Experience with penicillamine in the treatment of cystinuria.

Some patients with cystinuria can be treated with a high fluid intake, but some continue to form stones and require penicillamine treatment. The incidence of complications particularly proteinuria is reviewed. Reduction of penicillamine dosage is desirable to prevent complications, but this is accompanied by an increase of cystine excretion. The effective dosage has therefore to be higher than that used in rheumatoid arthritis. We have now measured penicillamine concentrations in these patients by gas chromatography. The protein bound fraction is greater than 80% of the total, and may represent a reservoir of drug for therapeutic action.