An optimized probucol microencapsulated formulation integrating a secondary bile acid (deoxycholic acid) as a permeation enhancer

Exploring delivery systems for targeted nanotechnology-based gene therapy in the inner ear

Hearing loss places a significant burden on our aging population. However, there has only been limited progress in developing therapeutic techniques to effectively mediate this condition. This review will outline several of the most commonly utilized practices for the treatment of sensorineural hearing loss before exploring more novel techniques currently being investigated via both in vitro and in vivo research. This review will place particular emphasis on novel gene-delivery technologies. Primarily, it will focus on techniques used to deliver genes that have been shown to encourage the proliferation and differentiation of sensory cells within the inner ear and how these technologies may be translated into providing clinically useful results for patients.

Probucol-bile acid nanoparticles: a novel approach and promising solution to prevent cellular oxidative stress in sensorineural hearing loss

The use of antioxidants could thus prove an effective medication to prevent or facilitate recovery from oxidative stress-induced sensorineural hearing loss (SNHL). One promising strategy to prevent SNHL is developing probucol (PB)-based nanoparticles using encapsulation technology and administering them to the inner ear via the established intratympanic route. The preclinical, clinical and epidemiological studies support that PB is a proven antioxidant that could effectively prevent oxidative stress in different study models. Such findings suggest its applicability in preventing oxidative stress within the inner ear and its associated neural cells. However, several hurdles, such as overcoming the blood-labyrinth barrier, ensuring sustained release, minimising systemic side effects and optimising targeted delivery in the intricate inner ear structures, must be overcome to efficiently deliver PB to the inner ear. This review explores the background and pathogenesis of hearing loss, the potential of PB in treating oxidative stress and its cellular mechanisms, and the obstacles linked to inner ear drug delivery for effectively introducing PB to the inner ear.

Pharmacological effects of novel microvesicles of basil, on blood glucose and the lipid profile: a preclinical study

Microencapsulation represents a process that can create targeted, controlled release kinetics of drugs, thus optimizing therapeutic efficacy. Our group has investigated the impact of this technology on Wistar rats to determine pharmacological efficacy of basil extracts. Animals were treated with water extract of Ocimum basilicum in microvesicles and with combination of basil extracts and 3α,7α-dihydroxy-12-keto-5-cholanate, also known as 12-monoketocholic acid (MKC) acid in microvesicles for 7 days. Alloxan was used to induce hyperglycemia. Pharmacological effects on glycemia were evaluated by measuring blood glucose levels in alloxan-induced diabetic rats. Microvesicles were prepared using the Büchi-based microencapsulating system developed in our lab. The dose of basil extract that was orally administered in rats was 200 mg/kg and the dose of MKC acid was 4 mg/kg as per established protocols. A seven-day treatment with basil aqueous extract, as well as a combination of basil and MKC acid extract in the pharmaceutical formulation, led to a statistically significant reduction in the blood glucose concentration of animals with alloxan-induced hyperglycemia compared to pre-treatment values (p < 0.05 and p < 0.01), which indicates that basil has hypoglycemic and antihyperglycemic effects. Microvesicles, as a pharmaceutical-technological formulation, substantially enhance the hypolipidemic action of basil extract with MKC acid.

The Effects of Primary Unconjugated Bile Acids on Nanoencapsulated Pharmaceutical Formulation of Hydrophilic Drugs: Pharmacological Implications

Introduction

In a recent study, in our laboratory, primary unconjugated bile acids, commonly found in humans, chenodeoxycholic acid (CDCA), have been shown to improve stability of nanoencapsulated lipophilic drugs and improve their release profile after oral administration likely via electrokinetic stabilisation. Hence, this study aimed to examine the effects of CDCA on exerting similar effects on hydrophilic drugs.

