Long-term clinical toxicity studies with clofazimine (B663) in leprosy.

Fifty-one leprosy patients receiving long-term clofazimine have undergone systematic clinical laboratory testing in a search for any toxicity secondary to the drug. In approximately 220 patient-years of observation and in analyzing approximately 40,000 test results, no statistically significant changes in the direction of abnormality have been observed in SGOT, thymol turbidity, serum globulins, uric acid, alkaline phosphatase, white blood cell count or differential, hematocrit, hemoglobin, BUN, serum creatinine, serum cholesterol, serum albumin, serum potassium, serum calcium, stool for occult blood, routine urinalysis, or reticulocyte count. Statistically significant changes toward abnormality were found in fasting blood sugar and total serum bilirubin. These statistically significant changes in the direction of abnormality were of a small magnitude, were not associated with related clinical signs or symptoms, and do not seem to be of major clinical significance. Despite the accumulation of relatively massive amounts of the drug in various tissues, clofazimine appears remarkably free of serious or life-threatening toxicity clinically. Although the skin and gastrointestinal side effects of clofazimine limit its usefulness, on the evidence to date, its advantages outweigh its disadvantages in those leprosy patients for whom it is indicated.