<p><strong>Digoxin</strong>: Concomitant use of Trospium and digoxin did not affect the pharmacokinetics of either drug.<br />
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<strong>Drugs Eliminated by Active Tubular Secretion</strong>: Although demonstrated in a drug-drug interaction study not to affect the pharmacokinetics of digoxin, Trospium has the potential for pharmacokinetic interactions with other drugs that are eliminated by active tubular secretion (e.g., procainamide, pancuronium, morphine, vancomycin, and tenofovir). Coadministration of Trospium with these drugs may increase the serum concentration of Trospium and/or the coadministered drug due to competition for this elimination pathway. Careful patient monitoring is recommended in patients receiving such drugs.<br />
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<strong>Antimuscarinic Agents</strong>: The concomitant use of Trospium with other antimuscarinic agents that produce dry mouth, constipation, and other anticholinergic pharmacological effects may increase the frequency and/or severity of such effects. Trospium may potentially alter the absorption of some concomitantly administered drugs due to anticholinergic effects on gastrointestinal motility.<br />
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<strong>Metformin</strong>: Co-administration of 500 mg metformin immediate release tablets twice daily with Trospium 60 mg extended release reduced the steady-state systemic exposure of trospium by approximately 29% for mean AUC0-24&nbsp;and by 34% for mean Cmax.</p>