Methods

Various CDCA-based formulations were produced for the orally administered hydrophilic drug, metformin. Analyses of these formulations included electrokinetic potentials, topography, drug and CDCA formulation contents, nano size distribution, heat-induced deformation and outer-core expansion indices, release profiles, shell-resistance ratio, and thermal and chemical indices. With the drug’s main target being pancreatic beta-cells, the formulations’ effects on cell viability, functions and inflammatory profiles were also investigated.

Results and Conclusions

CDCA-based metformin formulations exhibited improved stability and release profiles via thermal, chemical and electrokinetic effects, which were formulation-dependent suggesting potential applications of CDCA in the oral targeted delivery of hydrophilic drugs.

Polyelectrolytes Formulated with Primary Unconjugated Bile Acid Optimised Pharmacology of Bio-Engineered Implant

Introduction. Several studies have shown that different biomaterials and hydrogels comprising various bile acids such as chenodeoxycholic acid (CDCA), as well as excipients such as poly-(styrene)-sulphonate (PSS) and poly-(allyl)-amine (PAA), exhibited positive biological effects on encapsulated viable pancreatic β-cells. Hence, this study aimed to investigate whether incorporating CDCA with PSS and PAA will optimise the functions of encapsulated pancreatic islets post-transplantation in Type 1 diabetes (T1D). Methods. Mice were made T1D, divided into two equal groups, and transplanted with encapsulated islets in PSS-PAA (control) or with CDCA-PSS-PAA (treatment) microcapsules. The effects of transplanted microcapsules on blood glucose, inflammation and the bile acid profile were measured post-transplantation. Results and Conclusion. Compared with control, the treatment group showed better survival rate, improved glycaemic control, and lower inflammatory profile, illustrated by ↓ interleukin 1-β, interleukin-6, interleukin-12, and tumour-necrosis factor-α, and ↓ levels of the bile acid, as well as lithocholic acid in the plasma, liver, large intestine and faeces. The results suggest that CDCA incorporation with PSS-PAA microcapsules exerted beneficial effects on encapsulated islets and resulted in enhanced diabetes treatment, post-transplantation, at the local and systemic levels.

The Effects of Accelerated Temperature-Controlled Stability Systems on the Release Profile of Primary Bile Acid-Based Delivery Microcapsules

Introduction: Bile acid-based drug encapsulation for oral delivery has been recently explored in our laboratory and has shown to be beneficial in terms of drug-targeted delivery and release profile, but stability at various temperatures has not previously been examined; hence, this is the aim of this study. Methods: Various types of bile acid-based microcapsules containing the drug metformin were produced and tested for accelerated temperature-controlled profiles, as well as morphology, elemental composition, drug content, resilience, floatability, wettability and release profiles at various pH values. Results: Accelerated temperature-controlled analysis showed negligible effects on morphology, size, or shape at very low temperatures (below 0 °C), while higher temperatures (above 25 °C) caused alterations. Drug contents, morphology and elemental composition remained similar, while wettability and the release profiles showed formulation-dependent effects. Discussion and Conclusion: Results suggest that bile acid-based microcapsules containing metformin are affected by temperature; hence, their shelf life is likely to be affected by storage temperature, all of which have a direct impact on drug release and stability profiles.

Chenodeoxycholic Acid Pharmacology in Biotechnology and Transplantable Pharmaceutical Applications for Tissue Delivery: An Acute Preclinical Study

INTRODUCTION

Primary bile acids (PBAs) are produced and released into human gut as a result of cholesterol catabolism in the liver. A predominant PBA is chenodeoxycholic acid (CDCA), which in a recent study in our laboratory, showed significant excipient-stabilizing effects on microcapsules carrying insulinoma β-cells, in vitro, resulting in improved cell functions and insulin release, in the hyperglycemic state. Hence, this study aimed to investigate the applications of CDCA in bio-encapsulation and transplantation of primary healthy viable islets, preclinically, in type 1 diabetes.

