State Simulated Intestinal Fluid Research Articles

Understanding the Impact of Lipids on the Solubilizing Capacity of Human Intestinal Fluids.

Lipids in human intestinal fluids (HIF) form various structures, resulting in phase separation in the form of a lipid fraction and a micellar aqueous fraction. Currently used fed state simulated intestinal fluids (SIF) lack phase separation, highlighting the need for a deeper understanding of the effect of these fractions on intestinal drug solubilization in HIF to improve simulation accuracy. In this study, duodenal fluids aspirated from 21 healthy volunteers in fasted, early fed, and late fed states were used to generate 7 HIF pools for each prandial state. The apparent solubility of seven lipophilic model drugs was measured across these HIF pools, differentiating between the micellar fraction and the total sample (including both micellar and lipid fractions). The solubilizing capacities of these fluids were analyzed in relation to their composition, including total lipids, bile salts, phospholipids, total cholesterol, pH, and total protein. The solubility data generated in this work demonstrated that current fed state SIF effectively predicted the average solubility in the micellar fraction of HIF but failed to discern the considerable variability between HIF pools. Furthermore, the inclusion of a lipid fraction significantly enhanced the solubility of fed state HIF pools, resulting on average in a 13.9-fold increase in solubilizing capacity across the seven model compounds. Although the average composition of the fluids was consistent with previous studies, substantial variability was observed in micellar lipid concentrations, despite relatively stable total lipid concentrations. This variability is critical, as evidenced by the strong correlations between the solubilizing capacity of the micellar fraction and its micellar lipid concentrations. Additionally, this study identified that fluctuations in bile salt concentrations and pH contributed to the observed variability in micellar lipid concentration. In summary, the influence of the lipid fraction on solubility was 2-fold: it enhanced the solubility of lipophilic drugs in the total fluid, and contributed to the variability in the solubilizing capacity of the micellar fraction.

Characterisation of colloidal structures and their solubilising potential for BCS class II drugs in fasted state simulated intestinal fluid

A suite of fasted state simulated intestinal fluid (SIF), based on variability observed in a range of fasted state human intestinal fluid (HIF) samples was used to study the solubility of eight poorly soluble drugs (three acidic drugs (naproxen, indomethacin and phenytoin), two basic drugs (carvedilol and tadalafil) and three neutral drugs (felodipine, fenofibrate, griseofulvin)). Particle size of the colloidal structures formed in these SIF in the presence and absence of drugs was measured using dynamic light scattering and nanoparticle tracking analysis.Results indicate that drug solubility tends to increase with increasing total amphiphile concentration (TAC) in SIF with acidic drugs proving to be more soluble than basic or neutral drug in the media evaluated. Dynamic light scattering showed that as the amphiphile concentration increased, the hydrodynamic diameters of the structures decreased. The scattering distribution confirmed the polydispersity of the simulated intestinal fluids compared to the monodisperse distribution observed for FaSSIF v1). There was a large difference in the size of the structures found based on the composition of the SIF, for example, the diameter of the structures measured in felodipine in the minimum TAC media was measured to be 170 ± 5 nm which decreased to 5.1 ± 0.2 nm in the maximum TAC media point. The size measured of the colloidal structures of felodipine in the FaSSIF v1 was 86 ± 1 nm. However, there was no simple correlation between solubility and colloidal size.Nanoparticle tracking analysis was used for the first time to characterise colloidal structures within SIF and the results were compared to those obtained by dynamic light scattering. The particle size measured by dynamic light scattering was generally greater in media with a lower concentration of amphiphiles and smaller in media of a higher concentration of amphiphiles, compared to that of the data yielded by nanoparticle tracking analysis.This work shows that the colloidal structures formed vary depending on the composition of SIF which affects the solubility. Work is ongoing to determine the relationship between colloidal structure and solubility.

