Clinical response in relation to dose of penicillamine in the treatment of rheumatoid arthritis.

Large differences exist in the maintenance doses of penicillamine that clinicians regard as effective and safe in rheumatoid arthritis. From a study of the results of several clinical trials and surveys it is evident that, while some of the differences of regimen result from true individual variation in the response of patients to particular doses, others derive from the variety of criteria of efficacy and toxicity used by different clinicians. No regimen has proved clinically curative or has consistently halted radiographic deterioration. In most surveys regardless of dose at least one-third of the patients stop treatment because of toxicity or inefficacy. Placebo-controlled trials have been of short (less than 1 year) duration and longer term surveys have not included a placebo group so that the therapeutic contribution of penicillamine therapy in the long-term treatment of the generality of rheumatoid patients cannot be estimated accurately. Good control of the disease has been recorded in numbers of patients for five years or more at different doses of penicillamine, most clinicians being prepared to raise or lower doses according to response. Under the prevailing circumstances it may be impossible to complete an adequately controlled long term dose/response study of penicillamine in rheumatoid arthritis.