A pressure ultrafiltration method for serum free drug determination. Comparison with equilibrium dialysis using normal and uraemic sera
Tiula, E.
Methods and Findings in Experimental and Clinical Pharmacology 6(1): 51-55
1984
ISSN/ISBN: 0379-0355 PMID: 6717171 Document Number: 241300
The clinical methods most frequently used for serum free drug determinations are equilibrium dialysis and ultrafiltration. Both methods were usually considered equal when comparisons were made on normal human sera. A reliable and rapid method for serum free drug determinations, especially for disease states where there is an increased free fraction was developed. This modification of the pressure ultrafiltration method proved to meet these demands. The method was tested in vitro by adding radiolabeled phenytoin in different concentrations to normal and uremic sera. The within-run and between-run variation coefficients were both under 5%. In comparison with equilibrium dialysis the values obtained by the ultrafiltration method were 0.65% lower (P < 0.001, Student's paired t-test) in normal and 0.37% lower (non-significant) in uremic sera. There are theoretical grounds to presume that the results obtained by means of the pressure ultrafiltration method would better reflect the real values than those obtained by means of equilibrium dialysis.