ketoconazole" Retrieved from DailyMed 2026-10-12.

Open source

Prescribing Information

CredibleMeds-class QT plus methadone / citalopram / ondansetron labels. Not a QTc.

Open source

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All pairs for Dofetilide · Ketoconazole

Educational reference only. Not FDA-cleared. The Prescribing Information governs.

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