Hydroxychloroquine can increase the level of which cardiac medication?

• A. Digoxin
• B. Amiodarone
• C. Lidocaine
• D. Metoprolol

Answer: (A)

The key idea is how drug interactions via transporter proteins can raise levels of a drug with a narrow therapeutic window. Hydroxychloroquine can inhibit intestinal P-glycoprotein, which normally pumps digoxin back into the gut. With this transporter inhibited, more digoxin is absorbed, and renal clearance may also be affected, leading to higher serum levels. Because digoxin toxicity is a real risk, this interaction is clinically important and calls for monitoring digoxin levels, watching renal function and electrolytes, and adjusting dose if needed. The other listed cardiac meds aren’t typically known for their levels being increased by hydroxychloroquine in standard practice, so the digoxin interaction is the most relevant example here.