ciprofloxacin × digoxin

In 10–15 % of patients, gut flora (mainly Eubacterium lentum) metabolize part of digoxin into inactive products. Ciprofloxacin eliminates this flora – digoxin concentration may rise in these patients. Ciprofloxacin also weakly inhibits P-glycoprotein.

For ciprofloxacin courses ≥ 5 days in a digoxin-treated patient, check digoxin level and ECG at 3–5 days. Target concentration is 0.5–0.9 ng/mL in HF.