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Biomedical subjects

G S Banker

Publications and source records attributed to G S Banker.

At least 19 recordsLinked to original sources
PubMed2001

Examination of oxidized cellulose as a macromolecular prodrug carrier: preparation and characterization of an oxidized cellulose-phenylpropanolamine conjugate.

The purpose of this study was to investigate the use of 6-carboxycellulose (OC), a biocompatible and bioresorbable polymer, as a prodrug carrier for amine drugs. Phenylpropanolamine hydrochloride (PPA.HCl) was used as a model drug. OC and PPA were reacted in dimethylformamide (DMF) in the presence of 1,3-dicyclohexylcarbodiimide (DCC) for 2.5 days at room temperature. Filtration, followed by washing with methanol, and subsequent drying under vacuum, produced the conjugate in 65-78% yield. The amount of PPA in the product, determined from the difference in the carboxylic content before and after the reaction, was 24.2% (w/w), corresponding to a degree of substitution (DS) value of 0.7. The Fourier transform-infra red (FT-IR) spectrum of the conjugate, compared with that of OC and PPA.HCl, showed a new band at about 1533 cm(-1) attributable to a C = O (amide II) stretching and N single bond H (amide I and amide II) bending vibrations, a decrease in intensity of the characteristic free carboxylic acid carbonyl stretching band at about 1748 cm(-1), and a strong band at 1663 cm(-1) due to C = O (amide I) stretching vibration, suggesting that the OC is linked to PPA via an amide bond. The solid-state carbon-13 cross polarization/magic angle spinning nuclear magnetic resonance ((13)CCP/MAS NMR) spectrum of the conjugate was also consistent with this structure. The release studies performed in pH 4.5, 5.5, and 7.4 buffer solutions and in rat liver homogenate (pH 7.4), showed the conjugate to be more susceptible to hydrolysis at a lower pH and in the presence of rat liver homogenate. In conclusion, the results presented show that OC can be covalently linked to amine drugs via an amide bond in DMF using DCC as a coupling agent, and provide a macromolecular prodrug delivery system.

Cellulose↗
PubMed2001

Compression, compaction, and disintegration properties of low crystallinity celluloses produced using different agitation rates during their regeneration from phosphoric acid solutions.

The tabletting characteristics of low crystallinity celluloses (LCPC)-LCPC-700, LCPC-2000, and LCPC-4000-prepared using agitation rates of 700, 2000, and 4000 rpm, respectively, during their regeneration from phosphoric acid, were evaluated and compared with those of Avicel PH-102 and Avicel PH-302. The mean deformation pressure values calculated from the linear region of the Athy-Heckel curves indicated LCPC-4000 to be the most ductile material. The area under the Athy-Heckel curve for LCPC-4000 was 330 MPa, whereas LCPC-700 and LCPC-2000 showed a corresponding value similar to that of Avicel PH-102 and Avicel PH-302 (192-232 MPa). The tensile strength of LCPC and Avicel compacts increased linearly with increasing applied pressures. A comparison of the area under the tensile strength-compression pressure curves indicated that LCPC-4000 formed the strongest tablets. The strengths of LCPC-700 and LCPC-2000 compacts, in contrast, were slightly lower than that of Avicel PH-302 and Avicel PH-102, respectively. The compacts of both LCPC-4000 and Avicel PH-102 were intact in water for 6 hours, whereas LCPC-2000 and Avicel PH-302 compacts disintegrated in 4 minutes and 2 minutes, respectively. In conclusion, LCPC-4000 was the most ductile material and exhibited the highest compression and compaction characteristics. The corresponding properties of LCPC-700 and LCPC-2000, in contrast, were comparable to that of Avicel PH-102 or Avicel PH-302.

Cellulose↗
PubMed1995

Isolation and characterization of two major degradation products of dyclonine hydrochloride.

