It has been reported that Grapefruit and grapefruit juice may interact with Tikosyn (dofetilide) and lead to potentially dangerous effects.
Grapefruit segments or an extract of unprocessed grapefruit cause drug interactions to a similar extent. Seville oranges (used in some marmalades, but not in commercial orange juice), purnmelos and tangelos may also cause similar interactions. Based on metabolic pathways of drugs that interact with grapefruit, we can predict other drugs that may have significant interactions with grapefruit. Grapefruit inhibits metabolism of oral medications by cytochrome P450 3A4 isoenzymes in the intestinal wall, decreasing the metabolism of affected drugs and increasing the amount of drug entering the bloodstream. Increased drug levels can cause more side effects and/or toxicity. The effect of grapefruit on intestinal enzymes is irreversible and persists for up to 72 hours after grapefruit consumption, until more of the drug metabolizing enzymes are produced. Grapefruit is also an inhibitor of p-glycoprotein, an efflux pump in intestinal cell wall enterocytes that actively secretes absorbed drug back into the gut lumen. Organic anion transporting polypeptide (OATP) is another transporter system affected by grapefruit. Drugs that are significantly handled by p-glycoprotein or OATP may have decreased absorption when taken with grapefruit, possibly leading to loss of efficacy.
Discuss the use of grapefruit products with your doctor, who may have prescribed the med.
Take care, best wishes!
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