Changes in Test Methods for Internationalization in the Japanese Pharmacopoeia (Part 2): Establishment of a Quantitative Method for Lorazepam Using HPLC Analysis

Abstract

The Japanese Pharmacopoeia (JP) is an official normative publication that is referred to, for establishing the authenticity and properties and maintaining the quality of pharmaceutics in Japan. Partial amendments are periodically made to these guidelines to keep up with the progress of science and technology, and the international harmonization is revised every 5 years. Thus, “Internationalization of the JP” is one of the more important issues to address for the revision of the JP. For example, the incorporation of the test methods that have been used in other pharmacopeias, such as the United States Pharmacopeia (USP) and the European Pharmacopoeia (EP), into the JP is a useful approach. In light of this, we have recently reported changes in test methods in the 17th JP, “Establishment of a quantitative test method for clonidine hydrochloride from using a potentiometric titration method to using HPLC”. As a part of our ongoing research to change test methods for internationalization, we selected lorazepam. Lorazepam is analyzed using a potentiometric titration method as listed in the 17th JP; however, both the USP and EP use HPLC for quantitative analysis of this drug. In this study, we synthesized the related impurities of lorazepam listed in the USP and the EP and determined their purities using quantitative NMR. The separation conditions of these compounds, including lorazepam, were examined using HPLC and simultaneous analyses were performed. In addition, lorazepam extracted from the tablets was analyzed using conditions similar to those used for the analysis of the related impurities.