Study of drug-protein binding by affinity chromatography: interaction of bovine serum albumin and salicylic acid.

The affinity chromatographic technique was used to study the interaction of bovine serum albumin and salicylic acid at 3.3 +/- 1.1 degrees. Beaded agarose gel, on which the albumin was immobilized by covalent linkage, was packed in a column as an affinity adsorbent. Frontal analysis was performed on this column to evaluate the binding parameters for the interaction. The effect of albumin immobilization on drug binding was investigated by comparing the binding parameters of two affinity adsorbents, directly coupled albumin and albumin coupled through a spacer arm. The latter mode of attachment gave binding characteristics comparable to those of the soluble albumin. The method is simple and precise. The affinity adsorbent can be used repeatedly for many months for various drugs, including those that do not diffuse through dialysis membranes.

Dissolution of bupivacaine 3-hydroxy-2-naphthoate into phosphate buffers.

Dissolution behaviour of bupivacaine 3-hydroxy-2-naphthoate (BUPNH) into phosphate buffers, pH 7.4 was investigated at 25 degrees and 37 degrees C. Although the dissolution pattern of the salt at 25 degrees C was normal, i.e., the concentrations of the acid and base component agreed, during the entire dissolution period, that at 37 degrees C was anomalous. The dissolution consisted of two phases, i.e. an initial normal phase was followed by a second slower phase in which the concentration of the acid became, at equilibrium, markedly higher than that of the base. This unusual dissolution behaviour at 37 degrees C was shown to be due to the precipitation of the base, which, in turn, is attributed to the unusual temperature dependency of the solubility of the base in phosphate buffers, i.e. decrease in solubility with increasing temperature.

Activated carbon beads for the removal of highly albumin-bound species.

Activated carbon beads in which 5% activated carbon powder was embedded in 4% agarose were prepared by the emulsion technique. The column of the beads was demonstrated to effectively remove salicylic acid, warfarin, and long-chain fatty acids from solutions containing albumins by either zonal or frontal analysis under the condition of 0.1 M NaCl, pH 3.0 (HCl). The beads were also demonstrated to purify a commercial human serum albumin preparation from residual fatty acids. The beads would be of value in many biochemical purification processes in which activated carbon is employed.

Multienzyme control serum (Seraclear-HE) containing human enzymes from established cell lines and other sources. 3: Evaluation as candidate working enzyme reference material for gamma-glutamyltransferase.

Seraclear-HE, containing gamma-glutamyltransferase (GGT, EC 2.3.2.2) derived from the cell culture of a human macrophage cell line, was evaluated as a candidate enzyme reference material (ERM) to calibrate routine methods in terms of a Reference Method for GGT. We have compared this preparation with commercially available materials, including Certified Reference Material 319, at 30 degrees C and 37 degrees C with respect to kinetic properties and with respect to commutability between the Reference Method and each of 15 analytical procedures involving five structurally different donor substrates. GGTs of human origin are far more commutable with reagents of varied types than are GGTs derived from animals. Calibration of 44 patients' sera with Seraclear-HE decreased average intermethod variation from 20% to approximately 4%, whereas GGTs of animal origin showed intermethod variations of approximately 30% with no benefit from calibration. Seraclear-HE is promising as a secondary or working ERM to be used as an intermethod calibrator.

Prevention of gastrointestinal absorption of phenobarbital by activated carbon beads as an oral adsorbent.

The in vitro adsorption characteristics of activated carbon beads suitable for oral administration and the original fine powder were examined, using phenobarbital as the test drug. The extent and rate of drug adsorption on carbon in the beads were almost equal to those on the powder. In three healthy volunteers, 10 g of activated carbon beads administered orally 20 min after 120 mg of phenobarbital, reduced the total bioavailability by 57% (p less than 0.005), based on the salivary AUC-value during 96 h and the achieved peak concentration of the drug in salvia by 51%. These results demonstrated the potency of activated carbon beads as a gastrointestinal adsorbent in acute intoxications from phenobarbital.

Multienzyme control serum (Seraclear-HE) containing human enzymes from established cell lines and other sources. 2: Evaluation as candidate working enzyme Reference Material for alanine and aspartate aminotransferases.

