Detection and Quantification of Alprostadil in Caverject by Micellar Electrokinetic Chromatography Using Reversed-Polarity Electrostacking
Stevens, Benjamin D.
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A micellar electrokinetic chromatography method was developed for detection and quantification of alprostadil and its primary degradation product in the sterile powder form of the anti-impotence drug Caverject. Reversed-polarity field-amplification and reversed-polarity electrostacking were explored as on-column concentration techniques for the anionic analytes. A nearly 40-fold response enhancement for alprostadil in the drug formulation was achieved using the optimized reversed-polarity electrostacking method. To our knowledge, there are no published quantitative applications of this technique in the scientific literatrure. The optimized method is a 15 minute assay which involves introduction of an 18 cm sample plug, which is subsequently backed almost completely out of the column. The primary components of the run buffer are sodium phosphate salts and sodium dodecyl sulfate. Method validation following the guidelines generally accepted by the pharmaceutical industry was conducted and the results are reported here. Relative standard deviations for precision tests averaging approximately 3% were obtained for both components of interest, and response linearity was also demonstrated for each component. Reconstituted samples were shown to be stable for up to 8 hours, and alprostadil was resolved from all significant degradation products and process impurities.