Medical Carbons - Need for Mesopores

Introduction At present medical activated carbons (AC) are used as oral adsorbents and for haemoperfusion mostly in acute poisoning with small molecular weight toxins. Respectively, the efforts to make an efficient medical activated carbon are aimed at developing its microporous structure. Potential for therapeutic use of activated carbon with larger pores – mesopores is almost completely overlooked and ignored. The main reasons for this are two-fold. It is a common perception that oral administration of activated carbon is efficient only within first 1-2 hours after acute poisoning, and acute poisoning is usually caused by small molecules of drugs, pesticides and other chemicals. In haemoperfusion mostly coated activated carbons are used. The coating is usually made of a more biocompatible cellulose membrane. Although AC coating resolved the problem of its poor biocompatibility, it created another one, which restricted use of adsorption therapy in comparison with alternative blood purification techniques such as dialysis or filtration. A 0.5-5 μm thick semi-permeable coating (i) slows down the external diffusion to the adsorbent surface and (ii) prevents larger molecules from contact with the adsorbent completely. The coating significantly reduces efficiency of adsorption of molecules with molecular mass 1,000-20,000 (so-called ‘middle molecules’) and completely prevents adsorption of large molecules such as proteins, glycoproteins, lipopolysaccharide and circulating immune complexes which are responsible for a great number of pathological conditions and acute and chronic poisonings. These include poisoning with microbial toxins, autoimmune diseases, septic and toxic shock. Examples of such pathogenic substances are given in Table 1.