Application Note 1087: Simultaneous Determination of Amlodipine and Its Counterion Besylate by HPLC demonstrates that this method requires only 8 minutes per analysis using a column designed for pharmaceutical analysis and ultraviolet detection. In addition, combining the analysis of the active pharmaceutical ingredient (API) and counterion into a single method saves times, reduces mobile phase consumption, and minimizes waste.
Amlodipine besylate is a commonly prescribed drug product. During the drug manufacturing process, HPLC techniques are frequently used to analyze the API, but often lack the sensitivity to reliably identify the counterion. Although the current U.S. Pharmacopeia monograph for determining amlodipine besylate describes an HPLC method for separating the API, it has no method to determine the besylate counterion. Thus, this new approach gives drug manufacturers the ability to simultaneously determine both amlodipine and its counterion besylate in a single method.