Solubility of favipiravir (as an anti-COVID-19) in supercritical carbon dioxide: An experimental analysis and thermodynamic modeling

Predicting the solubility of drugs in supercritical carbon dioxide using machine learning and atomic contribution

The pharmaceutical sector is aware of supercritical CO2 (SC-CO2) as a possible replacement for problematic organic solvents. Using a novel artificial intelligence (AI) strategy to predict drug solubility using the SC-CO2 system mathematically has been deemed an intriguing approach. In this work, the atomic contribution (AC) method and machine learning (ML) models are combined to develop hybrid machine learning models to compute the solubility of several drugs, including anticoagulants, anti-cancers, calcium channel blockers, immunosuppressives, antihistamines, and others. The novelty of the approach lies in using the AC concept to capture molecular details at the atomic level. This enables the model to account for the specific contributions of individual atoms and to provide more precise input features for machine learning. The integration of these molecular insights with ML techniques results in significantly improved predictive performance over traditional ML methods. Throughout the modeling procedure, temperature, pressure, the density of SC-CO2, and the effect of constituent atoms of the drugs are the input variables, while the solubility of drugs is the output. This study looks into predicting the solubility of these drugs in SC-CO2 using the least square support vector machine (LSSVM) with radial basis function kernel (RBF) and multilayer perceptron artificial neural network (MLPANN). These models were developed using a database including 2358 experimental solubility data points from 86 solid drugs. The solubility of solid drugs in supercritical CO2 spans a remarkably wide range in this study, from as high as 3.9 × 10-2 to as low as 1 × 10-7. The results demonstrated that this innovative approach could estimate solid drug solubility in SC-CO2 with AARD% and R2 values of 7.20 and 0.99, respectively, under different pressure and temperature conditions. The ability of the models to capture a wide range of solubilities in SC-CO2 showcases their effectiveness in dealing with both highly and poorly soluble compounds. The developed models, considering their global prediction, accuracy, and being user-friendly, are the best options to be used by researchers for incorporating into software for enabling more efficient design of supercritical extraction processes and reducing the need for trial-and-error experimentation in manufacturing.

Preparation, and ex vivo and in vivo Characterization of Favipiravir-Loaded Aspasomes and Niosomes for Nose-to-Brain Administration

Purpose

The present study aimed to develop and compare the intranasal applicability of favipiravir-loaded aspasomes (FAV-ASPs) using film hydration method, and favipiravir-loaded niosomes (FAV-NIOs) using ethanol injection method.

Methods

The FAV-ASP and FAV-NIO formulations were characterized according to nanoparticulate characteristics (DLS, drug loading, drug encapsulation efficacy, droplet size distribution), drug release and permeability behavior.

Results

The optimized FAV-ASP formulation (FAV-ASP8) consisted of FAV, ascorbyl palmitate, Span® 60 and cholesterol (30:25:25:50 w/w) with nano-scale size range (292.06 ± 2.10 nm), narrow polydispersity index (PDI) value (0.36 ± 0.03), adequate zeta potential (-74.73 ± 3.28 mV) and acceptable encapsulation efficiency (55.33 ± 0.41%). The optimized FAV-NIO formulation (FAV-NIO9) contained FAV, Span® 60 and cholesterol (30:30:40 w/w) with nano-scale size range (167.13 ± 1.60 nm), narrow PDI value (0.07 ± 0.01), adequate zeta potential (-27.1 ± 1.24 mV) and acceptable encapsulation efficiency (51.30 ± 0.69%). FAV-ASP8 and FAV-NIO9 were suitable for spraying into the nasal cavity (droplet size distribution <200 µm). In vitro drug release and permeability studies demonstrated enhanced solubility and increased blood-brain barrier (BBB) permeability of FAV formulations, respectively. The ex vivo human nasal permeability study revealed that FAV diffusion from FAV-ASP8 was higher than from FAV-NIO9 or initial FAV. Furthermore, the in vivo animal study showed that FAV-ASP8 had a higher BBB penetration compared to FAV-NIO9 and pure FAV. The in vitro-in vivo correlation study showed good correlation between the in vitro and the in vivo pharmacokinetic data.

