Alterations of auditory evoked potentials during the course of chloroquine treatment.

Chloroquine phosphate is now used extensively in the treatment of active rheumatoid arthritis and in some collagen diseases. The ototoxic potential of this drug during long term use was assessed in 74 patients. At a time when pure tone and speech audiometry failed to demonstrate any hearing change, brainstem audiometry became abnormal in 13 patients. Abnormalities disappeared if chloroquine was withdrawn. Pathogenesis will be discussed on the basis of data obtained from animal experiments.