Drug Interactions between losartan and Vantin

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of cefpodoxime proxetil tablets. Following a 200 mg dose taken with food, the extent of absorption (mean AUC) was 21% to 33% higher and the mean peak plasma concentration (Cmax) 19% higher than under fasting conditions. Time to peak concentration (Tmax) was not significantly different between fed and fasted states. On the contrary, when a 200 mg dose of the suspension was taken with food, the mean AUC and Cmax were not significantly different than those under fasting conditions, although the rate of absorption was slower with food (48% increase in Tmax ).

MANAGEMENT: To ensure maximal oral absorption, cefpodoxime proxetil tablets should be administered with or immediately after a meal.

GENERALLY AVOID: Moderate-to-high dietary intake of potassium, especially salt substitutes, may increase the risk of hyperkalemia in some patients who are using angiotensin II receptor blockers (ARBs). ARBs can promote hyperkalemia through inhibition of angiotensin II-induced aldosterone secretion. Patients with diabetes, heart failure, dehydration, or renal insufficiency have a greater risk of developing hyperkalemia.

MANAGEMENT: Patients should receive dietary counseling and be advised to not use potassium-containing salt substitutes or over-the-counter potassium supplements without consulting their physician. If salt substitutes are used concurrently, regular monitoring of serum potassium levels is recommended. Patients should also be advised to seek medical attention if they experience symptoms of hyperkalemia such as weakness, irregular heartbeat, confusion, tingling of the extremities, or feelings of heaviness in the legs.

MONITOR: Grapefruit juice may modestly decrease and delay the conversion of losartan to its active metabolite, E3174. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The clinical significance is unknown. Moreover, pharmacokinetic alterations associated with interactions involving grapefruit juice are often subject to a high degree of interpatient variability.

MANAGEMENT: Patients who regularly consume grapefruits and grapefruit juice should be monitored for altered efficacy of losartan. Grapefruits and grapefruit juice should be avoided if an interaction is suspected. Orange juice is not expected to interact.