Neurologic complications of FK 506.
F K 506 is used ,increasingly to prevent rejection i.n ~rgan transplantation.Both expenmental ' -3 and chmcal4.5 studies suggest that FK 506 is a more potent immunosuppressive agent than cyclosporine (Cy Al, and there are indications that FK 506 may also be les's toxic.b The advent of any new agent such as FK 506 promises more effective immunosuppression.but also gives rise to the need for further study of potential toxic side effects.Indeed.a report by Reyes et al 7 of two patients who developed speech dysfunction while on FK 506 suggests that this agent may under certain circumstances produce adverse _::....effects on the nervous system.Thus.more information is needed about potential nervous system disturbances that may occur in association with the clinical use of FK 506 in transplant patients.We carried out this study to identify the spectrum and frequency of neurologic disturbances that may occur in transplant patients receiving FK 506. PATIENTS AND METHODSData regarding the toxic effects of FK 506 on the nervous system were obtained from three major patient sources: group I consisted of those patients in the general transplant population who were seen routinely for neurologic events: group 2 comprised a prospective study of 294 consecutive adult recipients: and group 3 resulted from surveillance of outpatients for possible long-term complications of FK 506.The details of these patient groups are given below.