Cardioquin and Food

Do not consume grapefruit or grapefruit juice during treatment with quiNIDine unless specifically directed otherwise by your doctor. Grapefruit and grapefruit juice can interact with quiNIDine and decrease the levels of quiNIDine in your body. If you are already consuming grapefruit products, do not increase or decrease the amount of these products in your diet without first talking to your doctor.

GENERALLY AVOID: In a small, randomized, crossover study, the administration of quinidine with grapefruit juice (compared to water) to healthy volunteers significantly prolonged the time to reach peak plasma quinidine concentrations and decreased the plasma concentrations of its major metabolite, 3-hydroxyquinidine. These changes were associated pharmacodynamically with both a delay and a reduction in the maximal effect on QTc interval. The proposed mechanism is delay of gastric emptying as well as inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits.

MANAGEMENT: Given the drug's narrow therapeutic index, patients receiving quinidine therapy should avoid the consumption of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels.