Characterization of chloroquine plasma protein binding in man.

Chloroquine protein binding was determined by equilibrium dialysis of purified plasma proteins and plasma samples from 20 healthy subjects and 14 patients with rheumatoid arthritis. The mean binding was 61 +/- 9% in plasma from healthy subjects (range 46-74%) and 64 +/- 7% in plasma from rheumatoid arthritis patients (range 55-79%). Albumin and alpha 1-acid glycoprotein at physiological concentrations bound chloroquine to an approximately equal extent. Protein binding is unlikely to be an important determinant of chloroquine pharmacokinetics or response.