The objective of this work was to delineate the contribution of thermodynamic activities of ionized and unionized species on buccal drug permeation. The flux and permeability of a model acidic (nimesulide) and basic (bupivacaine) drug were determined across porcine buccal mucosa at different pH conditions. Thermodynamic activities of ionized and unionized drug species were expressed as degree of saturation (DS) and also calculated using a modified Debye-Hückel equation. Flux of model drugs across buccal mucosa depended on pH and donor chamber concentration. For saturated solution, the DS or the relative activity of the unionized species remained constant (DS(unionized) = 1) under different pH conditions. The DS of ionized species (DS(ionized)), however, increased (nimesulide) or decreased (bupivacaine) with an increase in pH, resulting in either an increased (nimesulide) or decreased (bupivacaine) flux. On the contrary, at subsaturated drug concentrations in the donor chamber, a decrease in nimesulide flux was observed with an increase in pH due to a decrease in DS(unionized). In case of a subsaturated bupivacaine solution, DS(unionized) increased with pH, thereby increasing the flux. In conclusion, thermodynamic activities of both ionized and unionized species of a drug contribute to flux across the buccal mucosa. The ionized and unionized species contributed equally to total flux when 90% of the drug was ionized.
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Plant Mol Biol
January 2025
Department of Agricultural and Environmental Sciences, University of Milan, via Celoria 2, 20133, Milan, Italy.
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January 2025
Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Surface-active agents (surfactants) release potential energy as they migrate from one of two adjacent fluids onto their fluid-fluid interface, a process that profoundly impacts the system's energy and entropy householding. The continuum thermodynamics underlying such a surfactant-enriched binary-fluid system has not yet been explored comprehensively. In this article, we present a mathematical description of such a system, in terms of balance laws, equations of state, and permissible constitutive relations and interface conditions, that satisfies the first and second law of thermodynamics.
View Article and Find Full Text PDFEnviron Technol
January 2025
Department of Chemistry, Sathyabama Institute of Science and Technology, Chennai, India.
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January 2025
Liver and Gastrointestinal Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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Nanoscale
January 2025
Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Single atom alloys (SAAs) have gained tremendous attention as promising materials with unique physicochemical properties, particularly in catalysis. The stability of SAAs relies on the formation of a single active dopant on the surface of a metal host, quantified by the surface segregation and aggregation energy. Previous studies have investigated the surface segregation of non-ligated and ligated SAAs to reveal the driving forces underlying such phenomena.
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