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.