Lack of citalopram effect on oral digoxin pharmacokinetics

The effect of chronic administration of citalopram on the single oral dose pharmacokinetics of digoxin was evaluated in 11 healthy adult subjects in a n open, one-way crossover study. Subjects received 1 mg digoxin on day 1. S erial blood samples and total urine were collected over 192 hours, followed by an 11-day washout period. On days 22 through 50, subjects received 40 m g citalopram once daily. On day 43, a single dose of 1 mg digoxin was coadm inistered; again, serial blood samples and total urine were collected over 192 hours after the digoxin dose. There were no statistically significant d ifferences in any of the digoxin pharmacokinetic parameters (AUC(0-->24), A UC(0-->infinity), C-max, t(max), t(1/2), CL/F: CLrenal, and Ae(0-->infinity )), and the 90% confidence intervals for treatment differences for the para meters (except for t(max)) were all within 80% to 125%. Concomitant digoxin administration did not significantly affect citalopram pharmacokinetics. T he treatment was well tolerated by all subjects; no serious adverse events and no clinically significant ECG changes were observed. These data suggest that it is unlikely that concomitantly administered citalopram would have any significant effect on serum digoxin concentrations in patients who are receiving chronic digoxin therapy Journal of Clinical Pharmacology; 2001;41 :340-346 (C) 2001 the American College of Clinical Pharmacology.