Summary

Lansoprazole may increase digoxin plasma concentrations by reducing gastric acid production, which can enhance digoxin absorption. This interaction is generally considered mild to moderate but requires monitoring of digoxin levels and cardiac function.

Introduction

Lansoprazole is a proton pump inhibitor (PPI) commonly prescribed for gastroesophageal reflux disease (GERD), peptic ulcers, and Helicobacter pylori eradication. It works by irreversibly blocking the hydrogen-potassium ATPase enzyme in gastric parietal cells, significantly reducing stomach acid production. Digoxin is a cardiac glycoside derived from the foxglove plant, primarily used to treat heart failure and certain arrhythmias like atrial fibrillation. It works by inhibiting the sodium-potassium ATPase pump, leading to increased intracellular calcium and enhanced cardiac contractility.

Mechanism of Interaction

The interaction between lansoprazole and digoxin occurs through altered gastrointestinal absorption. Lansoprazole's potent acid suppression increases gastric pH, creating a more alkaline environment in the stomach. Digoxin absorption can be enhanced in less acidic conditions, as the reduced acidity may improve the dissolution and bioavailability of digoxin tablets. Additionally, the altered gastric environment may affect the activity of gut bacteria that can metabolize digoxin, potentially leading to increased systemic exposure to the active drug.

Risks and Symptoms

The primary clinical risk of this interaction is potential digoxin toxicity due to increased plasma concentrations. Symptoms of digoxin toxicity include nausea, vomiting, loss of appetite, visual disturbances (yellow-green halos), confusion, and cardiac arrhythmias such as bradycardia, heart block, or ventricular arrhythmias. Elderly patients and those with renal impairment are at higher risk due to reduced digoxin clearance. The interaction significance is generally considered mild to moderate, but individual patient factors can increase the clinical relevance.

Management and Precautions

When lansoprazole and digoxin are used concurrently, monitor digoxin serum levels more frequently, especially when initiating, discontinuing, or changing the dose of lansoprazole. Baseline digoxin levels should be established before starting lansoprazole therapy. Consider checking digoxin levels 1-2 weeks after lansoprazole initiation or dose changes. Monitor patients for signs and symptoms of digoxin toxicity, including cardiac rhythm abnormalities, gastrointestinal symptoms, and neurological changes. Regular assessment of renal function, electrolyte levels (particularly potassium and magnesium), and cardiac function is recommended. If digoxin toxicity occurs, consider dose reduction or temporary discontinuation while maintaining appropriate acid suppression therapy.

Lansoprazole interactions with food and lifestyle

Lansoprazole should be taken on an empty stomach, preferably 30-60 minutes before meals, as food can significantly reduce its absorption and effectiveness. Alcohol consumption should be limited or avoided while taking lansoprazole, as alcohol can increase stomach acid production and counteract the medication's acid-reducing effects. Additionally, alcohol may worsen gastroesophageal reflux disease (GERD) symptoms that lansoprazole is intended to treat.

Digoxin interactions with food and lifestyle

Digoxin has several important food and lifestyle interactions that patients should be aware of. High-fiber foods, including bran cereals and fiber supplements, can significantly reduce digoxin absorption and should be taken at least 2 hours apart from digoxin doses. St. John's wort, an herbal supplement, can decrease digoxin levels and reduce its effectiveness, so concurrent use should be avoided. Alcohol consumption can affect digoxin levels and increase the risk of side effects, particularly heart rhythm abnormalities. Patients should limit alcohol intake and discuss any alcohol use with their healthcare provider. Additionally, maintaining consistent dietary habits is important, as sudden changes in fiber intake or meal timing can affect digoxin absorption and blood levels. Patients should also be cautious with salt substitutes containing potassium, as changes in potassium levels can affect digoxin's effectiveness and safety.