Drug Interactions between Quinidex Extentabs and sucralfate

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.

ADJUST DOSING INTERVAL: The administration of sucralfate with enteral nutrition may result in precipitation and the formation of bezoars that may obstruct feeding tubes. The proposed mechanism is the formation of an insoluble aluminum-protein complex between the aluminum in the sucralfate and the protein in the enteral feeding. In addition, sucralfate may not become activated due to the alkaline pH of enteral nutrition products.

MANAGEMENT: Some experts recommend separating the sucralfate doses from enteral feedings by at least 1 hour. Alternatively, consideration may be given to proton pump inhibitors or H2 antagonists.