Optimization of the encapsulation process of Cupuassu (Theobroma grandiflorum) pulp by spray drying as an alternative for the valorization of Amazonian fruits

Cupuassu (Theobroma grandiflorum) is an Amazonian fruit with high nutritional value and considerable antioxidant activity mainly due to phenolics and ascorbic acid. To preserve those compounds and their activity, the pulp of cupuassu was spray dried using inulin/maltodextrin mixtures as wall material. The process was optimized using response surface methodology (RSM) based on a central composite design, with inlet temperature (X1), inulin concentration in the wall material (X2) and wall material concentration (X3) as independent variables. Yield, moisture, water activity (aw), hygroscopicity, water solubility index (WSI), and ascorbic acid (AA) and phenolic (PC) encapsulation efficiency were studied. The fitted results (mostly second-order equations) enabled us to determine the optimal conditions of inlet temperature (185 °C), inulin concentration (44%), and wall material concentration (35%) with low predictive error and high desirability (close to 1.0). The microencapsulates with a sphere of diameter 2.16 ± 1.32 μm had a smooth surface and a low degree of agglomeration. Under simulated intestinal fluid conditions, 76.7% of ascorbic acid was released. These results suggest the great potential of the obtained cupuassu microencapsulates as a strategy for Amazonian fruit valorization.

Multidimensional analysis of human intestinal fluid composition

The oral administration of solid dosage forms is the commonest method to achieve systemic therapy and relies on the drug’s solubility in human intestinal fluid (HIF), a key factor that influences bioavailability and biopharmaceutical classification. However, HIF is difficult to obtain and is known to be variable, which has led to the development of a range of simulated intestinal fluid (SIF) systems to determine drug solubility in vitro. In this study we have applied a novel multidimensional approach to analyse and characterise HIF composition using a published data set in both fasted and fed states with a view to refining the existing SIF approaches. The data set provided 152 and 172 measurements of five variables (total bile salt, phospholipid, total free fatty acid, cholesterol and pH) in time-dependent HIF samples from 20 volunteers in the fasted and fed state, respectively. The variable data sets for both fasted state and fed state are complex, do not follow normal distributions but the amphiphilic variable concentrations are correlated. When plotted 2-dimensionally a generally ellipsoid shaped data cloud with a positive slope is revealed with boundaries that enclose published fasted or fed HIF compositions. The data cloud also encloses the majority of fasted state and fed state SIF recipes and illustrates that the structured nature of design of experiment (DoE) approaches does not optimally cover the variable space and may examine media compositions that are not biorelevant. A principal component analysis in either fasted or fed state in combination with fitting an ellipsoid shape to enclose the data results in 8 points that capture over 95% of the compositional variability of HIF. The variable’s average rate of concentration change in both fasted state and fed state over a short time scale (10 min) is zero and a Euclidean analysis highlights differences between the fasted and fed states and among individual volunteers. The results indicate that a 9-point DoE (8 + 1 central point) could be applied to investigate drug solubility in vitro and provide statistical solubility limits. In addition, a single point could provide a worst-case solubility measurement to define the lowest biopharmaceutical classification boundary or for use during drug development. This study has provided a novel description of HIF composition. The approach could be expanded in multiple ways by incorporation of further data sets to improve the statistical coverage or to cover specific patient groups (e.g., paediatric). Further development might also be possible to analyse information on the time dependent behaviour of HIF and to guide HIF sampling and analysis protocols.

The stability and in vitro digestion of curcumin emulsions containing Konjac glucomannan

Konjac glucomannan (KGM) was used to characterize the structure of the curcumin emulsions stabilized with whey protein isolate (WPI). With an increasing concentration of KGM from 0.1% to 0.3%, the fat droplet size decreased significantly (p < 0.05) with increasing KGM content. The retention of curcumin in emulsions with KGM was significantly higher (p < 0.05) than the emulsions without KGM, after heating at 85 °C for 90 min. These two emulsions showed good stability in the pH range of 2–8 in addition to pH 5. Both emulsions with/without KGM were stable at 0–80 mM salt concentration, however the curcumin emulsion with KGM was unstable at 100 mM NaCl concentration. The droplet size analysis and microscopic observations indicated that the aggregation of fat droplets in these two emulsions occurred under simulated gastric fluid (SGF) conditions with a digestion time of 10 min. There were more undigested fat droplets in the curcumin emulsion with KGM than the emulsion without KGM under simulated intestinal fluid conditions after 120 min of digestion. The addition of KGM in WPI-stabilized curcumin emulsions slowed down the release rate of free fatty acids and curcumin from the emulsion droplets. These findings indicated that KGM could be used to achieve a controlled and sustainable release of bioactive compounds from emulsions.

