Quantitative TLC determination of epimeric ratios of 16-methyl 17-ketone oxidation products of dexamethasone and related drugs.

A TLC system sensitive enough to detect, identify, and allow quantitation of the 16-methyl alpha- and beta-epimers of 9-fluoro-11 beta-hydroxy-16-methylandrosta-1,4-diene-3,17-dione is described. These epimeric 17-ketones may be present as impurities in dexamethasone, betamethasone, or related drugs. A spectrodensitometer with a TLC scanning attachment was used, and results from densitometry compared favorably with quantitation by high-performance liquid chromatography, as was described recently. TLC was convenient in the rapid examination of drug samples for the detection and identification of epimeric 17-ketones and for the determination of the alpha to beta ratio of such epimers. Various applied photographic techniques for documenting TLC data are described.

Aspirin--a national survey V: Determination of aspirin and impurities in enteric coated tablets and suppository formulations and in vitro dissolution of enteric coated tablets.

The results of a national survey on the quality of enteric coated aspirin tablets and aspirin suppositories are presented. The tablets were analyzed for strength, salicylic acid content, in vitro dissolution rate, and related aspirin impurities. The suppositories were analyzed for strength and salicylic acid content. The methods of analysis and validation of data are also presented.

Stability study of nitroglycerin sublingual tablets.

Nitroglycerin sublingual tablets were studied over a 1-year period to determine tablet stability in terms of loss of strength, uniformity of tablets, and degradation of the drug itself. Tablets from six different firms were analyzed by a semiautomated procedure. The samples included two molded tablets and four compressed tablets, ranging in age at the time of initial assay from 40 days to over 1 year. The results indicated that there is a loss of strength of nitroglycerin tablets and that refrigeration slows down this loss. The study also indicated that these tablets were stable during the year of testing in terms of tablet uniformity and degradation of nitroglycerin.

Rapid screening of pharmaceuticals by thin-layer chromatography: analysis of essential drugs by visual methods.

A method for rapidly screening pharmaceuticals by thin-layer chromatography has been designed for use in areas with limited resources and by operators with limited training. An apparatus for performing the analysis in a plastic bag under equilibrium conditions was designed. Results can be reproduced by different operators and in different locations. The analysis can be performed without electricity or in a remote area, away from a laboratory. It is especially suited for field use in developing countries. The method is low cost, maintenance-free, fast, and reliable; it also uses limited volumes of solvents. The analyses can be performed without weighing if reference materials can be supplied in tablet form, provided the drug content is listed and only one unit is required for each analysis. All procedures were developed for the analysis of drugs from a partial list of essential drugs established by the World Health Organization. Three drugs were selected and prepared in the form of reference tablets. Comparisons with the analyses of the drugs in standard dosage forms were made by using reference tablets and primary USP standards. Comparable results were obtained, proving that the screening process can be conducted by using reference tablets and without weighing either the sample or the reference. The method has been successfully demonstrated and used in Swaziland, by high school teachers in the United States, and by personnel from the Ministry of Health in Saudi Arabia. Personnel can be trained in a short time to perform screening analysis of drugs.

Preparation of superior thin-layer chromatograms for quantitative in situ densitometry by nonequilibrated development. I. Trisulfapyrimidines: sulfadiazine, sulfamerazine, and sulfamethazine.

A method of obtaining controlled nonequilibrated horizontal plate development by employing a developing system open to room atmosphere is described and compared with other plate-developing techniques. Nonequilibrated plate development produced spot configurations with the precise physical outline and densitometric distribution needed for optical scanning.

A simple, inexpensive thin-layer chromatography method for the analysis of theophylline tablets.

A simple, low-cost thin-layer chromatography (TLC) procedure to estimate the quality of simple pharmaceuticals in tablet form is described together with easily built equipment to carry out the test in the field. The approach is demonstrated for theophylline, but can be used to assay the drug content of any tablet or to determine its dissolution or disintegration characteristics. The procedure can be used in the field without the need for any instrumentation.