Failure of procainamide to induce a systemic lupus erythematosus-like disease in animals

Abstract

Procainamide induces a systemic lupus erythematosus-like (SLE) syndrome in humans. Although 77% of cardiac patients receiving the drug for 6 wk or more developed LE cells and antinuclear antibodies without clinical signs of SLE, we found no evidence that it produced similar abnormalities in animals. Seven dogs received doses as high as 588 mg/kg/day for periods up to 34 wk. Hybrid NZB NZW mice which spontaneously develop an SLE-like syndrome were treated with doses as high as 2 g/kg/mouse/day in order to determine whether the drug would aggravate the disease. There was no difference in the course or life span of 59 treated hybrids from that of the 31 littermate controls. Pilot studies were done giving large amounts of procainamide to 4 white rats, 4 guinea pigs, 1 hamster, and 1 minipig for as long as 39 wk with similar negative results. To date, drug-induced lupus has not been clearly duplicated in any animal. The failure to provoke changes in other species similar to those induced in humans suggests that there may be significant differences in etiologic factors between the animal model and human SLE. Caution should be used in implying that data obtained from lupuslike animal diseases are pertinent to humans.