<li>Exercise caution with grapefruit products. Grapefruit may delay the absorption of quinidine, and inhibit its metabolism through CYP3A4.</li>
<li>Exercise caution with St. John's Wort.</li>
<li>Take separate from antacids. Antacids may reduce the absorption of quinidine.</li>
<li>Take with or without food. Taking quinidine with food may slow its absorption.</li>