ABSTRACT
Cation-exchange columns were found to be stable when used at high pH and high temperature for high-performance liquid chromatographic separations of carbohydrates and carbohydrate derivatives. Pulsed amperometric detection and refractive index detection were found to be suitable detection modes with these cation-exchange columns. Significant differences in carbohydrate separation selectivity were observed between cation-exchange and anion-exchange columns.
Subject(s)
Carbohydrates/isolation & purification , Chromatography, High Pressure Liquid/methods , Chromatography, Ion Exchange/methods , Hydrogen-Ion Concentration , TemperatureABSTRACT
The intrinsic potencies of two novel topical thiol ester corticosteroids, RS-85095 and RS-21314, were compared with the high potency corticosteroids clobetasol 17-propionate and fluocinonide, using human vasoconstriction assays. In these assays, four or five concentrations (0.03 to 3 mg/L) of the corticosteroids in 95% ethanol (alcohol, USP) were applied to predetermined sites on the forearm of volunteers and were occluded following evaporation of the alcohol. The responses were scored in terms of the presence or absence of vasoconstriction and the degree of vasoconstrictive intensity. No statistically significant difference was found in the intrinsic potencies of RS-85095, RS-21314, and clobetasol 17-propionate, and all three corticosteroids were significantly more potent than fluocinonide.
Subject(s)
Androstenols/pharmacology , Betamethasone/analogs & derivatives , Clobetasol/analogs & derivatives , Fluocinolone Acetonide/analogs & derivatives , Fluocinonide/pharmacology , Vasoconstriction/drug effects , Administration, Topical , Adult , Clobetasol/pharmacology , Drug Administration Schedule , Female , Humans , MaleABSTRACT
We have evaluated the application and performance characteristics of a system that utilizes potentiometric stripping analysis (PSA); an electrochemical technique recently proposed for use in the routine determination of lead in urine. Its advantages over current methods for urinary lead are its low cost and minimal requirements for sample pretreatment. We adapted the published procedure to enable the use of a single protocol over a wide lead concentration range (10-500 microgram/L). Using spiked urine pools, we found the precision and recovery to be acceptable for clinical usage over this range. A comparative study using individual spiked patient urines demonstrated good correlation with a bismuth hydroxide coprecipitation/atomic absorption (AA) procedure [Y (microgram/L, PSA) = -11 microgram/L + 1.10X (microgram/L, AA); S y times x = 32 microgram/L; Sa = 15 microgram/L; Sb = 0.08, N = 22]. Approximately 10% of the randomly chosen urines in this study exhibit negative interferences with the PSA method. However, these interferences were readily recognizable when using a standard addition technique to obtain concentrations from analytical signals, and were resolvable following either dilution with dilute acid or addition of Triton X-100. While we consider the system's performance characteristics acceptable, the length of time required for each urine lead determination (approximately 40 minutes) is a notable limitation to the routine clinical adoption of the instrument in its current configuration.
Subject(s)
Lead/urine , Potentiometry/instrumentation , Radiometry/instrumentation , Electrochemistry , Evaluation Studies as Topic , Humans , Spectrophotometry, AtomicABSTRACT
The feasibility of using mixtures of corticosteroids as a mechanism for enhancing total percutaneous absorption of drug has been investigated. The results of this study indicate that under certain conditions, mixtures of corticosteroids exhibit independent solubility, partitioning and diffusion behavior. Mixtures of three 21-esters of fluocinolone acetonide were found to penetrate excised human skin independently. The mixture flux rate was demonstrated to greatly exceed that attained with any of the component steroid esters at an equal concentration. A mixture composition containing a total steroid concentration of 0.015% was shown to produce significantly greater in vivo human vasoconstriction than any of the individual steroids at comparable concentrations. These results strongly support the potential clinical utility of certain topical corticosteroid mixture compositions.