METHODS

Healthy islets were harvested from balb/c mice, encapsulated in CDCA microcapsules, and transplanted into the epididymal tissues of 6 syngeneic diabetic mice, post diabetes confirmation. Pre-transplantation, the microcapsules' morphology, size, CDCA-deep layer distribution, and physical features such as swelling ratio and mechanical strength were analyzed. Post-transplantation, animals' weight, bile acids', and proinflammatory biomarkers' concentrations were analyzed. The control group was diabetic mice that were transplanted encapsulated islets (without PBA).

RESULTS AND CONCLUSION

Islet encapsulation by PBA microcapsules did not compromise the microcapsules' morphology or features. Furthermore, the PBA-graft performed better in terms of glycemic control and resulted in modulation of the bile acid profile in the brain. This is suggestive that the improved glycemic control was mediated via brain-related effects. However, the improvement in graft insulin delivery and glycemic control was short-term.

Pharmacological and Biological Study of Microencapsulated Probucol-Secondary Bile Acid in a Diseased Mouse Model

Probucol (PB) is a highly lipophilic drug with potential protective effects on pancreatic β-cells from inflammation and oxidation. PB has poor bioavailability and solubility, and despite many attempts, significant improvement in antidiabetic effects or absorption has yet to be discovered. Recently, the role of bile acids has been established in significant drug formulation stabilisation effects and as cell-penetrating agents. Promising results in pharmaceutical formulation studies on drug stability and release patterns when lithocholic acid (LCA) is conjugated with PB and sodium alginate (SA) have been demonstrated. Thus, this study aimed to develop and characterise PB microcapsules incorporating LCA and examine the biological effects of the microcapsules in vitro and in vivo. PB/LCA microcapsules were prepared using an encapsulation method, ionic gelation vibrational jet flow technology. LCA incorporation in PB microcapsules showed positive effects on β-cells with improved insulin release, antioxidant activity, and PB intracellular uptake. Diabetic mice gavaged LCA-PB microcapsules showed a significant reduction in diabetes signs and symptoms, better survival rate, reduced blood glucose levels, and pro-inflammatory cytokines, with an increase PB level in blood and tissues suggesting a potential therapy for treating diabetes mellitus.

Enhanced Bilosomal Properties Resulted in Optimum Pharmacological Effects by Increased Acidification Pathways

INTRODUCTION

Recent studies in our laboratory have shown that some bile acids, such as chenodeoxycholic acid (CDCA), can exert cellular protective effects when encapsulated with viable β-cells via anti-inflammatory and anti-oxidative stress mechanisms. However, to explore their full potential, formulating such bile acids (that are intrinsically lipophilic) can be challenging, particularly if larger doses are required for optimal pharmacological effects. One promising approach is the development of nano gels. Accordingly, this study aimed to examine biological effects of various concentrations of CDCA using various solubilising nano gel systems on encapsulated β-cells.

METHODS

Using our established cellular encapsulation system, the Ionic Gelation Vibrational Jet Flow technology, a wide range of CDCA β-cell capsules were produced and examined for morphological, biological, and inflammatory profiles.

RESULTS AND CONCLUSION

Capsules' morphology and topographic characteristics remained similar, regardless of CDCA or nano gel concentrations. The best pharmacological, anti-inflammatory, and cellular respiration, metabolism, and energy production effects were observed at high CDCA and nano gel concentrations, suggesting dose-dependent cellular protective and positive effects of CDCA when incorporated with high loading nano gel.

A Review on Recent Advancement on Age-Related Hearing Loss: The Applications of Nanotechnology, Drug Pharmacology, and Biotechnology

