Mathematical Model For Release Research Articles

Development of Chlorhexidine-loaded Lipid Nanoparticles Incorporated in a Bioceramic Endodontic Sealer

IntroductionThis study aimed to assess BioRoot RCS (BR) incorporating liposomal chlorhexidine digluconate (CHX) for its antibacterial activity, drug release capacity, and physicochemical properties. MethodsDrug release of CHX liposomal formulations in combination with BR was evaluated spectrophotometrically and through mathematical release models for 30 days. A selected combination was evaluated for antimicrobial properties against Enterococcus faecalis biofilm growth on human dentin. Cytotoxicity was assessed following the ISO 10993-5:2019 standard on days 1, 3, and 7. Physicochemical properties were evaluated through setting time, Fourier transform infrared spectroscopy, solubility, contact angle, and film thickness. ResultsFrom BR, liposomal CHX released up to 7-fold higher CHX than CHX solution (P < .05), following a triphasic drug release pattern compared to the CHX solution, which followed a quasi-Fickian diffusion. BR combined with a selected liposomal CHX completely inhibited E. faecalis biofilm growth compared to the combination of BR with CHX solution and the control group (P < .05). Liposomal CHX decreased the contact angle (P < .05) and solubility but increased cytotoxicity (P < .05) of BR, staying above the ISO threshold. None of the other physicochemical characteristics tested differed from BR (P > .05). ConclusionThis liposomal formulation improved CHX release from BR, enhancing the antibacterial effectiveness. It presents a promising approach for local antibiofilm therapy in endodontics without substantially altering the physicochemical characteristics of BR.

Programmable Drug Release from a Dual-Stimuli Responsive Magnetic Metal–Organic Framework

Along with the increasing incidence of cancer and drawbacks of traditional drug delivery systems (DDSs), developing novel nanocarriers for sustained targeted-drug release has become urgent. In this regard, metal–organic frameworks (MOFs) have emerged as potential candidates due to their structural flexibility, defined porosity, lower toxicity, and biodegradability. Herein, a FeMn-based ferromagnetic MOF was synthesized from a preassembled Fe2Mn(μ3-O) cluster. The introduction of the Mn provided the ferromagnetic character to FeMn-MIL-88B. 5-Fluoruracil (5-FU) was encapsulated as a model drug in the MOFs, and its pH and H2S dual-stimuli responsive controlled release was realized. FeMn-MIL-88B presented a higher 5-FU loading capacity of 43.8 wt % and rapid drug release behavior in a tumor microenvironment (TME) simulated medium. The carriers can rapidly release loaded drug of 70% and 26% in PBS solution (pH = 5.4) and NaHS solution (500 μM) within 24 h. The application of mathematical release models indicated 5-FU release from carriers can be precisely fitted to the first-order, second-order, and Higuchi models of release. Moreover, the cytotoxicity profile of the carrier against human embryonic kidney cells (HEK293T) suggests no adverse effects up to 100 μg/mL. The lesser toxic effect on cell viability can be attributed to the low toxicity values [LD50 (Fe) = 30 g·kg–1, (Mn) = 1.5 g·kg–1, and (terephthalic acid) = 5 g·kg–1] of the MOFs structural components. Together with dual-stimuli responsiveness, ferromagnetic nature, and low toxicity, FeMn-MIL-88B MOFs can emerge as promising carriers for drug delivery applications.

Mathematical model and field application of aqueous phase trapping release

ABSTRACT Aqueous phase trapping (APT) is a kind of mechanical formation damage, which occurs in tight sandstone gas reservoirs. The occurrence of APT has a dramatically adverse effect on the productivity of gas wells due to the decrease of water saturation and gas permeability near wellbore. In this research, a spontaneous imbibition experiment was carried out. The Lucas–Washburn model was used to describe the imbibition behavior. Then, a mathematical model of release judgment conditions was established based on the imbibition model, taking the threshold pressure gradient into consideration. Finally, combined with the two-phase flow mechanism of gas and water, the release time of APT was deduced. This model was used to calculate the releasing time of APT in actual producing wells, and the difference between the actual release time and predicted release time is only 0.1%, which indicates that the model established in this paper can be applied to predicting release judgment condition and release time in tight sandstone gas reservoirs precisely. The proposed model along with the findings of this research can pave the way for the continuous development of water breakthrough wells in tight sandstone gas reservoirs.

