We had reported microencapsulation of activated charcoal (AC) and coating of spherical AC with gelatin for direct hemoperfusion (DHP). Then poly-HEMA was chosen for the coating of pitch bead AC (BAC-MULL). The double coated AC with poly-HEMA is used in clinics. Recently non-coated AC (TN006) was evaluated for DHP and it was found that TN is a suitable adsorbent to remove toxins in blood directly by us. On the other hand uncoated BAC biocompatibly modified with heparin was proposed for DHP by Katakura et al. Uncoated AC, which has been washed carefully, rubbs each other during the packaging in column and particles might be formed by the rubbing when the AC is not hard and strong enough. Fortunately poly-HEMA membrane on the AC is very thin and the permeable resistance could be minimized.
Four AC studied are three commercially available AC, BAC-MULL, MUAZ and MULE, and TN006 which is made of a polystyrene derivative. Compressive strengths were 4.0Kg (TN), 0.9 (LL), 0.8 (AZ) and 0.6 (LE). Numbers of released particle during agitation of three BAC coated twice with poly-HEMA and TN were counted. Order of particles released were the same of compressive values. Coating of BAC is strongly required to protect particle fragmentation. Creatinin clearances are not so different as shown in Fig. 1 and 3 when flow rate is slower than 200ml/min. MUAZ and MULE show better clearance than MULL and TN006 in adsorption of middle molecular solute. Marked difference was not observed in in vivo studies using three coated BAC and non-coated TN.