Aging is considered a contributing factor to many diseases such as cardiovascular disease, Alzheimer’s disease, and hearing loss. Age-related hearing loss, also termed presbycusis, is one of the most common sensory impairments worldwide, affecting one in five people over 50 years of age, and this prevalence is growing annually. Associations have emerged between presbycusis and detrimental health outcomes, including social isolation and mental health. It remains largely untreatable apart from hearing aids, and with no globally established prevention strategies in the clinical setting. Hence, this review aims to explore the pathophysiology of presbycusis and potential therapies, based on a recent advancement in bile acid-based bio-nanotechnologies. A comprehensive online search was carried out using the following keywords: presbycusis, drugs, hearing loss, bile acids, nanotechnology, and more than 150 publications were considered directly relevant. Evidence of the multifaceted oxidative stress and chronic inflammation involvement in cellular damage and apoptosis that is associated with a loss of hair cells, damaged and inflamed stria vascularis, and neuronal signalling loss and apoptosis continues to emerge. New robust and effective therapies require drug delivery deeper into the various layers of the cochlea. Bile acid-based nanotechnology has gained wide interest in its permeation-enhancing ability and potential for numerous applications in treating presbycusis.

Pharmacological and Advanced Cell Respiration Effects, Enhanced by Toxic Human-Bile Nano-Pharmaceuticals of Probucol Cell-Targeting Formulations

Bile acids have recently been studied for potential applications as formulation excipients and enhancers for drug release; however, some bile acids are not suitable for this application. Unconjugated lithocholic acid (ULCA) has recently shown drug formulation-stabilizing and anti-inflammatory effects. Lipophilic drugs have poor gut absorption after an oral dose, which necessitates the administration of high doses and causes subsequent side effects. Probucol (PB) is a highly lipophilic drug with poor oral absorption that resulted in restrictions on its clinical prescribing. Hence, this study aimed to design new delivery systems for PB using ULCA-based matrices and to test drug formulation, release, temperature, and biological effects. ULCA-based matrices were formulated for PB oral delivery by applying the jet-flow microencapsulation technique using sodium alginate as a polymer. ULCA addition to new PB matrices improved the microcapsule’s stability, drug release in vitro (formulation study), and showed a promising effect in ex vivo study (p < 0.05), suggesting that ULCA can optimize the oral delivery of PB and support its potential application in diabetes treatment.

Micro-Nano formulation of bile-gut delivery: rheological, stability and cell survival, basal and maximum respiration studies

Probucol (PB) is a drug that exhibits significant hydrophobicity and substantial intra and inter individual variability in oral absorption, with a miniature bioavailability and complex three compartmental pharmacokinetic modelling due to its high lipid affinity, low stability and high octanol to water partition coefficient. Multiple attempts to formulate PB have not produced satisfactory stable matrices, drug-release profile or rheological flow properties for optimum manufacturing conditions, and with positive and none toxic biological effects. Lithocholic acid (LCA) has recently shown to optimise formulation and cell uptake of drugs. Hence, the aim of this study was to design new PB delivery system, using LCA, and examine its morphology, rheology, stability, and cellular effects. PB was formulated with LCA and sodium alginate (PB-LCA-SA) using various microencapsulation methodologies, and best formulation was investigated in vitro and ex vivo. Using our Ionic Gelation Vibrational Jet flow technology, PB-LCA-SA microcapsules showed good stability and significantly enhanced cell viability, cellular respiration, and reduced inflammation suggesting potential LCA applications in PB delivery and biological effects.

Oral gavage of nano-encapsulated conjugated acrylic acid-bile acid formulation in type 1 diabetes altered pharmacological profile of bile acids, and improved glycaemia and suppressed inflammation

BACKGROUND

Ursodeoxycholic acid (UDCA) is a secondary hydrophilic bile acid, metabolised in the gut, by microbiota. UDCA is currently prescribed for primary biliary cirrhosis, and of recently has shown β-cell protective effects, which suggests potential antidiabetic effects. Thus, this study aimed to design targeted-delivery microcapsules for oral uptake of UDCA and test its effects in type 1 diabetes (T1D).

METHODS

UDCA microcapsules were produced using alginate-NM30 matrix. Three equal groups of mice (6-7 mice per group) were gavaged daily UDCA powder, empty microcapsules and UDCA microcapsules for 7 days, then T1D was induced by alloxan injection and treatments continued until mice had to be euthanised due to weight loss > 10% or severe symptoms develop. Plasma, tissues, and faeces were collected and analysed for bile acids' concentrations.

