Differences between blacks and whites in plasma protein binding of drugs.
OBJECTIVE
Disopyramide and salicylic acid were used as model compounds to characterize racial differences in binding of drugs by alpha 1-acid glycoprotein (AGP) and albumin, respectively. Drug-free plasma was collected from 29 healthy volunteers (15 white, 14 black). Disopyramide and salicylic acid unbound fractions (fu) in plasma were determined by equilibrium dialysis using 14C-disopyramide and 14C-salicylic acid.


RESULTS
Disopyramide unbound fractions were significantly higher in blacks than whites (0.131 vs 0.113) as were salicylic acid unbound fractions (0.053 vs 0.048). When unbound fractions were corrected for AGP and albumin concentration, racial differences were no longer present.


CONCLUSIONS
Many drugs which bind to AGP and/or albumin may exhibit racial differences in unbound fractions. However, these differences are likely explained by differences in protein concentrations rather than differences in the number of binding sites on the protein or racial differences in affinity of the protein for drugs.
Johnson
J A
JA
Department of Clinical Pharmacy, University of Tennessee-Memphis 38163, USA.
Livingston
T N
TN
D000328:Adult; D014151:Anti-Anxiety Agents / Q000097:blood; D000889:Anti-Arrhythmia Agents / Q000097:blood; D000925:Anticoagulants / Q000097:blood; D044383:Black People; D001798:Blood Proteins / Q000378:metabolism*; D003975:Diazepam / Q000097:blood; D004206:Disopyramide / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D009961:Orosomucoid / Q000378:metabolism; D011485:Protein Binding; D012459:Salicylates / Q000097:blood; D020156:Salicylic Acid; D012709:Serum Albumin / Q000378:metabolism; D014859:Warfarin / Q000097:blood; D044465:White People
D014151:Anti-Anxiety Agents; D000889:Anti-Arrhythmia Agents; D000925:Anticoagulants; D001798:Blood Proteins; D009961:Orosomucoid; D012459:Salicylates; D012709:Serum Albumin; D014859:Warfarin; D004206:Disopyramide; D020156:Salicylic Acid; D003975:Diazepam