Process Design for Antisolvent Crystallization of Erythromycin Ethylsuccinate in Oiling-out System

The antisolvent coprecipitation method for enhanced bioavailability of poorly water-soluble drugs

In recent years, poorly water-soluble drug candidates in the drug development pipeline have been a challenging issue for the pharmaceutical industry. Many delivery systems such as nanocrystals, cocrystals, nanoparticles, and amorphous solid dispersions (ASDs) have been developed to overcome these problems. A large number of methods are utilized to realize the above delivery systems. Among all the preparation methods, the antisolvent coprecipitation method is a relatively simple, cost-effective method, offering many advantages over conventional methods. An overview of recent developments for each solubility enhancement approach using the antisolvent coprecipitation method is presented. This current review details a comprehensive overview of the antisolvent coprecipitation process and its properties, as well as the fundamentals for enhancing the solubility and bioavailability of poorly water-soluble drugs by nanotization, polymorph control with polymers and/or surfactants. Furthermore, this review also presents insights into the factors affecting the antisolvent coprecipitation process.

pH-Dependent-Oiling-out During the Polymorphism Transformation of Disodium Guanosine 5′-Monophosphate

Oiling-out occurs frequently in industrial crystallization, and strongly influences the morphology and quality of crystals. In this study, the influence of oiling-out with higher pH during the polymorph transformation of...

Effects of Chemical and Geometric Microstructures on the Crystallization of Surface Droplets during Solvent Exchange

In this work, we investigate the crystallization of droplets formed on micropatterned surfaces. By solvent exchange in a microchamber, a ternary solution consisting of a model compound β-alanine, water, and isopropanol was displaced by a flow of isopropanol. In the process, oiling-out droplets formed and crystallized. Our results showed that the shape and size of the crystals on surfaces with chemical micropatterns could be simply mediated by the flow conditions of solvent exchange. More uniform crystals formed on hydrophilic microdomains compared to hydrophobic microdomains or homogeneous surfaces. Varying flow rates or channel heights led to the formation of thin films with microholes, connected networks of crystals, or small diamond-shaped crystals. Physical microstructures (represented by microlenses) on the surface allowed the easy detachment of crystals from the surface. Beyond oiling-out crystallization, we demonstrated that the crystal formation of another solute dissolved in the droplets could be triggered by solvent exchange. The length of crystal fibers after the solvent-exchange process was shorter at a faster flow rate. This study may provide further understanding to effectively obtain the crystallization of surface droplets through the solvent-exchange approach.

Understanding the Reaction Crystallization Process of Glycidyl Trimethyl Ammonium Chloride

Reaction crystallization to produce glycidyl trimethyl ammonium chloride (GTA) via epichlorohydrin with gas-state trimethylamine was investigated. The crystallization process of the GTA gas-liquid reaction was optimized by a seed method. The optimized technology can prepare GTA products with crystal form and purity greater than 97%. The crystallization process of GTA consists of four steps (i.e., addition of seed, dispersion of seed, growth of crystals on the seed surfaces, agglomeration and growth of crystal). Seed method and flow rate are the key factors affecting purity. The purity and particle size of GTA crystals were satisfactory as long as the operation was kept within the defined envelope. The experiments were conducted on a 1 L reactor and successfully scaled-up to 3000 L in industry.

Optimization of the Critical Parameters of the Spherical Agglomeration Crystallization Method by the Application of the Quality by Design Approach

This research work presents the use of the Quality by Design (QbD) concept for optimization of the spherical agglomeration crystallization method in the case of the active agent, ambroxol hydrochloride (AMB HCl). AMB HCl spherical crystals were formulated by the spherical agglomeration method, which was applied as an antisolvent technique. Spherical crystals have good flowing properties, which makes the direct compression tableting method applicable. This means that the amount of additives used can be reduced and smaller tablets can be formed. For the risk assessment, LeanQbD Software was used. According to its results, four independent variables (mixing type and time, dT (temperature difference between solvent and antisolvent), and composition (solvent/antisolvent volume ratio)) and three dependent variables (mean particle size, aspect ratio, and roundness) were selected. Based on these, a 2–3 mixed-level factorial design was constructed, crystallization was accomplished, and the results were evaluated using Statistica for Windows 13 program. Product assay was performed and it was revealed that improvements in the mean particle size (from ~13 to ~200 µm), roundness (from ~2.4 to ~1.5), aspect ratio (from ~1.7 to ~1.4), and flow properties were observed while polymorphic transitions were avoided.