Procainamide-induced lupus erythematosus. Clinical and laboratory observations

Procainamide hydrochloride in conventional doses can elicit a syndrome closely resembling systemic lupus erythematosus (SLE). The most frequent symptoms are polyarthralgia, myalgia, fever and pleurisy. Renal disease is notably absent. Conventional serologic tests give results similar to those in SLE except that serum complement is not decreased. A photodynamically induced complex between deoxyribonucleic acid (DNA) and procainamide is described which may be useful as a pathogenetic model. By a globulin precipitation method, patients with procainamide-induced lupus appear to have anti-body to denatured DNA and nucleohistone, but in contrast to idiopathic SLE, have little or no antibody to native DNA.