Dyclonine hydrochloride, a local anesthetic, is known to degrade in aqueous media. In this paper, the isolation and characterization of two major degradation products, formed by heating of an aqueous solution of dyclonine hydrochloride for 2 weeks at 50 degrees C, are presented. The proton and carbon-13 nuclear magnetic resonance, infrared, and mass spectral data reported conclusively show the two products to be 1-(4-butoxyphenyl)-2-propen-1-one and 1-(4-butoxyphenyl)-3-hydroxy-1-propanone. The proton and carbon-13 nuclear magnetic resonance spectral data of the free dyclonine base are also included.

Anesthetics, Local↗
PubMed1982

Quantitative evaluation of pharmaceutical effervescent systems I: Design of testing apparatus.

Two new devices were developed to monitor the reactivity of pharmaceutical effervescent systems. The first method monitored carbon dioxide pressure generation during the effervescent reaction in a plastic pressure vessel fitted with a pressure gauge. The second method monitored weight loss, attributed to carbon dioxide loss to the atmosphere, by means of a double cantilever beam and an electromagnetic proximity transducer. In the pressure device, the quantification of an effervescent reaction was accomplished by measuring the dissolution time of the effervescent system and the pressure generated. Quantification of an effervescent reaction using the beam device utilized the total carbon dioxide weight loss, the rate of weight loss, and the effervescent reaction lag time.

Bicarbonates↗
PubMed1982

Quantitative evaluation of pharmaceutical effervescent systems II: Stability monitoring by reactivity and porosity measurements.

The stability of selected effervescent tablet systems was monitored by means of mercury intrusion porosimetry and by a cantilever beam/proximity transducer balance. The porosity measurements proved to be useful in elucidating tablet pore structure changes over time. The measured parameter, percent pores greater than the experimental range, was a useful measure of porosity for statistical evaluations. The study showed that compression pressure and manufacturing conditions are not significant factors in the stability of an effervescent tablet system when nonhygroscopic materials are used.

Bicarbonates↗
PubMed1982

Paired-ion high-performance liquid chromatographic assay for sulfinpyrazone in plasma.

A specific and sensitive liquid chromatographic method is reported for the assay of sulfinpyrazone in plasma utilizing ion pairing between the tetrabutylammonium cation and the sulfinpyrazone anion. The method is rapid in that conventional extraction procedures are avoided in favor of using disposable cartridges packed with an octade-cylsilane bonded phase as a means of separating the drug from plasma. The samples were chromatographed on a C18 reversed-phase column using a mobile phase consisting of 0.005 M tetrabutylammonium phosphate in methanol-water (56:44). The coefficient of variation obtained was 4.5% and the response was linear over a range of 0.2-80 micrograms/ml.

Chromatography, High Pressure Liquid↗
PubMed1980

Cost evaluation of alternative pharmaceutical tableting processes by simulation.

A simulation model and a subsequent computer program were developed as experimentation methods for evaluating tableting processes with respect to cost. These methods also allow estimation of the various times involved in a tableting operation (e.g., the processing time). The model was programmed in FORTRAN using the GASP IV simulation language. After verification of the program, experiments were run that involved comparing different levels of specific input variables to determine which variable had an effect on the cost-time relationships of a particular processing method. Among the possible input variables chosen for evaluation were the drying method, the type of tableting machine, the batch size, the labor rate, and the operation of the equipment in the process. An analysis of variance was made, and three separate regression equations were developed that described the relationship between the input variables and the dependent variables of processing cost and time. Graphs were developed from the regression equations by manipulating them through series of different independent variables. These graphs then were used in determining minimum costs and times, breakeven points, and rates of change, as well as in simple evaluation of processes through graphic representation. By using the simulation program to run experiments and then by analyzing them, results can be obtained to help in making intelligent decisions about the cost-time relationships of a particular tableting procedure before it is implemented.

Chemistry, Pharmaceutical↗
PubMed1977

Determination of porosity and pore-size distribution of aspirin tablets relevant to drug stability.