RESULTS

UDCA microcapsules brought about reduction in elevated blood glucose, reduced inflammation and altered concentrations of the primary bile acid chenodeoxycholic acid and the secondary bile acid lithocholic acid, without affecting survival rate of mice.

CONCLUSION

The findings suggest that UDCA exerted direct protective effects on pancreatic β-cells and this is likely to be associated with alterations of concentrations of primary and secondary bile acids in plasma and tissues. Three equal groups of mice were gavaged daily UDCA (ursodeoxycholic acid) powder, empty microcapsules and UDCA microcapsules for 7 days, then T1D was induced and treatments continued until mice had to be euthanised. UDCA microcapsules brought about reduction in elevated blood glucose, reduced inflammation and altered concentrations of the primary bile acid chenodeoxycholic acid and the secondary bile acid lithocholic acid, without affecting survival rate of mice. The findings suggest that UDCA exerted direct protective effects on pancreatic β-cells and this is likely to be associated with alterations of concentrations of primary and secondary bile acids in plasma and tissues.

Bile acid bio-nanoencapsulation improved drug targeted-delivery and pharmacological effects via cellular flux: 6-months diabetes preclinical study

The antilipidemic drug, probucol (PB), has demonstrated potential applications in Type 2 diabetes (T2D) through its protective effects on pancreatic β-cells. PB has poor solubility and bioavailability, and despite attempts to improve its oral delivery, none has shown dramatic improvements in absorption or antidiabetic effects. Preliminary data has shown potential benefits from bile acid co-encapsulation with PB. One bile acid has shown best potential improvement of PB oral delivery (ursodeoxycholic acid, UDCA). This study aimed to examine PB and UDCA microcapsules (with UDCA microcapsules serving as control) in terms of the microcapsules’ morphology, biological effects ex vivo, and their hypoglycemic and antilipidemic and anti-inflammatory effects in vivo. PBUDCA and UDCA microcapsules were examined in vitro (formulation studies), ex vivo and in vivo. PBUDCA microcapsules exerted positive effects on β-cells viability at hyperglycemic state, and brought about hypoglycemic and anti-inflammatory effects on the prediabetic mice. In conclusion, PBUDCA co-encapsulation have showed beneficial therapeutic impact of dual antioxidant-bile acid effects in diabetes treatment.

Bio Micro-Nano Technologies of Antioxidants Optimised Their Pharmacological and Cellular Effects, ex vivo, in Pancreatic β-Cells

Introduction

Recent formulation and microencapsulation studies of probucol (PB) using the polymer sodium alginate (SA) and bile acids have shown promising results but PB stability, and pharmacology profiles remain suboptimal. This study aimed to investigate novel polymers for the nano and micro encapsulation of PB, with the anti-inflammatory bile acid ursodeoxycholic acid (UDCA).

Material and methods

Six formulations using three types of polymers were investigated with and without UDCA. The polymers were NM30D, RL30D, and RS30D and they were mixed with SA and PB at set ratios and microencapsulated using oscillating-voltage-mediated nozzle technology coupled with ionic gelation. The microcapsules were examined for physical and biological effects using pancreatic β-cells.

Results and discussion

UDCA addition did not adversely affect the morphology and physical features of the microcapsules. Despite thermal stability remaining unchanged, bile acid incorporation did enhance the electrokinetic stability of the formulation system for NM30D and RL30D polymers. Mechanical stability remained similar in all groups. Enhanced uptake of PB from the microcapsule by pancreatic β-cells was only seen with NM30D-UDCA-intercalated microcapsules and this effect was sustained at both glucose levels of 5.5 and 35.5 mM.

Conclusion

UDCA addition enhanced PB delivery and biological effects in a formulation-dependent manner.

