Conductivity studies of suspension systems in different states of aggregation.

The electrical conductivity effects of dispersed, coagulated, and flocculated systems were investigated using sulfamerazine powder, an insoluble, hydrophobic drug to prepare the suspension systems. For the dispersed systems, a peak in conductivity was observed at a drug concentration between 5 and 15%. The critical coagulating concentration was defined as the concentration of drug at which a maximum in specific conductance was observed. At this concentration, a maximum number of charged particles were in the system. Coagulated suspensions showed higher conductance values than the dispersed systems at equivalent concentrations; however, the critical coagulating concentration value appeared to be the same. For flocculated suspensions there was an increase in conductance with drug concentration with no perceptible peak conductance value.

The performance of foreign pharmacy graduates on the National Association of Boards of Pharmacy licensure examination.

Since there is not a shortage of pharmacists, many fear that licensing foreign pharmacy graduates will create an oversupply. Boards of pharmacy are concerned with licensing qualified candidates. Until 1978, Illinois issued the national pharmacy licensure exam to foreign and U.S. graduates. The foreign graduates' scores were consistently lower. A prelicensure exam is needed to evaluate the foreign student's academic background. Foreign students could matriculate into an accredited college of pharmacy for remediation in the necessary areas.

Effects of deuteration on locomotor activity of amphetamine.

The synthesis of fully deuterated amphetamine (phenyl-2-aminopropane-d11) in which 11 deuterium atoms are bonded to carbons and two other highly deuterated analogues is described. Their toxicities and in vivo spontaneous locomotor activities in mice were examined and compared with that of the parent protioamphetamine. A significant reduction in toxicities and a decrease in spontaneous locomotor activity were observed for these highly enriched deuterated analogues, as compared to protioamphetamine.

Fluorescent probe study of sulfonamide binding to povidone.

The possibility of using a fluorescent probe technique for the study of drug-providone (I) interactions was investigated. 1-Anilino-8-naphthalenesulfonate (II) was used as the probe. Sulfanilamide, sulfacetamide, and sulfabenzamide were used as the binding competitors. Both sulfacetamide and sulfabenzamide decreased the fluorescence intensity of the I-II complex, while sulfanilamide increased the intensity. The fluorescence depression was greater with sulfabenzamide than with sulfacetamide, indicating that the former is more strongly bound to povidone. Since sulfabenzamide has a greater hydrophobic group (phenyl) than sulfacetamide (methyl), the binding of these sulfonamides to povidone is probably at least partially hydrophobic in nature. The enhanced fluorescence intensity of the I-II complex in the presence of sulfanilamide is believed to involve hydrogen bonding in which the sulfanilamide acts as an intermediary between I and II. Double reciprocal plots for the I-II and sulfonamide-I interactions were employed to obtain a binding constant of 3.2 X 10(4) M-1 for the I-II interaction. The association constants for sulfacetamide and sulfabenzamide were calculated by means of the Klotz equation to be 13.4 and 56.8 M-1, respectively. The povidone molecules appear to have 1.28 binding sites for these compounds under the experimental conditions.

Chemical and spectroscopic analysis of a phenobarbital-ephedrine complex.

A complex of phenobarbital and ephedrine was prepared and characterized. The complex was differentiated from physical mixtures of the two drugs by TLC and IR spectroscopy. NMR spectroscopy was used to verify the proportion of each drug in the complex and to confirm the existence of intermolecular binding. Mass spectrometry was employed to establish that all fragments characteristic of the individual drug entities could be isolated from the complex. Elemental analysis confirmed the chemical composition of the complex. A possible chemical structure for the complex was hypothesized on the basis of the chemical and spectroscopic data.

Biosynthesis of deuterated riboflavin: structure determination by NMR and mass spectrometry.

The riboflavin-producing fungus Eremothecium ashbyii was cultured in various growth media containing high concentrations of deuteriuj, and the product was isolated. The structures of highly deuterated riboflavin, in which at least 13 of 15 nonexchangeable hydrogens were replaced by deuterium, and fully deuterated riboflavin, in which all 15 nonexchangeable sites contained deuterium, were established by NMR and mass spectrometry. The aromatic protons (C-5 and C-8) wer partially substituted in the highly deuterated molecule. Information regarding three areas of the biosynthetic pathway within the microorganism was obtained as a result of the formation of these compounds. Extensive solvent interaction, possibly due to passage of sugar through the transaldolase-transketolase pathway, occurs during formation of the ribityl chain. Limited solvent participation takes place during formation of 6,7-dimethyl-8-ribityllumazine, the immediate precursor of riboflavin. Deuteration of the riboflavin C-6 and C-7 methyl groups indicates significant solvent exchange during the final step of the biosynthetic process.

Deviation of dielectric constant from ideality for certain binary solvent systems.

An equation was derived which relates the dielectric constant of mixtures of a binary solvent system to the mole fraction of the polar and nonpolar components of the system. The coefficients of the formula are readily calculated from the dielectric constant and the molar volume of the pure components of the binary solvent system. These calculated values are employed in graphical representations of the theoretical relationship of the dielectric constant of the binary solvent system and the mole fraction of the polar component of the solvent system. Experimental measurements are employed to demonstrate deviations from ideality.