Solid Lipid Microparticles by Spray Congealing of Water/Oil Emulsion: An Effective/Versatile Loading Strategy for a Highly Soluble Drug

Prilling of crystallizable water-in-oil emulsions: Towards co-encapsulation of hydrophilic and lipophilic active ingredients within lipid microparticles

Multiparticulate drug delivery systems offer advantages in controlled release, dose flexibility, and personalized medicine. Fusion prilling, a process that produces spherical lipid-based microparticles through vibrating nozzles, is gaining interest in the field. This study aims to explore the use of fusion prilling to encapsulate crystallizable water-in-oil emulsions, enabling the incorporation of hydrophilic active pharmaceutical ingredients (APIs) within lipid matrices. Urea (highly water-soluble) and Erythromycin (poorly water-soluble) were selected as model compounds, solubilized in the aqueous and lipid phases, respectively. The first phase of the study evaluated lipid excipients for their suitability in prilling, ensuring microparticle consistency in shape, size, and stability. The second phase focused on characterizing microparticles notably in terms of structural organization and integrity. Results demonstrated successful encapsulation of both model compounds, with high efficiency, by omitting an additional emulsification step. Despite concerns over water evaporation during processing, microparticles remained stable for up to 14 months when stored at room temperature in a hermetically sealed container. This work highlights the potential of fusion prilling for multiparticulate drug delivery systems, even for formulating APIs with different solubility profiles. Future research should focus on optimizing the process for broader API incorporation.

Chitosan for improved encapsulation of thyme aqueous extract in alginate-based microparticles

Ionotropic gelation is a low-cost, easy and green microencapsulation technique. However, the encapsulation of highly soluble compounds is challenging because of the wide loss of material into the external water phase by passive diffusion and the consequent low encapsulation efficiency. In this work an important increase of encapsulation efficiency for Thymus vulgaris L. aqueous extract in alginate-based microparticles has been obtained. A formulation with the proper thyme extract/alginate ratio (30:70) was used as reference and then optimized by adding different co-carrier excipients. Microparticles obtained by dropping a solution containing thyme extract and alginate into a chitosan/calcium-chloride/acid acetic solution lead to a high encapsulation efficiency (70.43 ± 5.28 %). After drying, microparticles had a particle size of 1096 ± 72 μm, 20.087 ± 1.487 % of extract content, 6.2 % of residual water, and showed a complete release of thyme extract within one hour. Combining alginate and chitosan as polymeric co-carrier was a valuable option for efficiently encapsulating an aqueous extract by ionotropic gelation.

Microparticles and multi-unit systems for advanced drug delivery

Microparticles have unique benefits in the formulation of multiparticulate and multi-unit type pharmaceutical dosage forms allowing improved drug safety and efficacy with favorable pharmacokinetics and patient centricity. On the other hand, the above advantages are served by high and well reproducible quality attributes of the medicinal product where even flexible design and controlled processability offer success as well as possible longer product life-cycle for the manufacturers. Moreover, the specific demands of patients can be taken into account, including simplified dosing regimens, flexible dosage, drug combinations, palatability, and ease of swallowing. In the more than 70 years since the first modified-release formulation appeared on the market, many new formulations have been marketed and many publications have appeared in the literature. More unique and newer pharmaceutical technologies and excipients have become available for producing tailor-made particles with micrometer dimensions and beyond. All these have contributed to the fact that the sub-units (e.g. minitablets, pellets, microspheres) that make up a multiparticulate system can vary widely in composition and properties. Some units have mucoadhesive properties and others can float to contribute to a suitable release profile that can be designed for the multiparticulate formula as a whole. Nowadays, there are some available formulations on the market, which are able to release the active substance even for several months (3 or 6 months depending on the type of treatment). In this review, the latest developments in technologies that have been used for a long time are presented, as well as innovative solutions such as the applicability of 3D printing to produce subunits of multiparticulate systems. Furthermore, the diversity of multiparticulate systems, different routes of administration are also presented, touching the ones which are capable of carrying the active substance as well as the relevant, commercially available multiparticle-based medical devices. The versatility in size from 1 µm and multiplicity of formulation technologies promise a solid foundation for the future applications of dosage form design and development.