Zinc(II) in saliva: determination of concentrations produced by different formulations of zinc gluconate lozenges containing common excipients.

A study of the pH of saliva produced by humans sucking hard candy lozenges containing zinc gluconate and citric acid demonstrated the probability that the formulation delivered an insignificant amount of the contained zinc as Zn2+. This could account for the negative results of several clinical studies of this lozenge and similar formulations as treatment for the common cold. Direct measurement of unbound Zn2+ in saliva from this and other zinc gluconate formulations was required to substantiate the inference from the pH study.

Liquid chromatographic determination of folic acid in multivitamin preparations.

A reversed-phase high-performance liquid chromatographic method is described for a stability-indicating assay of folic acid in multivitamin preparations. This method shows excellent recovery and precision characteristics, allows the determination of folic acid to levels of 0.1 microgram/mL, is simple to execute, and is suitable for high volume routine work.

Analytical methods for drugs in the next decade.

Today's research for new drug substances is moving toward molecules of much larger molecular weight and complexity than the small, modern drug molecules, e.g., polypeptides, interferon, slow-releasing substances, and blood and plasma components.

Reverse phase high speed liquid chromatography of antibiotics. III. Use of ultra high performance columns and ion-pairing techniques.

Improved methods for the separation and quantitation of cephalosporin, penicillin, aminoglycoside and anthracycline antibiotics are presented. The use of ultra high performance 5 micrometer phase columns combined with the added dimension of ion-pairing greatly increases the ease of separation and speed of analysis of complex antibiotic mixtures. Antibiotics in a variety of dosage forms and in fermentation broths have been examined in order to provide the maximum data on impurities to meet regulatory requirements for drug safety, purity and efficacy.

Preparation and properties of bilirubin photoisomers.

Polar photoisomers of bilirubin were formed by irradiation of bilirubin in chloroform solution in the absence of O2. Two pairs of compounds were isolated with molecular weights identical with bilirubin. One pair reverted to bilirubin in polar media and gave chemical reactions similar to bilirubin; the other pair were not reconverted into bilirubin by chemical means and gave reactions distinct from those of bilirubin.

Quantitative determination of cephalexin in cephradine by NMR spectroscopy.

An NMR method to determine quantitatively the presence of cephalexin in cephradine was developed. The method is applicable to the chemical itself as well as to capsules and oral suspension formulations. The determination is based on the NMR signal arising from the five aromatic protons of the cephalexin molecule.

Quantitative determination of chlorpromazine. HCl in tablets, spansules, injectables, and bulk chemical by nuclear magnetic resonance spectroscopy.

A nuclear magnetic resonance (NMR) procedure is described for the quantitative analysis of chlorpromazine. HCl in bulk chemical as well as in final dosage forms--tablets, spansules, and injectables. The method is based on measurement of a characteristic signal of chlorpromazine relative to an internal standard.

Reverse phase high speed liquid chromatography of antibiotics. II. Use of high efficiency small particle columns.

Improved methods for the separation and quantitation of cephalosporins, penicillins, tetracyclines and several miscellaneous antibiotics by reverse phase high speed liquid chromatography are presented. The methods have been improved significantly by the substitution of high efficiency, small particle (approximately 10 micrometer reverse phase columns in place of the previously used medium efficiency, pellicular columns. The conditions and procedures described here illustrate that considerable improvements in separation and sensitivity of detection of antibiotics are achieved.

The determination of cephradine and cephalexin by reverse phase high-performance liquid chromatography.

The application of reverse phase high-performance liquid chromatography to the separation and analysis of cephradine and cephalexin is demonstrated. The procedure has been applied to chemicals, pharmaceutical formulations and reaction solutions. The preparation of samples is simple and rapid.

Quantitative NMR analysis of a four-component mixture of phenylglycine derivatives.

A rapid, accurate, and precise NMR analytical method for the analysis of phenylglycine, dihydrophenylglycine, tetrahydrophenylglycine, and cyclohexylglycine in combination with each other was developed. The method is based on the integration of the NMR signal characteristic of each component relative to the signal from tetramethylammonium bromide, which is added as an internal standard. No prior separation of the four components is required.

Effect of phototherapy on bilirubin excretion in man and the rat.

Further evidence that the bilirubin excreted by Gunn rats during phototherapy is unconjugated is presented. The unconjugated bilirubin is not carried into bile as a water-soluble complex with rapidly excreted bilirubin derivatives, nor as a result of leakage of plasma protein into bile. Phototherapy does not augment biliary excretion of bilirubin in normal nonjaundiced rats, but does increase the concentration of conjugated bilirubin in the bile of patients with alcoholic cirrhosis, although their serum bilirubin concentrations are unaffected.

NMR spectroscopic analysis of 2-mercapto-5-methyl-1,3,4-thiadiazole in cefazolin.

A rapid, sensitive, and accurate method for the quantitative analysis of 2-mercapto-5-methyl-1,3,4-thiadiazole in cefazolin is presented. The method utilizes NMR spectroscopy and is based on the difference in the chemical shift of the methyl protons on free thiadiazole and the thiadiazole moiety of cefazolin.

Inhibition of prostaglandin synthetase and carrageenan-induced edema by tricyclic analogs of flufenamic acid.

A group of tricyclic analogs of flufenamic acid were tested for their ability to inhibit both the biosynthesis of prostaglandin and carrageenan-induced inflammation of the rat paw. All had activity greater than phenylbutazone as inhibitors of prostaglandin synthetase, with SK&F 22908 being as active as flufenamic acid. The anti-inflammatory activities of these compounds correlated only to a minor degree with the inhibition of prostaglandin biosynthesis.

Reverse phase high speed liquid chromatography of antibiotics.

Reverse phase high speed liquid chromatographic methods are presented for the separation and detection of cephalosporins, penicillins, tetracyclines and other miscellaneous antibiotics. The reverse phase approach is superior to ion-exchange liquid chromatography and spectrophotometric, chemical and microbiological procedures currently in use. In addition to being simple and easy to control, the technique is rapid, convenient and precise and provides the basis for the direct analysis of pure compounds, stability samples, complex mixtures and dosage forms of all types.

Cholesterol solubility in lecithin-bile salt systems.

The method of sample preparation can markedly influence the rate of dissolution and attainment of supersaturated states of cholesterol. The equilibrium solubility of cholesterol, studied as a function of its physical state in a model bile system, is almost half that of previously accepted values. Slow attainment of the equilibrium state may have acted to bias previous studies.