Double-blind placebo controlled crossover evaluation of levamisole in rheumatoid arthritis.

During levamisole therapy, 14 of 20 patients with previously unresponsive rheumatoid arthritis had significant improvement (P less than 0.05) in clinical measures of disease activity, erythrocyte sedimentation rate, and rheumatoid factor titer in a 32-week double-blind placebo controlled crossover trial. Levamisole was shown to alter antibody responses to tetanus and typhoid antigens, lymphocyte blastogenesis to phytohemagglutinins, and the number of null cells in peripheral blood. Agranulocytosis and rash resulted in discontinuation of the drug in one patient in each group. Though clearly effective, routine use of levamisole as a disease suppressant in rheumatoid arthritis must await more complete clarification of its association with agranulocytosis.