Formulation and evaluation of metformin HCl floating microspheres

The purpose of the present investigation was the preparation and evaluation of gastro-retentive floating drug delivery system for anti-diabetic drug metformin hydrochloride that would retain the drug in stomach and continuously release the drug in controlled manner up to a predetermined time leading to improve bioavailability. The microspheres were prepared by oil-in-oil emulsion solvent evaporation technique using ethyl cellulose, methacrylic acid copolymer (Eudragit RS100, Eudragit RSPO and Eudragit RLPO). The dried floating microspheres were evaluated for percentage yield (%), actul drug content (%), drug entrapment efficiency, floating behavior, scanning electron microscopy and in vitro drug release studies. The microspheres were found spherical, porous and free flowing with a size range. Compatibility studies were performed by fourier transform infra-redand (FTIR) and differential thermal analysis (DTA) techniques. The DTA and FTIR data stated that drug and excipient were compatible. In-vitro release kinetics were studied in different mathematical release models following the zero order, Higuchi and Korsemeyer to find out the linear relationship and release rate of drug. The drug might be released by both diffusion and erosion as the correlation coefficient (R2) best fitted with Korsemeyer model and release exponent (n) was 0.45-0.89. In most cases good in vitro floating behavior was observed and a broad variety of drug release pattern was achieved by variation of the polymer which optimized to match target release profile. The developed floating microspheres of metformin hydrochloride may be used in clinic for prolonged drug release in stomach for at least 8 hrs, thereby improving the bioavailability and patient compliance.Asian J. Med. Biol. Res. December 2015, 1(3): 396-405

Surface Deposition and Coalescence and Coacervation Phase Separation Methods: In Vitro Study and Compatibility Analysis of Eudragit RS30D, Eudragit RL30D, and Carbopol-PLA Loaded Metronidazole Microspheres.

Metronidazole (MTZ) has extremely broad spectrum of protozoal and antimicrobial activity and is clinically effective in trichomoniasis, amoebic colitis, and giardiasis. This study was performed to formulate and evaluate the MTZ loaded microspheres by coacervation phase separation and surface deposition and coalescence methods using different polymers like Gelatin, Carbopol 934P, Polylactic Acid (PLA), Eudragit RS30D, and Eudragit RL30D to acquire sustained release of drug. In vitro dissolution studies were carried out in phosphate buffer (pH 7.4) for 8 hours according to USP paddle method. The maximum and minimum release of MTZ from microspheres observed were 84.81% and 76.6% for coacervation and 95.07% and 80.07% for surface deposition method, respectively, after 8 hours. Release kinetics was studied in different mathematical release models. The SEM and FTIR studies confirm good spheres and smooth surface as well as interaction between drug and polymers. Though release kinetic is uncertain, the best fit was obtained with the Korsmeyer kinetic model with release exponent (n) lying between 0.45 and 0.89. In vitro studies showed that MTZ microspheres with different polymers might be a good candidate as sustained drug delivery system to treat bacterial infections.

Characterization and Compatibility Studies of Different Rate Retardant Polymer Loaded Microspheres by Solvent Evaporation Technique: In Vitro-In Vivo Study of Vildagliptin as a Model Drug.