Survival Survey of Lactobacillus acidophilus In Additional Probiotic Bread

Bread is a popular food in the world because of its variety and convenience. Currently, studies on the adding probiotics to bread are limited due to the adverse effects of processing, such as baking temperature, aerobic environment to the probiotic bacteria. The objective of this study was to produce probiotic cream bread, in which Lactobacillus acidophilus was microencapsulated with Alginate 2% (A); Alginate 2% + maltodextrin 1% (AM); Alginate 2% + xanthan gum 0.1% (AX); and Alginate 2% + maltodextrin 1% + xanthan gum 0.1% (AMX). Microcapsules were added to the kernel, conducting encapsulation yield investigations, survival in baking, preservation of bread, and in simulated gastric fluid and simulated intestinal fluid conditions after 8 days of storage. The results showed that the addition of xanthan gum enhanced the encapsulation yield, it reached 92.9% and 92.37% in AMX and AX samples, respectively. The viability of L. acidophilus during baking was decreased by 3.64 and 3.75 Log (CFU/bread) in AMX and AM samples, compared to A and AX which were decreased by 4.75 and 4.44 Log (CFU/ bread). In SGF (Simulated Gastric Fluid) and SIF (Simulated Intestinal Fluid) conditions, the AMX microcapsules provide the best probiotic protection among the four tested carriers. The combination of xanthan gum and maltodextrin in alginate matrix, eventually leading to having dual efficiency: First, xanthan gum would act as buffers that reduce acid activity; Second, maltodextrin acting as a protective agent of L. acidophilus against high temperature as well as potential prebiotic that improve the viability of probiotic.

Mimicking regional and fasted/fed state conditions in the intestine with the mucus-PVPA in vitro model: The impact of pH and simulated intestinal fluids on drug permeability

Intestinal drug absorption following oral administration can be influenced by regional conditions (absorbing surface area, bacterial flora, motility, pH, mucus thickness) and food intake, all of which affect drug solubility and permeability. Therefore, it is crucial to assess the impact of these conditions on the drugability of drugs and formulations. In this study, the ability of the liposome-based mucus-PVPA in vitro permeability model to handle relevant intestinal pH conditions was evaluated, together with the investigation on the pH-dependent solubility and permeability profiles of five model drugs. This study additionally evaluated the impact of all commercially available versions of the fasted and fed state simulated intestinal fluids (SIFs) on the integrity of the barriers, and the permeabilities of one hydrophilic and one lipophilic compound were examined under these conditions. The model was found to be well-functioning in all tested pH conditions, and a pH-dependent trend was found for both solubility and permeability profiles for acidic and basic compounds, according to their degree of ionization. Moreover, the mucus layer and its pH-dependent viscosity particularly influenced the permeation of more lipophilic compounds. The PVPA barriers primarily maintained their functionality in the presence of the fed state SIFs, and the permeability of the two tested compounds showed to be influenced by their hydrophilicity/lipophilicity, their degree of interaction with mucus and by the bile salts and phospholipids content in the SIFs. Overall, the obtained results highlight the relevance of studying the effect that pH, mucus and SIFs have on intestinal drug absorption, and suggest the suitability of the mucus-PVPA model for such investigations.