Total porosity and pore-size distribution of aspirin tablets prepared from aspirin, starch USP, and precipitated colloidal silicon dioxide were determined using mercury porosimetry. The model represented a hydrolyzable drug substance in combination with simple excipients. The role of starch and silicon dioxide on the microstructure of the tablets was investigated, as was the chemical stability of various systems. In general, the porosity of tablets containing a constant quantity of starch increased linearly with silicon dioxide concentration. Examination of the pore-size distribution, however, revealed that a low concentrations silicon dioxide functioned primarily to reduce the size and volume of coarse pores representing the spaces between the agglomerates of starch and aspirin particles. This effect was optimum at 3%. A further increase in silicon dioxide concentration produced tablets with relatively larger pore sizes. Studies of changes in the porosity characteristics of tablets as influenced by water vapor over time showed distinct differences in this complex parameter. A unique trend in the change of the pore-size distribution was noted with tablets containing 3% silicon dioxide. These observations are discussed relative to the stability of aspirin tablets in which this concentration of silicon dioxide produced a maximum stabilizing effect.

Aspirin↗
PubMed1977

Bactericidal properties of quaternary ammonium compounds in dispersed systems.

Alkyltrimethylammonium bromides of selected chain length were synthesized and characterized with respect to their bactericidal properties. A partitioning method was developed, and the aqueous phases of the partitioned systems were evaluated for their antibacterial activity against Staphylococcus aureus. The relationships between the quaternary ammonium compound chain length and the aliphatic alcohol chain length were determined. The effect of selected hydrocarbons on the bactericidal effectiveness of the systems was studied. Cream systems corresponding to the partitioned systems were prepared and evaluated against S. aureus. The relationship between the aqueous phase concentration of the bactericidal agent was studied, and a correlation was shown between the bactericidal activity of the partitioned systems and cream systems.

Anti-Infective Agents, Local↗
PubMed1977

Recording pH method of characterizing composition and monitoring dissolution profile of an anhydride-acid copolymer and its salt derivatives.

A sensitive potentiometric monitoring method was developed that permits the continuous measurement of the disolution profiles of methyl vinyl ether-maleic anhydride-acid copolymers and salt derivatives. Three distinct rate periods were observed in the dissolution rate of the anhydride copolymer, expressed as percent anhydride dissolved, was independent of sample weight over the weight range studied. The acid form of the copolymer showed only one dissolution rate period, with dissolution being very rapid. The rapid initial pH decrease observed during the first stage of dissolution for a series of anhydride-acid copolymer powder samples correlated closely with the anhydride-acid ratio, permitting chemical characterization of the copolymer functionality simultaneously with the analysis of dissolution profiles. Similarly, the extent of copolymer alkaline salt conversion was inversely proportional to the initial maximum pH increase observed during the first stage of dissolution of these salts. Mechanisms of dissolution of copolymer powder materials are discussed and compared to the dissolution of compressed disks and films reported previously.

Hydrogen-Ion Concentration↗
PubMed1976

Attainment of highly uniform solid drug dispersions employing molecular scale drug entrapment in polymeric latices.

The uniformity of distribution attainable for an amine drug in solid dispersions prepared using a molecular scale entrapment procedure was investigated. Excellent reproducibility of drug content throughout the entire entrapment product was demonstrated in both flocculated (high drug levels) and deflocculated (low drug levels) systems. Drug content and content uniformity were found to be predictable for deflocculated systems, even at high drug dilution ratios. Milling or particle-size fractionation appeared to have no effect on the distribution of drug throughout the solid dispersion entrapment products. Dry blending was inferior to molecular scale drug entrapment in distributing small quantities of drug uniformly.

Chemistry, Pharmaceutical↗
PubMed1975

Effect of surface roughness and coating solvent on film adhesion to tablets.

The adhesion of a polymer film to selected tablet substrates was studied. The effect of tablet surface roughness and film-coating solvent on the adhesion of the film to the tablet was determined. A film-coating solvent having a solubility parameter close to that of the polymer was found to produce a stronger adhesional bond than a solvent having a lower surface tension. An increase in tablet surface roughness also increased film adhesion to the tablet. The adhesion was measured as the force required to peel a section of film from the tablet with a stress-strain analyzer.

Acacia↗