Dose, plasma concentration and response relationships of D-penicillamine in patients with rheumatoid arthritis.

Plasma concentrations were measured in 10 patients with rheumatoid arthritis taking 250 mg, 500 mg and 750 mg of D-penicillamine daily. A disproportionate rise in the dose adjusted area under the plasma concentration vs time curve suggested dose dependent kinetics for D-penicillamine. Marked interindividual variability was seen with pharmacokinetic parameters and no correlations were observed between side effects or response and plasma concentrations of reduced D-penicillamine.