betadex and tipredane

Two LC assays were developed using urea-solubilized beta-cyclodextrin (beta-CD) as a mobile phase additive in combination with reversed-phase columns. A methylsilane column gave optimal resolution of the steroid tipredane from its epimer. An investigation of the effects of beta-CD concentration, column temperature, column type, and addition of ethanol on the chromatographic separation is detailed. The enantiomer and diastereoisomers of L-cis-phenylthioproline were best resolved by urea-solubilized beta-cyclodextrin and a trimethylsilane column. The elution order of L-cis-phenylthioproline relative to its stereoisomers was reversed after adding ethanol to the beta-CD containing mobile phase or by changing from a beta-CD to an acetylated beta-CD column. The resolution factors for these separations obtained using the beta-CD mobile phase were larger than those obtained using beta-CD columns. Mobile phases containing up to 0.15 M beta-CD and 8 M urea were investigated. The separation of these isomers are dramatically affected by column polarity.

Topics: Administration, Topical; Androstadienes; Anti-Inflammatory Agents; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Cyclodextrins; Isomerism; Proline