Activated carbons as medical adsorbents

Activated carbon is an adsorbent as described in Chapter 3, Footnote 93, and in Appendix A2. One of the first large-scale uses of activated carbon as an adsorbent was in military gas masks where complete removal of contaminants was essential. Another essential application is removal of mercury contained in emissions from coal-fired power stations, medical incinerators, and in produced natural gas at wellheads. A value provided in cleaning operations by activated carbon adsorbent is that multiple solvent components can be captured within the same apparatus... 

Activated carbons are widely used for treatment of acute and chronic poisoning as oral adsorbents and for blood purification. However, medical carbons currently available are predominantly microporous and their use is therefore limited to... 

The activated carbons obtained have a potential for medical applications in treatment of chemical and biological poisoning as oral adsorbents and in extracorporeal blood detoxication. 

The most pharmaceutical value of adsorption is that of unwanted active materials in solution onto solids such as activated carbon, kaolin, and tannic acid. In addition, adsorption may cause formulation problems when active drugs or inert excipients (i.e., preservatives) adsorb onto containers or medical devices. 

Adsorbents are used in medicine mainly for the treatment of acute poisoning, whereas other extracorporeal techniques based on physico-chemical principles, such as dialysis and ultrafiltration, currently have much wider clinical applications [1]. Nevertheless, there are medical conditions, such as acute inflammation, hepatic and multi-organ failure and sepsis, for which mortality rates have not improved in the last forty years. These conditions are usually associated with the presence of endotoxin - lipopolysaccharide (LPS) or inflammatory cytokines - molecules of peptide/protein nature [2]. Advantages of adsorption over other extracorporeal techniques include ability to adsorb high molecular mass (HMM) metabolites and toxins. Conventional adsorbents, however, have poor biocompatibility. They are used coated with a semipermeable membrane of a more biocompatible material to allow for a direct contact with blood. Respectively, ability of coated adsorbents to remove HMM solutes is dramatically reduced. In this paper, preliminary results on adsorption of LPS and one of the most common inflammatory cytokines, TNF-a, on uncoated porous polymers and activated carbons, are presented. The aim of this work is to estimate the potential of extracorporeal adsorption technique to remove these substances and to relate it to the porous structure of adsorbents. 

Carbon in its various forms such as pyrolytic carbon, glassy carbon, carbon fiber, carbon fiber reinforced composites, and activated carbon has been a potential and important material in medical science and in medicinal applications. This is due to its properties such as good biocompatibiUty, nontoxicity, no immune reaction with the body, low density, chemical inertness, low coefficient of friction, elastic modulus similar to that of bone, and high adsorption capacity. Some of these applications of carbon materials have been discussed elsewhere" and are beyond the scope of this book. In this section we shall look into some of the medicinal applications based on adsorption by active carbons. Adsorbent carbons in the form of charcoal and activated carbons have been in use for medicinal and health applications for centuries and have been listed in the pharmacopoeia as antidotes and intestinal adsorbents. 

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