Binding of rifampicin by human plasma proteins.

The binding of rifampicin to human plasma proteins has been investigated by equilibrium dialysis. Plasma from eleven healthy subjects not taking drugs bound 87-91% of added rifampicin. Binding was lower (84-88%) in plasma from ten tuberculous patients on long-term treatment with rifampicin. Physiological concentrations of human albumin, gamma globulin and fibrinogen bound 41, 10 and 8%, respectively, of added rifampicin. Isoniazid, p-aminosalicylic acid, streptomycin and ethambutol did not significantly affect rifampicin binding to plasma proteins. [ABSTRACT FROM AUTHOR]