[Determination of unbound concentration of drug in drug-human serum albumin mixture by high performance frontal analysis].
A high performance frontal analysis(HPFA) method was developed to determine the unbound concentration of drugs in drug-human serum albumin (HSA) mixture under binding equilibrium. The sample was injected directly onto an internal-surface reversed-phase silica column (ISRP). The mobile phase was 67 mmol/L phosphate buffer (pH 7.4, I = 0.17 mol/L). When a large volume of sample solution under drug-HSA binding equilibrium was directly injected, the drug was eluted as a trapezoidal peak with a plateau, and the drug concentration in this region was the same as that of the unbound drug in the sample solution. The eluate of plateau region was collected and a small volume was injected onto a reversed-phase HPLC column. This HPFA-HPLC method was employed in the determination of unbound concentration in both ketoprofen (KP)-HSA and cefoperazone (CP)-HSA mixtures. The unbound concentrations of drugs obtained by using HPFA-HPLC were compared with those determined with ultrafiltration-HPLC. The effects of sample volume and flow rate of mobile phase on the plateau formation were investigated. It was found that the minimum injection volume to achieve a trapezoidal peak varied with drugs. The flow rate showed no effect on the trapezoidal peak formation. The unbound concentrations of KP and CP obtained were about the same by using HPFA-HPLC or ultrafiltration-HPLC and precisions were similar for both methods.
Qiao
M X
MX
Shenyang Pharmaceutical University, Shenyang 110016, China.
Guo
X J
XJ
Li
F M
FM
D002438:Cefoperazone / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007660:Ketoprofen / Q000097:blood; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D014462:Ultrafiltration
D011506:Proteins; D012709:Serum Albumin; D002438:Cefoperazone; D007660:Ketoprofen