Conclusion

FAV-ASP8 for nose-to-brain delivery system could be a promising formulation to improve FAV bioavailability compared to FAV-NIO9.

Mesalazine solubility in supercritical carbon dioxide with and without cosolvent and modeling

In this study, the solubility of mesalazine in supercritical carbon dioxide with and without cosolvent was carried out for the first time at different temperatures and pressure values ranging from 308 to 338 K and 12 to 30 MPa, respectively. The determined experimental molar solubilities of mesalazine in supercritical carbon dioxide were in the range of 4.41 × 10-5 to 9.97 × 10-5 (308 K), 3.9 × 10-5 to 13.1 × 10-5 (318 K), 3.4 × 10-5 to 16 × 10-5 (328 K) and 3.3 × 10-5 to 18.4 × 10-5 (338 K). Meanwhile, the determined experimental molar solubilities in supercritical carbon dioxide using 2% dimethyl sulfoxide as cosolvent were in the range of 28.22 × 10-5 to 36.2 × 10-5 (308 K), 26.07 × 10-5 to 51.41 × 10-5 (318 K), 25.02 × 10-5 to 69.07 × 10-5 (328 K) and 25.86 × 10-5 to 82.6 × 10-5 (338 K). A novel association model was employed to simulate the solubility data of the binary and ternary systems. Various semiempirical correlations were utilized to calculate the solubility of mesalazine in supercritical carbon dioxide. The new association model was deemed the most superior model, achieving an average absolute relative deviation value of 4.13% without a cosolvent, and 3.36% when a cosolvent was included.

Determination of the solubility of methyldopa in supercritical carbon dioxide for drug delivery applications: thermal analysis

The production of fine particles by green technology like supercritical carbon dioxide requires the assessment of substantial solubility data at high pressures. This study represents the first determination of the solubility of methyldopa in carbon dioxide at pressures and temperatures ranging from 12 to 30 MPa and from 313.2 to 343.2 K, respectively. The mole fractions were obtained under the aforementioned conditions and ranged from 0.805 × 10⁻5 to 11.345 × 10⁻5. Four empirical models (Chrastil, Bartle et al., Mendez-Santiago, & Teja, and Kumar-Johnston) and two equations of state (Peng-Robinson and Soave-Redlich-Kwong) were used to correlate drug solubility. The K-J model demonstrated the highest accuracy, with an AARD of 8.38% and a R2 value of 0.988. Furthermore, the enthalpy values for the drug in SC-CO₂ were estimated using the Chrastil and Bartle models, resulting in values of 34.35 and 56.87 kJ·mol⁻¹, respectively. The results demonstrate that the SRK more pronounced results than the PR model, with an AARD% of 23.03 and a R2 value of 0.903 compared to 26.42 and 0.837. The article's conclusions provide a valuable reference for the application of green method in the production of fine particles of methyldopa.

Measuring and modeling the solubility of sulfasalazine in supercritical carbon dioxide to select methods for producing nanoparticles

In the present study, the solubility of sulfasalazine in carbon dioxide was investigated at temperatures ranging from 313 K to 343 K and pressures ranging from 12 to 30 MPa. The experimentally determined molar solubilities of sulfasalazine in ScCO2 were found to be in the range of 4.08 × 10- 5 to 8.61 × 10- 5 at 313 K, 3.54 × 10- 5 to 11.41 × 10- 5 at 323 K, 3.04 × 10- 5 to 13.64 × 10- 5 at 333 K, and 2.66 × 10- 5 to 16.35 × 10- 5 at 343 K. The solubility values were correlated via a number of different types of equations, such as semi-empirical correlations, the Peng-Robinson, the PC-SAFT equation, and the regular solution. Furthermore, the findings demonstrate that semi-empirical, equation of state models, and the regular solution model possess the capability of precisely determining the solubility. Moreover, the solubility magnitude suggests that the gas anti-solvent method may be a viable approach for nanoparticle production.

