Capillary gas chromatographic-electron-capture assay for the aldose reductase inhibitor imirestat in lens and plasma.

A sensitive and selective gas chromatographic-electron-capture assay was developed for the determination of the aldose reductase inhibitor imirestat in lens and plasma. The method involves solid-phase extraction of drug and internal standard from the plasma specimen or lens sample homogenate using "Baker"-10 SPE extraction columns followed by derivatization with pentafluorobenzyl bromide and further purification. Derivatives of drug and internal standard were separated on a fused-silica capillary column and analyzed using a 63Ni electron-capture detector.

A bioavailability comparison in rabbits of two steroids formulated as high-viscosity gels and reference aqueous preparations.

In order to assess the bioavailability of steroids from a high-viscosity gel, rabbit cornea and aqueous humor levels were measured over 12 hr following topical instillation of a gel and reference preparation. Concentrations associated with a 1% tritiated prednisolone acetate gel were found to be approximately four times larger than those of the reference preparation. A graphical comparison of the 1% tritiated prednisolone sodium phosphate data showed the area under corneal and aqueous time curves to be five and 10 times greater, respectively, with the gel than data associated with the reference preparation.

Chloramphenicol in aqueous humor after topical application.

Chloramphenicol 0.5% ophthalmic solution was applied topically to patients at various times before cataract surgery. The aqueous humor was obtained at the time of surgery and analyzed for chloramphenicol content by thin-layer chromatography.

Biosynthesis of streptococcal cell walls: N-acetyl-D-muramic acid.

Glucose-1-(14)C and acetylglucosamine-1-(14)C were added singly and together with equal amounts of the unlabeled reciprocal to Brain Heart Infusion and used for the culture of Streptococcus pyogenes. The labeling pattern of the rhamnose, glucosamine, and muramic acid in the cell wall supported an intermediary role for acetylglucosamine in providing the C1-C6 moiety of muramic acid. Although radioactivity in the C2-C9 portion of muramic acid suggested that some of the lactyl group (C7-C9) came from glycolytic products, there was also considerable contribution to it from noncarbohydrate sources.