EFFECTS OF COLLOIDAL-CHEMICAL PROPERTIES OF ACTIVATED CHARCOALS ON THEIR THERAPEUTIC EFFICACY T. N. Nevar, 1 T. A. Savitskaya, 2 A. V. Osipova, 3 S. E. Makarevich, 1 N. G. Tsigankova, 1 and D. D. Grinshpan 1 Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 6, pp. 44 – 48, June, 2007. Original article submitted November 24, 2005. We report studies addressing the colloidal-chemical properties (stability, rheology, adsorption of model sub- stances) of suspensions of fibrous activated charcoal tablets in which polymer binders were starch and a new water-soluble cellulose derivative. Medical use of charcoal tablets based on the new binder was shown to be effective. The most widely used enterosorbents are agents based on activated charcoals (AC), which are used as powders, gran- ules, and tablets [1]. Use of the first two of these therapeutic forms is limited because of the inconvenience involved in taking them, while the tablet form of AC has low efficacy be- cause of the high content of polymer supporting substances adsorbed onto the surface of the charcoal particles to “glue” them together. For this reasons, most charcoal tablets pro- duced by the pharmaceutical industry are unable to disperse in the liquid phase and, consequently, have low adsorptive capacity in relation to toxins [2]. The aims of the present work were to undertake a com- parative study of the effects of polymer binders of different chemical types on the adsorptive-structural characteristics of AC and on the sedimentary and rheological properties of their aqueous suspensions, and to establish the relationship between the colloidal-chemical properties of suspensions of tablet forms of AC and their therapeutic efficacies. METHODS Studies were performed using fibrous activated charcoal (FAC) grade AUT-MI from Svetlogor PO “Khimvolokno” for medical use as “Belosorb-P” powder and experimental tablets based on this FAC and containing starch or a new wa- ter-soluble cellulose derivative (WSCD) as the binder. Tab- lets containing the WSCD are known as Uglesorb (VFS RB 0491 – 2000) and have been approved by the Ministry of Health of the Republic of Belarus for medical use. The adsorption-structural characteristics of the initial FAC and ground tablets were assessed in terms of the low-temperature adsorption of nitrogen, measured using a Nova 1200e (Quantochrome, USA) instrument 4 . Specific surfaces (S N2 ) of sorbents were assessed using the BET equa- tion, total pore volume (V S ) and micropore volume (V MI ) and mesopore volume (V ME ) were assessed using the program- ming provided with the instrument. The measurement error was 2 – 5%. The adsorbing activity of samples in relation to tracer substances was characterized by adsorption G , which was the quantity of substance adsorbed from aqueous solutions per unit weight of adsorbent in static conditions. Markers were iodine, methylene blue (MB), and antipyrine, which simulate low molecular-weight toxins, as well as Congo red (CR) and cyanocobalamin (vitamin B 12 ), representing molecules of in- termediate molecular weight. Solution concentrations and durations of contact with adsorbent were selected in accord with recommendations of current pharmacopeia articles on AUT-MI [3]. Adsorption of model substances was calculated from the decrease in the concentration of the adsorbed sub- stance in a specified volume of solution after reaching ad- sorption equilibrium [4]. Iodine concentrations in solutions were determined by titration with 0.1 N sodium thiosulfate (Na 2 S 2 O 3 ) solution; concentrations of stains and vitamin B 12 were estimated spectrophotometrically using a KFK-2 Pharmaceutical Chemistry Journal Vol. 41, No. 6, 2007 332 0091-150X/07/4106-0332 © 2007 Springer Science+Business Media, Inc. 1 Belarus State University Science Research Institute of Physicochemical Problems, Minsk. 2 Belarus State University, Minsk. 3 RDUP MTZMedservis, Minsk. 4 Studies were performed under the direction of Candidate of Technical Sci- ences A. G. Kulakov in the ITMO Laboratory, National Academy of Sci- ences of the Republic of Belarus (Director: Professor L. L. Vasil’ev).