The influence of homogenization and storage time on the viability of Lactobacillus casei and Bifidobacterium bifidumin ice cream

&#x0D; &#x0D; &#x0D; Bifidobacterium bifidum or Lactobacillus casei were added independently into ice cream with or without homogenization. The viability of probiotic bacteria during storage, in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was investigated. The results showed that the viability of Bifidobacterium bifidum and Lactobacillus casei in ice cream samples was significantly decreased during 100 days of storage. The homogenization in ice cream processing was a significant effect on the survival of L.casei and B.bifidum during frozen storage time. In addition, frozen storage time affected the viability of these strain when incubating in SGF and SIF conditions. The longer storage time, the more sensitive probiotic in SGF and SIF condition. The result also indicated, in SGF condition, the difference between homogenization and non-homogenization samples was only statistically significant (p&lt;0,05) after 100 days of storage. &#x0D; &#x0D; &#x0D;

Evaluation of the stability of pea and canola protein-based hydrogels in simulated gastrointestinal fluids

This work aims to investigate the effect of polyelectrolyte complexation (PEC) on the stability of protein–alginate hydrogels in simulated gastrointestinal fluids. The properties of two types of hydrogels based on pea protein isolates (PPI) and on canola protein isolates (CPI) were compared. The molecular structure of hydrogels was assessed by FTIR and their thermal stability was tested by DSC and TGA. The swelling capacity of hydrogels was tested in distilled water, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) without enzymes. CPI beads showed higher swelling capacity than PPI beads in all swelling media. In SIF, relatively higher swelling, an increase in volume and partial degradation were observed for all hydrogel beads. In addition, the swelling of beads in SIF was found to be dependent on PEC with chitosan. Moreover, degradation tests in SGF and SIF media with enzymes were performed to assess the effect of PEC on the stability of hydrogels. The results indicated that PEC had no influence on the stability of hydrogels in SGF but significantly delayed the degradation of hydrogel under SIF conditions. These findings suggest that PEC could be utilized to modify protein–alginate hydrogels to create matrices for prolonged release applications.

Encapsulation of Flaxseed Oil Using a Benchtop Spray Dryer for Legume Protein–Maltodextrin Microcapsule Preparation

Flaxseed oil was microencapsulated employing a wall material matrix of either chickpea (CPI) or lentil protein isolate (LPI) and maltodextrin using a benchtop spray dryer. Effects of emulsion formulation (oil, protein and maltodextrin levels) and protein source (CPI vs LPI) on the physicochemical characteristics, oxidative stability, and release properties of the resulting capsules were investigated. Microcapsule formulations containing higher oil levels (20% oil, 20% protein, 60% maltodextrin) were found to have higher surface oil and lower encapsulation efficiencies. Overall, LPI-maltodextrin capsules gave higher flaxseed oil encapsulation efficiencies (∼88.0%) relative to CPI-maltodextrin matrices (∼86.3%). However, both designs were found to provide encapsulated flaxseed oil protection against oxidation over a 25 d room temperature storage study relative to free oil. Overall, ∼37.6% of encapsulated flaxseed oil was released after 2 h under simulated gastric fluid, followed by the release of an additional ∼46.6% over a 3 h period under simulated intestinal fluid conditions.

Preparation and Characterization of Microcapsules Based on Biodegradable Polymers: Pectin/Casein Complex for Controlled Drug Release Systems

Controlled release of drugs is an important strategy to diminish the drug dose and adverse side effects. Aqueous mixtures of polysaccharides and proteins are usually unstable above a certain biopolymer concentration and phase separation occurs either because of repulsive (segregative) or attractive (associative) interactions. Herein, pectin/casein microcapsules were prepared by complex coacervation aiming at prolonged drug release. The morphological characteristics, particle size, distribution, and release kinetics of microcapsules were studied using as a model the hydrophilic drug acetaminophen. It was detected that complexation of pectin/casein particles occurs at pH values lower than 6, resulting in the formation of spherical particles after spray drying. Microcapsules had a mean diameter of 3.138 and 4.929μm without drug, and of 4.680 and 5.182μm with drug using USP and 8003 pectin, respectively. The in vitro release of acetaminophen from microcapsules was slow and the drug release mechanism was controlled by diffusion following first-order kinetics. There was greater release of acetaminophen in simulated gastric fluid than simulated intestinal fluid conditions. Concluding, the polymeric system present herein seemed to be appropriate for a prolonged release of acetaminophen throughout the gastrointestinal tract. Nevertheless, it is likely that it is a promising pectin/casein complex for lipossoluble drugs, which merits further investigation.