A second-generation micro/nano capsules of an endogenous primary un-metabolised bile acid, stabilized by Eudragit-alginate complex with antioxidant compounds

Bile acids (BAs) are amphiphilic compounds and of recently have demonstrated wide range of formulation stabilizing effects. A recent study showed that primary un-metabolised bile acids (PUBAs) have β-cell protective effects, and synergistic antidiabetic effects when combined with antioxidant and anti-inflammatory drugs, such as probucol (PB). Thus, this study aimed to design and test microcapsules containing a PUBA incorporated with PB and an alginate-Eudragit matrix.

Six types of microcapsules were developed without (control) or with (test) PUBA, and tested for internal and external features and β-cell protective effects.

The incorporation of PB-alginate-Eudragit with PUBA produced stable microcapsules but did not exert consistent positive effects on cell viability in the hyperglycaemic state, which suggests that PUBA in alginate-Eudragit matrices did not exhibit synergistic effects with PB nor exerted antidiabetic effects.

An in vivo pharmacological study: Variation in tissue-accumulation for the drug probucol as the result of targeted microtechnology and matrix-acrylic acid optimization and stabilization techniques

Type 2 diabetes (T2D) is characterised by β-cell damage and hyperglycaemia. The lipophilic drug, probucol, has shown significant β-cell protective and potential antidiabetic effects, which were enhanced by hydrophilic bile acid incorporation using taurocholic acid and chenodeoxycholic acid. However, probucol has severe cardiotoxicity and a variable absorption profile, which limit its potential applications in T2D. Accordingly, this study aimed to design multiple formulations to optimise probucol oral delivery in T2D and test their effects on probucol absorption and accumulation in the heart. Adult male mice were given a high fat diet (HFD), and a week later, injected with a single dose of alloxan to accelerate T2D development, and once diabetes confirmed, divided into three groups (six to seven mice each). The groups were gavaged a daily dose of probucol powder, probucol microcapsules, or probucol-bile acid microcapsules for three months, and euthanized; and blood, tissues, and feces collected for blood glucose and probucol concentration analyses. Probucol concentrations in plasma were similar among all the groups. Groups given probucol microcapsules and probucol-bile acid microcapsules showed significant reduction in probucol accumulation in the heart compared with the group given probucol powder (p<0.05). Probucol microencapsulation with or without bile acids reduced its accumulation in heart tissues, without changing plasma concentrations, which may be beneficial in reducing its cardiotoxicity and optimise its potential applications in T2D.

Bile Acids and Their Derivatives as Potential Modifiers of Drug Release and Pharmacokinetic Profiles

Bile acids have received considerable interest in the drug delivery research due to their peculiar physicochemical properties and biocompatibility. The main advantage of bile acids as drug absorption enhancers is their ability to act as both drug solubilizing and permeation-modifying agents. Therefore, bile acids may improve bioavailability of drugs whose absorption-limiting factors include either poor aqueous solubility or low membrane permeability. Besides, bile acids may withstand the gastrointestinal impediments and aid in the transporter-mediated absorption of physically complexed or chemically conjugated drug molecules. These biomolecules may increase the drug bioavailability also at submicellar levels by increasing the solubility and dissolution rate of non-polar drugs or through the partition into the membrane and increase of membrane fluidity and permeability. Most bile acid-induced effects are mediated by the nuclear receptors that activate transcriptional networks, which then affect the expression of a number of target genes, including those for membrane transport proteins, affecting the bioavailability of a number of drugs. Besides micellar solubilization, there are many other types of interactions between bile acids and drug molecules, which can influence the drug transport across the biological membranes. Most common drug-bile salt interaction is ion-pairing and the formed complexes may have either higher or lower polarity compared to the drug molecule itself. Furthermore, the hydroxyl and carboxyl groups of bile acids can be utilized for the covalent conjugation of drugs, which changes their physicochemical and pharmacokinetic properties. Bile acids can be utilized in the formulation of conventional dosage forms, but also of novel micellar, vesicular and polymer-based therapeutic systems. The availability of bile acids, along with their simple derivatization procedures, turn them into attractive building blocks for the design of novel pharmaceutical formulations and systems for the delivery of drugs, biomolecules and vaccines. Although toxic properties of hydrophobic bile acids have been described, their side effects are mostly produced when present in supraphysiological concentrations. Besides, minor structural modifications of natural bile acids may lead to the creation of bile acid derivatives with the reduced toxicity and preserved absorption-enhancing activity.

