Identifying and Characterizing Toxic Degradation Products in Cellulose Acetate Dialyzers
A.D. Lucas, J.A. Kalson, J.C. Hutter and R.R. Wallis, CDRH, FDA, Rockville, MD 20852
In September 1996, seven patients at Hospital A suffered headache, vision and hearing loss 7-24 h after hemodialysis treatment. Twelve-year-old dialysis modules were identified as a common link between these patients, with degradation postulated as the probable cause of this incident. Cellulose acetate (CA) dialysis membranes were retrieved and tested for degradation products. To verify the suspected cause of this incident, a series of in vitro, chemical and in vivo tests of various CA degradation products was conducted. Based on the toxicity of the material preparations to the cells, animal tests were performed. Rabbits displayed "red eye" when injected with degradation products. Chemical characterization indicated the toxic agent generated from degraded CA is water soluble, acidic and less than 20000 mw. The blood chemistry and eye evaluation of the rabbits strongly indicated that oxidative stress of CA at some point created degradation products that can reproduce some of the symptoms identified at Hospital A.