Analysis of modes of drug loading in silica aerogels from supercritical CO2 solutions

Singh, Neha; Mukhopadhyay, Mausumi; Vinjamur, Madhu

doi:10.1016/j.supflu.2019.104553

Cited by 8 publications

(8 citation statements)

References 23 publications

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“…This solution diffused into the aerogels, and the drug adsorbed on the surface of aerogels. In our earlier studies, it was established that in our present experimental set-up of 500 mL vessel, 8 h was a sufficiently long contact time for attaining near-equilibrium loading of drugs; beyond this time, there was no significant increase in the loading …”

Section: Methodsmentioning

confidence: 60%

“…However, the vessel was not flushed with scCO 2 and the system was depressurized after 8 h of contact time, to the ambient condition in about 20 min. During the pressure release without flushing, the residual drug in scCO 2 would precipitate both inside the pores and on the outside surface of aerogels . After depressurization, the loaded aerogel samples were kept in the desiccator at room temperature for 12 h and then weighed separately in an analytical balance.…”

Section: Methodsmentioning

confidence: 99%

“…A mathematical model developed earlier by us has been employed for the analysis of thermodynamics and kinetics of the depressurization process to ascertain precipitation of all three drugs under all conditions of depressurization studied in this work. The model is described elsewhere . Briefly, the model takes the measured pressure and temperature conditions during depressurization as inputs.…”

Section: Mathematical Model For Precipitation During Depressurizationmentioning

confidence: 99%

“…In our earlier studies, it was established that in our present experimental set-up of 500 mL vessel, 8 h was a sufficiently long contact time for attaining near-equilibrium loading of drugs; beyond this time, there was no significant increase in the loading. 25 After 8 h of contact time, the vessel was flushed with pure scCO 2 whose volume was three times the volume of the vessel. The flushing ensures that the scCO 2 −drug solution is almost completely replaced by pure scCO 2 , under the same temperature and pressure conditions as of the loading process.…”

Section: ■ Introductionmentioning

confidence: 99%

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Insights into Adsorptive Drug Loading on Silica Aerogels from Supercritical CO₂

2022

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This work gives an insight into the process of adsorptive drug loading in silica aerogels from supercritical CO2 (scCO2). A prevalent method for such loading entails bringing the aerogels into contact with the drug–scCO2 solution followed by slow or isothermal depressurization. Our previous work established that drug precipitates during depressurization. Consequently, the adsorptive drug loading measured by the prevalent method includes precipitation. An alternative method is presented for accurate measurement of adsorption avoiding precipitation. To illustrate the disparity between the two methods, the concentration dependence of drug loadings in scCO2, obtained by both methods, is compared for fenofibrate, ibuprofen, and benzoic acid. A mechanism is proposed, and a mathematical model is developed for comparing the adsorptive drug loadings by both methods. The loading obtained by the present method is found to be much less than that by the prevalent method, though both correlate well with the formalism of the Langmuir adsorption equation with the same equilibrium constant at low concentrations. Equations are developed for the concentration dependence of drug loadings measured by both methods at all concentrations in scCO2.

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Section: Methodsmentioning

confidence: 60%

Section: Methodsmentioning

confidence: 99%

Section: Mathematical Model For Precipitation During Depressurizationmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Insights into Adsorptive Drug Loading on Silica Aerogels from Supercritical CO₂

2022

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“…The maximum amount reflects the maximum possible amount of the active substance at given process parameters, which is obtained when equilibrium is reached. The maximum amount depends on the external parameters of the supercritical adsorption process, the type of substance used, and the aerogel used, which is confirmed by studies of the impregnation of active substances into aerogels, which are presented in the literature [ 5 , 10 , 11 , 12 , 13 , 14 ]. Thus, it is clear that supercritical adsorption is a complex process that includes many phenomena and its study seems relevant.…”

Section: Introductionmentioning

confidence: 73%

Experimental Investigation and CFD Modeling of Supercritical Adsorption Process

2020

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The kinetics of the supercritical adsorption process was experimentally studied by the example of ”ibuprofen-silica aerogel” composition obtainment at various parameters: Pressure 120–200 bar and temperature 40–60 °C. Computational Fluid Dynamics (CFD) model of the supercritical adsorption process in a high-pressure apparatus based on the provisions of continuum mechanics is proposed. Using supercritical adsorption process kinetics experimental data, the dependences of the effective diffusion coefficient of active substance in the aerogel, and the maximum amount of the adsorbed active substance into the aerogel on temperature and pressure are revealed. Adequacy of the proposed model is confirmed. The proposed mathematical model allows predicting the behavior of system (fields of velocity, temperature, pressure, composition, density, etc.) at each point of the studied medium. It makes possible to predict mass transport rate of the active substance inside the porous body depending on the geometry of the apparatus, structure of flow, temperature, and pressure.

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