Bile Acids and Their Derivatives as Potential Modifiers of Drug Release and Pharmacokinetic Profiles

Bile acids have received considerable interest in the drug delivery research due to their peculiar physicochemical properties and biocompatibility. The main advantage of bile acids as drug absorption enhancers is their ability to act as both drug solubilizing and permeation-modifying agents. Therefore, bile acids may improve bioavailability of drugs whose absorption-limiting factors include either poor aqueous solubility or low membrane permeability. Besides, bile acids may withstand the gastrointestinal impediments and aid in the transporter-mediated absorption of physically complexed or chemically conjugated drug molecules. These biomolecules may increase the drug bioavailability also at submicellar levels by increasing the solubility and dissolution rate of non-polar drugs or through the partition into the membrane and increase of membrane fluidity and permeability. Most bile acid-induced effects are mediated by the nuclear receptors that activate transcriptional networks, which then affect the expression of a number of target genes, including those for membrane transport proteins, affecting the bioavailability of a number of drugs. Besides micellar solubilization, there are many other types of interactions between bile acids and drug molecules, which can influence the drug transport across the biological membranes. Most common drug-bile salt interaction is ion-pairing and the formed complexes may have either higher or lower polarity compared to the drug molecule itself. Furthermore, the hydroxyl and carboxyl groups of bile acids can be utilized for the covalent conjugation of drugs, which changes their physicochemical and pharmacokinetic properties. Bile acids can be utilized in the formulation of conventional dosage forms, but also of novel micellar, vesicular and polymer-based therapeutic systems. The availability of bile acids, along with their simple derivatization procedures, turn them into attractive building blocks for the design of novel pharmaceutical formulations and systems for the delivery of drugs, biomolecules and vaccines. Although toxic properties of hydrophobic bile acids have been described, their side effects are mostly produced when present in supraphysiological concentrations. Besides, minor structural modifications of natural bile acids may lead to the creation of bile acid derivatives with the reduced toxicity and preserved absorption-enhancing activity.

The biological effects of the hypolipidaemic drug probucol microcapsules fed daily for 4 weeks, to an insulin-resistant mouse model: potential hypoglycaemic and anti-inflammatory effects

Probucol (PB) is an hypolipidaemic drug with potential antidiabetic effects. We showed recently using in vitro studies that when PB was incorporated with stabilising lipophilic bile acids and microencapsulated using the polymer sodium alginate, the microcapsules showed good stability but poor and irregular PB release. This suggests that PB microcapsules may exhibit better release profile and hence better absorption, if more hydrophilic bile acids were used, such as ursodeoxycholic acid (UDCA). Accordingly, this study aimed to produce PB-UDCA microcapsules and examine PB absorption and antidiabetic effects in our mouse-model of insulin-resistance and diabetes (fed high-fat diet; HFD). The study also aimed to examine the effects of the microcapsules on the bile acid profile. Healthy mice (fed low-fat diet; LFD) were used as control. Seventy mice were randomly allocated into seven equal groups: LFD, HFD given empty microcapsules, HFD given metformin (M), HFD given standard-dose probucol (PB-SD), HFD given high-dose probucol (PB-H), HFD given UDCA microcapsules and HFD given PB-UDCA microcapsules. Blood glucose (BG), inflammatory biomarkers (TNF-α, IFN-γ, IL-1β, IL-6, IL-10, IL-12 and IL-17), plasma cholesterol, non-esterified fatty acids and triglycerides were analysed together with plasma bile acid and probucol concentrations. PB-UDCA microcapsules reduced BG in HFD mice, but did not reduce inflammation or improve lipid profile, compared with positive control (HFD) group. Although PB-UDCA microcapsules did not exert hypolipidaemic or antiinflammatory effects, they resulted in significant hypoglycaemic effects in a mouse model of insulin resistance, which suggests potential applications in insulin-resistance and glucose haemostasis.