Evaluation of the thermal stability and digestibility of heterologously produced banana lectin

The thermal stability of recombinant mannose-specific banana lectin (rBanLec), as well as its stability under conditions of simulated gastro-intestinal fluid (SGF), was investigated. rBanLec was heterologously produced in Escherichia coli. Molecular mass of rBanLec, assessed by ESI-TOF mass spectrometry, was 15972.2 Da. Thermodynamic parameters for rBanLec denaturation, obtained by differential scanning calorimetry (DSC), revealed a transition maximum temperature ( T m) of 60.8 °C, calorimetric enthalpy ( H cal) of 136.17 kcal/mol and van’t Hoff enthalpy ( H VH) of 50.27 kcal/mol. rBanLec was stable following an incubation for 2 h in SGF, and then for 1 h, in the simulated intestinal fluid (SIF). Intact primary structure, biological and immunological reactivity of rBanLec were all preserved following treatment under SGF and SIF conditions. In conclusion, rBanLec is a good candidate for the novel bioadhesive lectin-based drug delivery systems to the gastro-intestinal tract (GIT).

An Automated Screening Assay for Determination of Aqueous Equilibrium Solubility Enabling SPR Study During Drug Lead Optimization

Aqueous solubility is one of the most critical physicochemical properties to be determined in the process of drug lead optimization. Particularly, an equilibrium solubility method is highly valuable to the study of structure property relationship (SPR), while meeting the needs of analytical sensitivity, reproducibility, and throughput. In this report, an automated solubility assay in a 96-well library format was designed and developed by means of robotic liquid handling, centrifugal separation, and HPLC-UV quantification. Requiring 1 mg of solid compound, this assay was used to determine the equilibrium solubility in three user-selected media, that is, 0.01 N HCl, phosphate buffer saline (PBS), and fasted state simulated intestinal fluid (SIF), with a throughput of up to 192 compounds a week. The assay parameters, including the equilibration time and the separation technique, were optimized to ensure that the thermodynamic solubility was measured at the presence of excess solid compound. A fast gradient HPLC method was developed with single-point on-plate calibration for each compound, followed by a customized 96-well chromatographic data analysis. The reporting solubility range was 1–200 μg/mL, appropriate for oral drug candidate selection at the stage of discovery lead optimization. Based on the test results obtained on the commercially available drugs and Amgen research compounds, this assay was considered to be equivalent to the conventional shake-flask methods. Examples were given to demonstrate that the thermodynamic solubility determined by this assay enabled the SPR study to support drug lead optimization.

Solution calorimetry as a tool for investigating drug interaction with intestinal fluid

Solution calorimetry offers a reproducible technique for measuring the enthalpy of solution (Δ sol H) of a solute dissolving into a solvent. The Δ sol H of two solutes, propranolol HCl and mannitol were determined in simulated intestinal fluid (SIF) solutions designed to model the fed and fasted states within the gut, and in Hanks’ balanced salt solution (HBSS) of varying pH. The bile salt and lipid within the SIF solutions formed mixed micelles. Both solutes exhibited endothermic reactions in all solvents. The Δ sol H for propranolol HCl in the SIF solutions differed from those in the HBSS and was lower in the fed state than the fasted state SIF solution, revealing an interaction between propranolol and the micellar phase in both SIF solutions. In contrast, for mannitol the Δ sol H was constant in all solutions indicating minimal interaction between mannitol and the micellar phases of the SIF solutions. In this study, solution calorimetry proved to be a simple method for measuring the enthalpy associated with the dissolution of model drugs in complex biological media such as SIF solutions. In addition, the derived power–time curves allowed the time taken for the powdered solutes to form solutions to be estimated.