A method of comparing the toxicities of disease suppressive agents: possible application to a comparison between D-penicillamine and chloroquine.

A general method for calculating incidences of the more common adverse reactions during long-term therapy with disease suppressive agents is presented. With D-penicillamine treatment, the incidence of proteinuria rises during 6-12 months and then declines, but with aurothiomalate treatment the incidence of proteinuria and rash progressively decline. Low-dose chloroquine treatment was associated with a much lower withdrawal rate due to adverse reactions compared to D-penicillamine. However, the efficacy at mean doses of chloroquine less than 250 mg day-1 has not been formally evaluated. A formal, well-controlled trial comparing D-penicillamine, at current dosage, and of chloroquine, at low dosage, seems warranted in order to place the usefulness of D-penicillamine in perspective.