Decreased quinidine plasma protein binding during hemodialysis.
Quinidine binding to serum proteins was quantitated in 10 regularly dialyzed patients with end-stage renal disease, both under baseline conditions and after heparin during a single hemodialysis. Quinidine binding was determined in vitro, after the addition of 2 micrograms/ml quinidine sulfate, by ultrafiltration combined with spectrophotofluorometry. The baseline percent unbound quinidine concentration in our patients was 6.5 +/- 2.3% (mean +/- SD), a value lower than in normal subjects (9.9 +/- 3.0%, n = 18, p less than 0.005). Binding correlated with both serum albumin (r = 0.72, p less than 0.02) and free fatty acid (r = 0.65, p less than 0.05) concentrations. After heparin there was a rise in percent unbound quinidine (12.2 +/- 5.6%, p less than 0.025) and in free fatty acid concentration (1111 +/- 1202 microEq/l, p = 0.004) in each subject. After heparin the relationship between quinidine binding and free fatty acid concentration was again evident (r = 0.97, p less than 0.001). Dynamic changes in the levels of free quinidine, as well as other drugs during hemodialysis, may require adjustments to avoid toxicity and adverse interactions.
D001798:Blood Proteins / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood; D011485:Protein Binding / Q000187:drug effects; D011802:Quinidine / Q000097:blood*; D006435:Renal Dialysis
D001798:Blood Proteins; D005230:Fatty Acids, Nonesterified; D006493:Heparin; D011802:Quinidine