The present study has been performed to microencapsulate the antidiabetic drug of Vildagliptin to get sustained release of drug. The attempt of this study was to formulate and evaluate the Vildagliptin loaded microspheres by emulsion solvent evaporation technique using different polymers like Eudragit RL100, Eudragit RS100, Ethyl cellulose, and Methocel K100M. In vitro dissolution studies were carried out in 0.1 N HCl for 8 hours according to USP paddle method. The maximum and minimum drug release were observed as 92.5% and 68.5% from microspheres, respectively, after 8 hours. Release kinetics were studied in different mathematical release models to find out the linear relationship and release rate of drug. The SEM, DSC, and FTIR studies have been done to confirm good spheres and smooth surface as well as interaction along with drug and polymer. In this experiment, it is difficult to explain the exact mechanism of drug release. But the drug might be released by both diffusion and erosion as the correlation coefficient (R 2) best fitted with Korsmeyer model and release exponent (n) was 0.45–0.89. At last it can be concluded that all in vitro and in vivo experiments exhibited promising result to treat type II diabetes mellitus with Vildagliptin microspheres.

Insights into accelerated liposomal release of topotecan in plasma monitored by a non-invasive fluorescence spectroscopic method

A non-invasive fluorescence method was developed to monitor liposomal release kinetics of the anticancer agent topotecan (TPT) in physiological fluids and subsequently used to explore the cause of accelerated release in plasma. Analyses of fluorescence excitation spectra confirmed that unencapsulated TPT exhibits a red shift in its spectrum as pH is increased. This property was used to monitor TPT release from actively loaded liposomal formulations having a low intravesicular pH. Mathematical release models were developed to extract reliable rate constants for TPT release in aqueous solutions monitored by fluorescence and release kinetics obtained by HPLC. Using the fluorescence method, accelerated TPT release was observed in plasma as previously reported in the literature. Simulations to estimate the intravesicular pH were conducted to demonstrate that accelerated release correlated with alterations in the low intravesicular pH. This was attributed to the presence of ammonia in plasma samples rather than proteins and other plasma components generally believed to alter release kinetics in physiological samples. These findings shed light on the critical role that ammonia may play in contributing to the preclinical/clinical variability and performance seen with actively-loaded liposomal formulations of TPT and other weakly-basic anticancer agents.

Synthesis, Characterization and Kinetic Release Profile of Iron Containing Polymeric Co-conjugates with Antiproliferative Activity

In this research, the incorporation of ferrocenecarboxyaldehyde, 3-ferrocenylprop-2-enal and acetylferrocene to a polymeric backbone via hydrazone bond to form conjugates and co-conjugates was demonstrated. The conjugates and co-conjugates containing bioactive agents were characterized by nuclear magnetic resonance spectroscopy, Fourier transform spectroscopy and UV–visible Spectroscopy. Kinetic release studies of 3-ferrocenylprop-2-enal and acetylferrocene from the polymeric carriers was performed using various mathematical release models. The mechanism of release of ferrocenylpropenal and acetylferrocene followed Korsmeyer-Peppas release profile with a diffusion coefficient of n > 5 at selected pH values indicating anomalous (non‐Fickian) diffusion.

A numerical treatment of the release of drug in nonswelling transdermal drug-delivery devices

The work in this paper concerns the numerical study of controlled release of drug from porous, nonswelling transdermal drug-delivery devices to a perfect sink. A general mathematical model of release of drug is considered as a nonlinear system of partial differential equations. Two numerical procedures based on finite differences method and the Levenberg–Marquardt method are proposed to solve this model numerically. To show the ability of the proposed methods, two test cases are investigated.

A mathematical model for release of biologics from porous hollow fibers

The application of porous hollow fibers has recently been extended to the controlled release of biologics such as protein growth factors and lipid angiogenesis promoters. Release of these materials tends to occur more rapidly than would be predicted by conventional diffusion-based models of controlled release. Analysis of other modalities of transport as well as structural analysis of the controlled release system itself was performed to provide insight into the observed controlled release behavior from such systems. Specifically, it was discovered that osmotic-driven processes play a significant role in controlled release of proteins including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). It was also found that the fiber pore microstructure and (more importantly) macrostructure influences release behavior. Model-guided design was implemented to adjust the physical properties of the fiber wall, leading to a release system that is better able to sustain the delivery of VEGF. This model may be used to more easily achieve a desired complex release behavior when used in combination with external regulation of the reservoir.

