Propafenone Hydrochloride Ketoconazole
ModeratePropafenone's levels in the blood can go up when it is taken with ketoconazole. Ketoconazole works by blocking CYP3A4, the liver enzyme that normally breaks propafenone down. Other medicines that block the same enzyme, such as ritonavir, saquinavir, erythromycin and even grapefruit juice, can do the same. Medicines that block CYP2D6 (for example desipramine, paroxetine, ritonavir and sertraline) or CYP1A2 (for example amiodarone) can also push propafenone levels higher.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.