Preparative Separation and Structural Identification of Impurities of a New α2‑Adrenoceptor Agonist Using Stacking Injection, LC-MSn and LC-SPE-NMR

Josiane Cardoso,Tiago Venâncio,Maria Do Carmo De Lima,Sérgio Thomasi,Regina Oliveira,Ivan Pitta

doi:10.21577/0103-5053.20160259

Abstract

Identifying impurities in drug substances has become one of the most important issues in pharmaceutical analysis since it can have a significant impact on the efficacy of new pharmaceutical products. Due to the purity requirements, in this paper a new synthetic α2-adrenoceptor agonist, called LPSF-PT-31, was purified and its impurities were characterized by liquid chromatography-multistage mass spectrometry (LC-MSn) and liquid chromatography-solid phase extraction-nuclear magnetic resonance (LC-SPE-NMR). The purification step was conducted using a semi-preparative liquid chromatography and stacked injections as a new approach to drug purification. As a result, a total yield of 75% of the pure LPSF-PT-31 and 2.9 L day-1 in solvent reduction was obtained. The combination of semi-preparative stacking injection, LC-MSn, and LC-SPE-NMR, demonstrated to be efficient to purify active drugs and unambiguously identify its impurities. In addition, isolation and identification of drug impurities in the early stages of development can improve the synthetic pathway, preventing the formation of impurities or minimizing this formation to minimum levels.

Highlights

IntroductionIdentifying impurities in drug substances has become one of the most important issues in modern pharmaceutical analysis in order to achieve quality, safety and efficacy of drugs, once the presence of impurities, even in small amounts, can have a significant impact on the efficacy and toxicology of pharmaceutical products.[1,2,3,4,5] Detecting, isolating and structurally identifying impurities in drug substances and pharmaceutical formulations have been demanded by various regulatory organizations such as the Food and Drug Administration (FDA),[6] the International Conference on Harmonisation (ICH),[7] the European Medicines Agency (EMEA)[8] and the Brazilian Health Surveillance Agency (ANVISA).[9]
Apart from the LPSF-PT-31 chromatographic peak, the presence of two impurities was detected, which were denominated as impurity A and impurity B with retention time of 12 and 13 min, respectively
For both impurities A and B, the liquid chromatography (LC)-MSn analyses revealed the same protonated ion at m/z 259 and the same fragmentation pattern which suggest that these two impurities were isomers

Summary

Introduction

Identifying impurities in drug substances has become one of the most important issues in modern pharmaceutical analysis in order to achieve quality, safety and efficacy of drugs, once the presence of impurities, even in small amounts, can have a significant impact on the efficacy and toxicology of pharmaceutical products.[1,2,3,4,5] Detecting, isolating and structurally identifying impurities in drug substances and pharmaceutical formulations have been demanded by various regulatory organizations such as the Food and Drug Administration (FDA),[6] the International Conference on Harmonisation (ICH),[7] the European Medicines Agency (EMEA)[8] and the Brazilian Health Surveillance Agency (ANVISA).[9]. Bearing in mind the impact of impurities in active pharmaceutical ingredients (APIs), the ANVISA and ICH guidelines indicate that impurities at or above 0.1% in the drug substance require identification.[7,9]. In this context, the development of selective and efficient methods to isolate drug impurities is required. Preparative chromatography is an essential and conventional tool to isolate and purify compounds and it is widely used in chemical and pharmaceutical industries during the discovery and development process of new chemical entities (NCEs) to obtain a large amount of pure drugs.

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