Deep eutectic solvents (DES) have an emerging scientific role, assisting modern pharmaceutics. They are uniquely supporting the resolution of crucial issues, such as the effective extraction and isolation of bio-actives. They act as media and catalysts for pharmaceutical drug synthesis, and as green solvents and modifiers in pharmaceutical analysis. Their role in pharmaceutical formulation and drug delivery is also up-and-coming, for instance, as alternative drug-solubilizing agents, drug stabilizers and functional additives, as therapeutic deep eutectic solvents, deep eutectic API, and monomers and reaction media for the synthesis of biomaterials for advanced drug delivery. The DES also help transforming medicinal/pharmaceutical chemistry. Although DES were described in 1918, their first pharmaceutical use is only reported in 1960. In view of their broad applicability in pharmaceutics, it may be interesting to review their history, origin, evolution, potential advantages, limitations, and specific applications as green solvents. A chronological and comparative study of the literature showed the important role of DES in green approaches for modern pharmaceuticals. The concepts, applications, and outcomes of DES in pharmaceutical analysis, formulation/drug delivery, and pharmaceutical/medicinal chemistry are presented. A comprehensive outline of the atypical applications of DES as effective green solvents in pharmaceutical bioactive extraction was assessed. Efforts to present classifications of DES explored in pharmaceuticals were also made. The present manuscript also covers computational trend, adds on commercial aspects with potential future applications of DES in pharmaceutical sciences.
Intranasal drug delivery is a promising non-invasive method for administering both local and systemic medications. While previous studies have extensively investigated the effects of particle size, airflow dynamics, and deposition locations on deposition efficiency, they have not focused on the thickness of deposited particles, which can significantly affect drug dissolution, absorption and therapeutic efficacy. This study investigates the deposition patterns of dry powder particles within the nasal airway, specifically examining how factors such as flow rates, particle size, and particle cohesiveness influence deposition patterns and their thickness. Using optical coherence tomography (OCT), this study assessed the deposition behaviour of three different lactose powders in a reconstructed nasal airway model at three key anatomical locations under varying flow rates (15, 35 and 55 L/min). Computational fluid dynamics (CFD) simulations were conducted to complement the experimental data, demonstrating the airflow dynamics in the nasal airway and highlighting recirculation zones that impact deposition patterns. The results revealed that the anterior section of the nasal airway is particularly effective at capturing particles, with localised flow patterns playing a critical role in particle accumulation. These flow patterns, combined with particle size and cohesiveness, are key factors in determining where and how particles cluster, leading to thicker deposition in specific areas of the nasal airway. This study addresses the gap in understanding how these factors influence deposition thickness and spatial distribution, ultimately contributing to the optimisation of nasal drug delivery systems.