Immobilized drugs and enzymes in biochemical pharmacology. Perspectives and critique

Bioactive Polymers XXXVI. Controlled Release of Cephalosporine C from Cellulosic Derivatives

Cephalosporine C was coupled onto cellulosic derivatives of N-(4-carboxy phenyl)carbamoylmethyl cellulose and crosslinked carboxymethyl cellulose to achieve controlled drug release. Starting from a mathematical model, the in fluence of certain parameters of the reaction (drug/support, activator/support molecular ratios, and reaction times) on the amount of Cephalosporine C chem ically bound to the cellulose products was determined. Evaluation of the cou pled products show extended activity by the release of Cephalosporine C by hydrolysis.

Preparation and characterization of chitosan-entrapped microsomal UDP-glucuronyl transferase

The hepatic microsomal UDP-Glucuronyl transferase which catalyze the glucuronidation of drugs, pesticides, carcinogens and other xenobiotics, was immobilized by entrappment in chitosan. Chemical and physical characterization were made by using 1-naphthol as substrate. Thermal, storage and operational stabilities of the immobilized enzyme was also searched and found to be better in comparison with the free enzyme. In conclusion, chitosan gel beads appear to have good characteristics for use as UDPGT immobilization support suitable for large scale use and offer the prospect that immobilized UDPGT may become an important form of catalyst in medicine.

Bioactive polymers 55. Synthesis and characterization of a macromolecular drug based on 5-acetylamino-2-sulfamoyl-1,3,4-thiodiazole

The paper studies the coupling reaction by covalent bonding of acetylamino-2-sulfamoyl-1,3,4-thiodiazole (AcAA) on the poly(acrylic acid-costyrene) copolymer (PAcA-S) in homogeneous system, in the presence of dicyclohexylcarbodiimide (DCC) as activator. The influence of some factors on coupling efficiency (the drug/support ratio, time, volume of solvent), as well as the mathematical model correlating the amount of coupled drug with these parameters is established. Maximum amounts of drug (28%) are chemically bound when employing maximum values of the parameters mentioned (i.e., AcAA/PAcA-S ratio = 2 mole/mole; time = 50 h; THF volume = 60 ml). Physicochemical and spectral analyses evidence the existence of some chemical bonds of the -CO-NH-SO2-type between the macromolecular support and the drug. In vivo tests have demonstrated the gradual hydrolysis of the chemical bonds as well as the release of the drug, due to the diuretic effect produced.

Cell surface actions of adriamycin

Adriamycin has a vast range of reported actions on the structural and functional properties of cells. This review summarizes the literature on the ability of the drug to modulate the cell surface membrane and attempts to address the question of how such actions could be linked to cytotoxicity. In addition, we consider the use of polymer immobilization of adriamycin to separate intracellular from plasma membrane effects of the drug, and show how this approach has been helpful in interpreting the pharmacology of adriamycin. Finally, a range of biophysical and spectroscopic approaches to defining the molecular details of adriamycin-bilayer interactions is surveyed, and the results used to discuss a model for how this antineoplastic agent binds to membranes.

Immobilization of a primary amine-containing drug, adriamycin. Coupling to crosslinked polyvinyl alcohol and mechanistic comparison of hydrolytic stability

Literature reports have described the covalent coupling of the primary amine-containing anticancer drug, adriamycin, to polymeric supports through the amine group on the drug. These reports also have described drug mechanism studies with the immobilized adriamycin, where the release of the drug would undermine the validity of the conclusions. In the present paper, detailed experimental conditions are given for preparation of nonwater-soluble particles of polyvinyl alcohol by crosslinking water-soluble polyvinyl alcohol with 1,4-benzenedicarboxaldehyde, and for activation with cyanuric chloride and covalent attachment of adriamycin. The expected stability of this drug-support linkage against hydrolytic cleavage is compared mechanistically to that expected for less stable coupling through a carbamate linkage or for less stable coupling via an azomethine link.