Engineering of Amorphous Active Pharmaceutical Ingredients by Sonoprecipitation and Spray Drying Pre-and Post-Processing Pharmaceutical Characterisation. Pre- and Post-Processing Physicochemical and Micromeritic Characterisation of Active Pharmaceutical Ingredients

Abstract

Amorphous active pharmaceutical ingredients remain in the research focus as an avenue to achieve a better solubility of drugs. Several processing techniques are applied to produce amorphous materials. Main two approaches applied to production of amorphous phases are comminution of crystalline materials in order to break down molecular long-range order of their crystal lattices and amorphous phase precipitation from solutions. This thesis is focused on processing challenges in preparation of amorphous API phases from solutions by spray drying and evaporative antisolvent sonoprecipitation. Budesonide (BUD) and simvastatin (SMV) were used as model poorly soluble APIs. Amorphous phases of relatively low-glass transition (Tg) APIs are physically unstable and crystallise upon storage and/or processing conditions. To tackle this issue, for the first time in this work a selection of polyvinylpyrrolidone vinyl acetate (PVP-VA) co-polymers has been applied to investigate impact of sonoprecipitation processing parameters and a composition of PVP-VA on physicochemical and micromeritic properties of BUD/PVP-VA nanoparticulate composites. Studies confirmed that in solid-state BUD is miscible with PVP-VA polymers. Application of factorial design revealed that processing parameters: polymer type, surfactant concentrations, time and amplitude of sonication impact the entrapment efficiency, drug loading, polydispersity and particle size properties of produced nanoparticles. The largest fraction of polymer to drug in produced nanoparticles has been achieved with PVP VA E-535. As it is known that polymer content in formulation of APIs may slow down its dissolution, novel approach to processing and dissolution enhancement of amorphous composites of SMV produced by spray drying has been applied. Introduction of easily crystallising inorganic salt- sodium chloride into spray drying feed rendered SMV-polyvinyl pyrrolidone (PVP) amorphous microparticles loaded with nanocrystalline NaCl. Addition of NaCl successfully facilitated generation of discrete microparticles post spray drying with low-Tg polymers, which otherwise were not processable as binary mixtures. In addition, NaCl content aided tabletability and dissolution of amorphous API composites with more viscous and high-Tg PVP polymers. Studies confirmed that application of factorial design facilitates robust design of production process of amorphous nanocomposites by sonoprecipitation as well as that introduction of soluble nanocrystalline phase into amorphous binary solid dispersion by spray drying aids its processing and dissolution.