The incorporation of water-soluble gel matrix into bile acid-based microcapsules for the delivery of viable β-cells of the pancreas, in diabetes treatment: biocompatibility and functionality studies

In recent studies, we microencapsulated pancreatic β-cells using sodium alginate (SA) and poly-L-ornithine (PLO) and the bile acid, ursodeoxycholic acid (UDCA), and tested the morphology and cell viability post-microencapsulation. Cell viability was low probably due to limited strength of the microcapsules. This study aimed to assess a β-cell delivery system which consists of UDCA-based microcapsules incorporated with water-soluble gel matrix. The polyelectrolytes, water-soluble gel (WSG), polystyrenic sulphate (PSS), PLO and polyallylamine (PAA) at ratios 4:1:1:2.5 with or without 4% UDCA, were incorporated into our microcapsules, and cell viability, metabolic profile, cell functionality, insulin production, levels of inflammation, microcapsule morphology, cellular distribution, UDCA partitioning, biocompatibility, thermal and chemical stabilities and the microencapsulation efficiency were examined. The incorporation of UDCA with PSS, PAA and WSG enhanced cell viability per microcapsule (p < 0.05), cellular metabolic profile (p < 0.01) and insulin production (p < 0.01); reduced the inflammatory release TNF-α (p < 0.01), INF-gamma (p < 0.01) and interleukin-6 (IL-6) (p < 0.01); and ceased the production of IL-1β. UDCA, PSS, PAA and WSG addition did not change the microencapsulation efficiency and resulted in biocompatible microcapsules. Our designed microcapsules showed good morphology and desirable insulin production, cell functionality and reduced inflammatory profile suggesting potential applications in diabetes.

The effect of a tertiary bile acid, taurocholic acid, on the morphology and physical characteristics of microencapsulated probucol: potential applications in diabetes: a characterization study

In recent studies, we designed multi-compartmental microcapsules as a platform for the targeted oral delivery of lipophilic drugs in an animal model of type 2 diabetes (T2D). Probucol (PB) is a highly lipophilic, antihyperlipidemic drug with potential antidiabetic effects. PB has low bioavailability and high inter-individual variations in absorption, which limits its clinical applications. In a new study, the bile acid, taurocholic acid (TCA), exerted permeation enhancing effects in vivo. Accordingly, this study aimed to design and characterize TCA-based PB microcapsules and examine the effects of TCA on the microcapsules' morphology, stability, and release profiles. Microcapsules were prepared using the polymer sodium alginate (SA). Two types of microcapsules were produced, one without TCA (PB-SA, control) and one with TCA (PB-TCA-SA, test). Microcapsules were studied in terms of morphology, surface structure and composition, size, drug contents, cross-sectional imaging (using microtomography (Micro-CT) analysis), Zeta potential, thermal and chemical profiles, rheological parameters, swelling, mechanical strength, and release studies at various temperature and pH values. The production yield and the encapsulation efficiency were also studied together with in vitro efficacy testing of cell viability at various glucose concentrations and insulin and TNF-α production using clonal-mouse pancreatic β-cells. PB-TCA-SA microcapsules showed uniform structure and even distribution of TCA within the microcapsules. Drug contents, Zeta potential, size, rheological parameters, production yield, and the microencapsulation efficiency remained similar after TCA addition. In vitro testing showed PB-TCA-SA microcapsules improved β-cell survival under hyperglycemic states and reduced the pro-inflammatory cytokine TNF-α while increasing insulin secretions compared with PB-SA microcapsules. PB-TCA-SA microcapsules also showed good stability, better mechanical (p < 0.01) and swelling (p < 0.01) characteristics, and optimized controlled release at pH 7.8 (p < 0.01) compared with control, suggesting desirable targeted release properties and potential applications in the oral delivery of PB in T2D.