At-line monitoring of salification process of the antiretroviral lamivudine-saccharinate salt using FT-MIR spectroscopy with multivariate curve resolution

Abstract This article presents a promising application of Fourier transform-mid infrared (FT-MIR) spectroscopy with multivariate curve resolution ― alternating least-squares (MCR-ALS) as an at-line process analytical technology (PAT) to enhancing the understanding and continuous control of a pharmaceutical manufacturing process. Its objective was to monitor the synthesis of pharmaceutical multicomponent crystals in solid-state, namely the mixture between lamivudine (active pharmaceutical ingredient-API) and saccharin (coformer) using liquid assisted grinding (LAG) in proportion of 1:1 in a ball mill. The continuous monitoring of synthesis procedure ensured product quality, revealing some of the events that can be detected during mechanochemical synthesis by FT-MIR spectroscopy with MCR-ALS. The concentration profiles retrieved by MCR-ALS allowed to identify the end of the salt synthesis. In fact, this is one of the advantages of real-time monitoring using FT-MIR spectroscopy and MCR-ALS, because it can be helpful not only to monitor and control a pharmaceutical manufacturing process, but also to optimize efficient use of energy, time and raw materials for lamivudine-saccharinate salt synthesis. Moreover, it allowed to understand that the antiretroviral lamivudine-saccharinate salt synthetized by LAG showed a fast reaction mechanism due to the presence of ethanol as catalyst. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) techniques provided additional information needed to fully characterize pharmaceutical lamivudine-saccharinate salt synthetized by LAG technique.