Drug-Carrying Amino Silane Coated Magnetic Nanoparticles as Potential Vehicles for Delivery of Antibiotics

Drug carrying amino silane coated magnetic nanoparticles were synthesized and used as a flexible magnetic targeted delivery of antibiotics. Magnetic nanoparticles were prepared by chemical co-precipitation method and the surfaces were coated by 3-aminopropyletriethoxy silane. The characteristics of the nanoparticles were examined by Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), elemental analysis, and Fourier Transform Infrared (FTIR). TEM shows the average size of 8.6 nm in diameter for modified nanoparticles, XRD confirms the formation of nanoparticles, elemental analysis indicates that amino silane molecules have been bond onto the surface of the nanoparticles and FTIR spectra confirm that APTES and the drugs were bond onto the surface of the nanoparticles. Drug delivery behavior of the amino silane coated MNPs was studied by selecting ofloxacin and ciprofloxacin as model drugs. Effects of pH and temperature on the release of the drugs were studied. The drug loading efficiency was found 93.4 and 91.1 % for ofloxacin and ciprofloxacin, respectively. Release kinetics of both drugs showed that at pH 5.5 approximately 22% and 27.13% were released while at pH 7.2 releases occur with nearly 81.7 % and 98.78 % for ofloxacin and ciprofloxacin, respectively. In order to evaluate the release kinetics and mechanism of the drugs, different mathematical release models were applied to the released data at pH 7.2. The data was best fitted to the first-order and Higuchi an equations for ciprofloxacin and ofloxacin respectively, which revealed diffusion controlled and Fickian transport.

Comparative Evaluation of Mathematical Models for Release of Antioxidant from Chitosan Films Prepared by Different Drying Methods

Antioxidants are often added to many types of food packagings, especially packaging films, to enhance their effectiveness in protecting food from the environment. This positive action is possible due to release of the agents from the film matrix into food to reduce oxidation, thus extending the product's shelf life. For effective design of antioxidant-added films, the release characteristics of antioxidant from the films under various conditions need to be known and predicted. The aim of this study was to compare various simple mathematical models for prediction of the release of antioxidant from edible chitosan films into distilled water at room temperature. Chitosan films were prepared via hot air drying, vacuum drying, and low-pressure superheated steam drying. Models with different expressions for the effective diffusion coefficient were tested. The model equations were solved numerically using COMSOL Multiphysics software (Comsol AB, Stockholm, Sweden). The prediction efficiency of the models was verified by comparing the predicted release kinetics of the antioxidant, in terms of the total phenolics content (TPC), with the experimental data available in the literature. It was found that the model assuming the effective diffusion coefficient as a function of the phenolics concentration gave the best agreement with the experimental results.

Mathematical model for release of compounds from kerogen and its applications for Neogene sediments of the Shinjo basin, Japan

Mathematical model for release of compounds from kerogen and its applications for Neogene sediments of the Shinjo basin, Japan

Theory of emanation thermal analysis: VI. mathematical model of inert gas release from a two-phase solid-fluid system under its interface and diffusivity changes due to a chemical reaction

A mathematical model of the release of inert gas from a two-phase system with changing solid-particle surfaces; the overall diffusivity changes of the system arising from chemical reaction are also given. The explicit form of the model is derived from the emanation rate from surface labeled calcium silicates during their hydration. Emanation curves under the assumption of the Pommersheim-Clifton model of hydration kinetics are simulated on a computer and good agreement with experimental results is demonstrated for the hydration of powdered tricalcium silicate.