Seraclear-HE, containing seven enzyme analytes from human sources, was evaluated as an intermethod calibrator for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) to transfer Reference Method values to seven routine methods, including one based on hydrogen peroxide detection for possible unification of values (interlaboratory comparability of data). The commutabilities of AST from erythrocytes and ALT from a hepatoma cell line were studied between the consensus methods of Japan Society of Clinical Chemistry (chosen as the Reference Methods) and each of the automated routine methods at reaction temperatures of 30 degrees C and 37 degrees C. For AST, calibration of patients' sera with Seraclear-HE decreased average intermethod variation (CV) from 12% to 2%; for ALT, the decrease was from 20% to 3%. For both enzymes, Seraclear-HE was judged to be commutable between the Reference Methods and each of the methods investigated. The limitations for such use are discussed.

Binding capacities of human serum albumin monomer and dimer by continuous frontal affinity chromatography.

Human serum albumin monomer and dimer obtained by fractionation of a commercial preparation were immobilized on CH-Sepharose 4B by covalent coupling. For salicylic acid, warfarin, phenylbutazone, mefenamic acid, sulphamethizole and sulphonylureas, the binding capacities of the monomer and dimer were compared by continuous frontal affinity chromatography. The salicylate-binding capacities of both monomer and dimer were essentially retained upon immobilization. For these drugs, the dimer showed only about 10-30% less capacity per monomeric unit than that of the monomer, the reduction being associated for most drugs with the intrinsic binding constant rather than with the number of binding sites.

Mutual displacement interactions in the binding of two drugs to human serum albumin by frontal affinity chromatography.

A continuous frontal analysis chromatographic method was developed for studying the simultaneous binding of two drugs or ligands with an immobilized macromolecule. The usefulness of this method was demonstrated in the interactions of sulphamethizole and salicylic acid with human serum albumin (HSA). The mutual inhibitory effect on the binding of one drug of the presence of the other was directly shown to be due to displacement of the bound drug from HSA by the other. On the basis of a double-reciprocal plot analysis, these two drugs are interpreted as competing for the same primary binding sites.

Effect of activated carbon beads on serum lipid levels and fecal bile acid excretion in rats.

The effects of oral activated carbon beads on the total serum cholesterol and triglyceride levels and on the fecal bile acid excretion in rats fed a basal or high cholesterol diet containing 5% activated carbon beads for 6 weeks were investigated. The beads appeared to exert little effect on the growth rate of rats and no tendency towards constipation was also observed. Although treatment with activated carbon beads gave little influence on the total serum cholesterol and serum triglyceride levels in rats fed either a basal or high cholesterol diet, the beads did produce a significant rise in the total fecal bile acid excretion. The extra fecal bile acids resulted chiefly from an increase in lithocholic acid. Furthermore, the beads showed a tendency to inhibit absorption of dietary cholesterol from the gastrointestinal tract in rats fed a high cholesterol diet. These results suggested the possibility of activated carbon beads as a hypocholesterolemic agent through binding with bile acids in the intestine.

Multienzyme control serum (Seraclear-HE) containing human enzymes from established cell lines and other sources. 1: Preparation and properties.

We have developed a new multienzyme control serum, Seraclear-HE, which was designed to function not only as an accuracy and precision control serum but also as an intermethod calibrator for unifying interlaboratory clinical enzyme data in terms of reference method values. Seraclear-HE contains as analytes the following enzymes of human origin only: aspartate aminotransferase (AST, EC 2.6.1.1) and lactate dehydrogenase (LD, EC 1.1.1.27) from erythrocytes; alanine aminotransferase (ALT, EC 2.6.1.2) from a hepatoma cell line; alkaline phosphatase (ALP, EC 3.1.3.1) from an amnion cell line; creatine kinase (CK, EC 2.7.3.2) from an embryo kidney cell line; gamma-glutamyltransferase (GGT, EC 2.3.2.2) from a macrophage cell line; and amylase (AMY, EC 3.2.1.1) from urine and saliva. The seven partly purified enzymes were lyophilized in partially delipidated human serum containing sucrose (50 g/L), pyridoxal 5'-phosphate (30 mmol/L), and other stabilizers. The material is stable for at least 2 years at temperatures < or = 10 degrees C. For two concentrations of this preparation, reference method values (mainly International Federation of Clinical Chemistry and Japan Society of Clinical Chemistry) obtained at both 30 degrees C and 37 degrees C are assigned.