Membrane-Immobilized Liver Microsome Drug Detoxifier
The common occurrence of poisoning due to drug overdose has led to an increasing need for a safe, simple, effective, and inexpensive means of removing such drugs from the blood in the emergency treatment of drug-overdose victims. Various devices and techniques based on extracorporeal blood processing have been investigated. Physical techniques include hemodialysis (Kennedy et al., 1969), charcoal adsorption (Widdop et al.,1975; Chang et al., 1973), and ion-exchange adsorption (Rosenbaum et al., 1971; Medd et al., 1974). Biological techniques include liver perfusion (McDermott and Norman, 1971), liver slice perfusion (Koshino et al., 1975), perfusion over hepatic cell suspensions in direct contact with the blood (Eisman and Soyer, 1971; Soyer et al., 1973), and perfusion through hollow fibers containing cultured hepatic cells on the outer surface of the fibers (Wolf and Munkelt, 1975). It is well accepted that the biological system responsible for detoxification of a variety of drugs is located in the smooth endoplasmic reticulum of hepatic cells which can be isolated as microsomes by cell fractionation. The microsomes contain a complex mixture of enzymes, including cytochrome P-450, which requires the coenzyme NADPH and molecular oxygen for drug detoxification. In general these detoxification enzymes modify toxins by increasing their polarity and consequently their aqueous solubility, thus decreasing their permeation into tissues (Mandel, 1971) and promoting excretion. The chemical modifications catalyzed by the microsomal drug detoxification enzymes include, among others, hydroxylation, demethylation, and conjugation reactions. Several of the microsomal detoxification enzymes have been purified (Lu and Levin, 1974; Brunner, 1975; Ziegler and Mitchell, 1972) and at least two have been immobilized by covalent bonding to insoluble particles (Brunner, 1975; Parikh et al., 1976; Sofer et al.,1975). One approach for utilization of these enzymes in an extracorporeal drug detoxification system is to purify the individual enzymes and then reconstitute the multienzyme complex by binding to insoluble particles. An alternative approach, the one we have chosen, is to utilize the isolated microsomes themselves. This method has the advantage of simplicity and lower cost. More importantly, in contrast to the former approach, it assures that all the microsomal enzymes are present in proportions and molecular arrangement closely resembling the in vivo state. We have used an extracorporeal hollow fiber-based enzyme reactor in an attempt to develop a therapeutic technique suitable for treatment of drug and poison detoxification. Since all the protein components of the system are impermeable to the hollow fiber membranes, adverse immunological reactions will be avoided. In addition, the safety of blood processing using hollow fiber devices has been well established in recent years by extensive use in hemodialysis.
KeywordsHollow Fiber Microsomal Enzyme Hollow Fiber Membrane Glucose Dehydrogenase Detoxification System
Unable to display preview. Download preview PDF.
- Brunner, G., 1977, Refixation of solubilized and purified microsomal enzymes: a new approach towards an extracorporeal detoxification in man, in: Third Int. Conf. Enzyme Eng. (Reed College, Portland, Oregon, Aug. 3–8, 1975) (E. K. Pye and L. B. Wingard, eds.), Plenum Press, New York. (in press).Google Scholar
- Eisman, B., and Soyer, T., 1971, Prosthetics in hepatic assistance, Transplant Proc. 3: 1519.Google Scholar
- Gillette, J. R., 1963, Metabolism of drugs and other foreign compounds by enzymatic mechanisms, Progr. Drug Res. 6: 13.Google Scholar
- Gillette, J. R., Grieb, W., and Seasame, H., 1963, Mechanisms of apparent inhibition of microsomal drug enzymes, Federation Proc. 22: 366.Google Scholar
- Koshino, I., Castino, F., Yoshida, K., Carse, C., Kambic, H., Scheucher, K., Kretz, A. P., Malchesky, P. S., and Nose, Y., 1975, A biological extracorporeal metabolic device for hepatic support, Trans. Amer. Soc. Artificial Internal Organs 21: 492.Google Scholar
- Kupfer, D., and Rosenfeld, J., 1973, A sensitive radioactive assay for hexobarbitual hydroxylase in hepatic microsomes, Drug Metabolism and Disposition 1: 760.Google Scholar
- Lu, A. Y. H., and Levin, W., 1974, The resolution and reconstitution of the liver microsomal hydroxylation system, Biochim. Biophys. Acta 344: 205.Google Scholar
- Mandel, H. G., 1971, Pathways of drug transformation: biochemical conjugations, in: Fundamentals of Drug Metabolism and Drug Disposition (B. N. La Du, H. G. Mandel, and E. L. Way, eds.), pp. 149–205, The Williams & Wilkins Company, Baltimore.Google Scholar
- McDermott, W. V., and Norman, J. C., 1971, Metabolic considerations in treatment of liver failure with particular reference to use of ex vivo perfused pig liver, Transplant Proc. 3: 1509.Google Scholar
- Soyer, T., Lempinen, M., and Eiseman, B., 1973, In vitro extracorporeal liver slices and cell suspensions for temporary hepatic support, Ann. Surg. 177: 393.Google Scholar
- Wolf, C. F. W., and Munkelt, B. E., 1975, Bilirubin conjugation by an artificial liver composed of cultured cells and synthetic capillaries, Trans. Amer. Soc. Artificial Internal Organs 21: 16.Google Scholar