Protein binding of chloroquine enantiomers and desethylchloroquine

The protein binding of racemic chloroquine, its enantiomers and desethylchloroquine to plasma, purified human albumin, and alpha 1-acid glycoprotein (alpha 1-AGP) was determined by equilibrium dialysis. The binding was not concentration dependent. (+)-Chloroquine bound more to plasma (66.6 +/- 1.9%) and albumin (45.9 +/- 0.8%) than (-)-chloroquine (48.5 +/- 2.4% and 35.3 +/- 0.6%, respectively). These differences were statistically significant. (-)-Chloroquine bound more to alpha 1-AGP (47.5 +/- 0.7%) than (+)-chloroquine (34.5 +/- 0.5%). The binding of desethylchloroquine to alpha 1-AGP is higher than to albumin (38.9 +/- 0.9% and 21.1 +/- 0.4%, respectively.