Voriconazole interaction with class: Analgesics

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Interaction with Methysergide

Avoid combination
QT risk: Voriconazole Methysergide

Effect: Voriconazole may increase the plasma concentrations of ergot derivates (e.g. methyserigide). 

Clinical management: Avoid concurrent use of voriconazole and ergot derivates. If concomitant use is required, carefully monitor for increased risk of ergotism (excessive vasoconstriction in the extremities, convulsions, GI/CNS effects).

Probable mechanism: Inhibition of the cytochrome P450 3A4-mediated biotransformation by voriconazole.

Summary: Although not studied clinically, coadministration of the CYP3A4 inhibitor voriconazole and ergot derivates (dihydroergotamine, ergotamine, ergoloid mesylates, ergometrine, methylergometrine, methysergide) may result in increased plasma concentrations of the ergot derivate. Hence, combination of triazoles known to strongly inhibit CYP3A4 (itraconazole, posaconazole and voriconazole) and ergot derivates is contraindicated (unlike the moderate CYP3A4 inhibitor fluconazole).


QT effect

Voriconazole: Conditional QT risk

Substantial evidence reports that this drug causes QT prolongation and has a risk of TdP, but only under certain known conditions (e.g. excessive dose, drug interaction, etc.).


Methysergide: QT risk not available