Effect of quinine on plasma digoxin concentration and renal digoxin clearance.
In order to explore the digoxin-quinine interaction, digoxin steady state pharmacokinetics was studied before and during quinine coadministration in seven healthy subjects. Quinine (250 mg/day) increased mean plasma digoxin concentration from 0.64 +/- 0.12 to 0.80 +/- 0.18 ng/ml (p less than 0.05) within one week. Urinary digoxin recovery rose from 154.0 +/- 18.8 to 181.5 +/- 22.6 micrograms/24 h (p less than 0.01), whereas renal digoxin clearance was unaltered in the presence of quinine (181.5 +/- 24.2 vs. 174.1 +/- 26.5 ml/min). An increase in quinine dose (to 750 mg/day) caused further increments in plasma digoxin levels, whereas renal digoxin clearance remained unchanged. Quinine elevates plasma digoxin concentrations in a stepwise fashion probably due to an impairment of extrarenal digoxin clearance.
D000328:Adult; D004077:Digoxin / Q000097:blood / Q000378:metabolism*; D004347:Drug Interactions; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011803:Quinine / Q000494:pharmacology*
D004077:Digoxin; D011803:Quinine