Advancements in Antiviral Therapy: Favipiravir Sodium in Nasal Formulation

Favipiravir (FPV) is an Active Pharmaceutical Ingredient (API) known to have lower solubility in aqueous solvents. In the current study, efforts were made to generate a crystalline Favipiravir Sodium Salt (NaFPV) for enhanced solubility in aqueous media. The in-house generated NaFPV was characterized by NMR studies and its sodium content was determined by Flame Emission Spectroscopy (FES) as a confirmation of salt formation. Its solubility was determined where-in the solubility of NaFPV in water was about 100 times greater than FVP. FPV and NaFPV nasal spray formulations were prepared and its activity was determined against human coronavirus (hCoV) 229E strain. In the anti-hCoV assay as compared to FPV, NaFPV showed almost threefold higher anti-viral activity than its unmodified counterpart. Accelerated stability and spray pattern characteristics of both the formulations were studied. Interestingly, NaFPV showed higher physical stability during storage at conditions 40 ± 2 °C/ 75% ± 5% RH. The nasal spray formulations of both FPV and NaFPV showed ideal plume geometry and spray pattern of acceptable specifications. Due to its improvement in terms of solubility, NaFPV will have higher rate and extent of absorption, and faster onset of the therapeutic effect and may appear to be a feasible alternative to regular favipiravir for use in solid dosage forms.

Improving and measuring the solubility of favipiravir and montelukast in SC-CO2 with ethanol projecting their nanonization

Supercritical carbon dioxide (SC-CO2)-based approaches have become more popular in recent years as alternative methods for creating micro- or nanosized medicines. Particularly, high drug solubility is required in those techniques using SC-CO2 as a solvent. During the most recent pandemic years, favipiravir and montelukast were two of the most often prescribed medications for the treatment of COVID-19. In this study, ethanol at 1 and 3 mol% was utilized as a cosolvent to increase the solubility of both medicines in SC-CO2 by a static approach using a range of temperatures (308 to 338 K) and pressure (12 to 30 MPa) values. The experimentally determined solubilities of favipiravir and montelukast in SC-CO2 + 3 mol% ethanol showed solubility values up to 33.3 and 24.5 times higher than that obtained for these drugs with only SC-CO2. The highest values were achieved in the pressure of 12 MPa and temperature of 338 K. Last but not least, six density-based semi-empirical models with various adjustable parameters were used to perform the modeling of the solubility of favipiravir and montelukast.

Experimental and modeling of solubility of sitagliptin phosphate, in supercritical carbon dioxide: proposing a new association model

The solubility of an anti-hyperglycemic agent drug, (R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro [1,2,4] triazolo[4,3-a] pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl) butan-2-amine (also known as Sitagliptin phosphate) in supercritical carbon dioxide (scCO2) was determined by ananalytical and dynamic technique at different temperatures (308, 318, 328 and 338 K) and pressure (12-30 MPa) values. The measured solubilities were in the range of 3.02 × 10-5 to 5.17 × 10-5, 2.71 × 10-5 to 5.83 × 10-5, 2.39 × 10-5 to 6.51 × 10-5 and 2.07 × 10-5 to 6.98 × 10-5 in mole fraction at (308, 318, 328 and 338) K, respectively. The solubility data were correlated with existing density models and with a new association model.

Solubility measurement of verapamil for the preparation of developed nanomedicines using supercritical fluid

A static method is employed to determine the solubilities of verapamil in supercritical carbon dioxide (SC-CO2) at temperatures between 308 and 338 K and pressures between 12 and 30 MPa. The solubility of verapamil in SC-CO2 expressed as mole fraction are in the range of 3.6 × 10-6 to 7.14 × 10-5. Using four semi-empirical density-based models, the solubility data are correlated: Chrastil, Bartle, Kumar-Johnston (K-J), and Mendez-Santiago and Teja (MST), two equations of state (SRK and PC-SAFT EoS), expanded liquid models (modified Wilson's models), and regular solution model. The obtained results indicated that the regular solution and PC-SAFT models showed the most noteworthy exactness with AARD% of 1.68 and 7.45, respectively. The total heat, vaporization heat, and solvation heat of verapamil are calculated at 39.62, 60.03, and - 20.41 kJ/mol, respectively. Regarding the poor solubility of verapamil in SC-CO2, supercritical anti-solvent methods can be an appropriate choice to produce fine particles of this drug.

