SYNTHETIC MODIFICATION OF PAN MEMBRANE - BIOCOMPATIBILITY AND FUNCTIONAL-CHARACTERIZATION

A disturbing interaction of PAN membranes and the bradykinin generatio n system particularly in the presence of angiotensin converting enzyme inhibitors has been described. A modified new membrane, SPAN (special PAN), was produced by varying the polymer components in type and comp osition, in particular by a reduction in Na-Methallylsulfonate. Althou gh the SPAN membrane successfully averted the bradykinin generating ab ility of PAN, it was important to determine whether such a modificatio n did not lead to a loss of the satisfactory biocompatibility profile characteristic of the parent membrane. For this purpose, we conducted the present clinical study in nine patients comparing 3 membranes; (i) a polysulphone membrane (F60S); (ii) PAN; and (iii) SPAN, to examine the clinical biocompatibility profile and performance of the new membr ane. A small increase in C5a with F60S and SPAN was found which is in the range expected for highly biocompatible synthetic membranes. The t hree dialysers had a similar inert profile for terminal complement com plex arterial values, and had similar venous values. A minimal nonsign ificant decline in white cell count was observed at 15 min for all dia lysers, but otherwise WBC counts were unchanged. Platelet counts were unchanged throughout treatment for the three dialysers. Arterial and v enous thrombin-anti-thrombin complex values were similar for all three dialysers. F60S and SPAN dialysers had similar urea clearances. PAN u rea clearance was slightly lower than the other two dialysers. The res ults with creatinine clearances were similar to those of urea. beta(2) , Microglobulin clearance was substantial for F60S dialysers. SPAN dia lysers had a significant beta(2) microglobulin clearance that was slig htly less than F60S. PAN dialysers had minimal clearance for this mole cule at the time points studied. In summary, the results of the presen t study indicate that the synthetic modification of PAN to abrogate it s bradykinin generating effect did not adversely affect its biocompati bility profile and that the new membrane behaves in the range typical of its synthetic congeners.