Typically, the drugs formulated with Captisol® are very lipophilic and are analyzed by reversed phase high performance liquid chromatography using organic solvents such as methanol or acetonitrile. Captisol® has very limited solubility in these solvents and consequently when the formulation samples are diluted directly with mobile phase, the Captisol® and/or Captisol®: drug complex may precipitate and the analysis of the sample may give erratic assay results. This may also be seen if the formulation is directly injected on the column as the precipitation may occur on-column.
The analyst should check the mobile phase compatibility with the formulation. Dilutions with intermediate solutions may be necessary to overcome these precipitation issues. In general, aqueous methanol mobile phases are more compatible with Captisol® than acetonitrile solutions. However, each condition needs to be checked.
View our easy-to-use PDF for more information on how to use Captisol®
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