Nasal delivery as a strategy for the prevention and treatment of COVID-19

INTRODUCTION

The upper respiratory tract is a major route of infection for COVID-19 and other respiratory diseases. Thus, it appears logical to exploit the nose as administration site to prevent, fight, or minimize infectious spread and treat the disease. Numerous nasal products addressing these aspects have been considered and developed for COVID-19.

AREAS COVERED

This review gives a comprehensive overview of the different approaches involving nasal delivery, i.e., nasal vaccination, barrier products, and antiviral pharmacological treatments that have led to products on the market or under clinical evaluation, highlighting the peculiarities of the nose as application and absorption site and pointing at key aspects of nasal drug delivery.

EXPERT OPINION

From the analysis of nasal delivery strategies to prevent or fight COVID-19, it emerges that, especially for nasal immunization, formulations appear the same as originally designed for parenteral administration, leading to suboptimal results. On the other hand, mechanical barrier and antiviral products, designed to halt or treat the infection at early stage, have been proven effective but were rarely brought to the clinics. If supported by robust and targeted product development strategies, intranasal immunization and drug delivery can represent valid and sometimes superior alternatives to more conventional parenteral and oral medications.

In vitro bio-characterization of solid lipid nanoparticles of favipiravir in A549 human lung epithelial cancer cells

Objectives

Lung cancer is a leading cause of mortality worldwide. In lung cancer treatment, nebulized solid lipid nanoparticles may be a viable drug delivery method, helping the drug reach sites of action, and improving its inhalation efficiency and pulmonary deposition. This research focused on evaluating the effectiveness of solid lipid nanoparticles of favipiravir (Fav-SLNps) in facilitating drug delivery to sites of action in lung cancer treatment.

Methods

The hot-evaporation method was used to formulate Fav-SLNps. The in vitro cell viability, anti-cancer effects, and cellular uptake activity were evaluated in A549 human lung adenocarcinoma cells treated with the Fav-SLNp formulation.

Results

The Fav-SLNps were formulated successfully. Importantly, Fav-SLNps at a concentration of 322.6 μg/ml were found to be safe and non-toxic toward A549 cells in vitro. The formulation had potential anti-proliferative properties via increasing the proportions of cells in G2/M and G0/G1 phases to 1.20 and 1.13 times those in untreated cells. Additionally, Fav-SLNp treatment significantly induced necrosis in A549 cells. Furthermore, the use of SLNps in the Fav formulation resulted in a macrophage drug uptake 1.23 times that of the free drug.

Conclusion

Our results confirmed the internalization and anti-cancer activity of the Fav-SLNp formulation in the A549 lung cancer cell line. Our findings suggest that Fav-SLNps could potentially be used as lung cancer treatment to facilitate drug delivery to sites of action in the lungs.

Supercritical Fluid Extraction from Zataria multiflora Boiss and Impregnation of Bioactive Compounds in PLA for the Development of Materials with Antibacterial Properties

In this research, the extraction with supercritical carbon dioxide (SC-CO2) and the subsequent impregnation of the extracted bioactive compounds from Zataria multiflora Boiss (Z. multiflora) into polylactic acid (PLA) films was investigated. The effects of temperature (318 and 338 K), pressure (15 and 25 MPa) and cosolvent presence (0 and 3 mol%) on the extraction yield were studied. The SC-CO2 assisted impregnation runs were carried out in a discontinuous mode at different pressure (15 and 25 MPa), temperature (318 and 328 K), and time (2 and 8 h) values, using 0.5 MPa min−1 as a constant value of depressurization rate. ANOVA results confirmed that pressure, temperature, and time influenced the extraction yield. Moreover, antioxidant activities of extracts of Z. multiflora were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. In addition, the antibacterial activities of the extracts were screened against standard strains of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results of this investigation indicated that extracts obtained from the aerial parts of Z. multiflora possessed antioxidant and antibacterial properties. The impregnated samples presented strong antibacterial activity against the selected microorganisms.