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

Tailoring of chitosan/diacrylated pluronic system as a versatile nanoplatform for the amelioration of radiation-induced cognitive dysfunction

Rutin (RUT) is a biologically active flavonoid that is reported to modulate radiation-induced brain dysfunctions. However, RUT's poor water solubility and low brain bioavailability limit its clinical use. To increase its brain bioavailability, RUT was loaded onto nanoplatforms based on chitosan/diacrylated pluronic (CS/DA-PLUR) nanogels synthesized by gamma radiation. The optimized formulation was investigated as a carrier system for RUT. Based on pilot experiments' results, the cranial radiation (CR) dose that induced cognitive dysfunction was selected. In the main experiment, rats were pre-treated orally with either free RUT or RUT-CS/DA-PLUR. Rats' cognitive and motor functions were assessed; 24 h later, rats were sacrificed, and the whole brain was separated for histopathological examination and biochemical estimation of brain content of acetylcholine esterase (AChE), neurotransmitters, oxidative stress markers, and interleukin-1β. CR produced prominent impairment in spatial and non-spatial learning memory, motor coordination, and muscular strength. Moreover, histopathological and biochemical alterations in brain contents of neurotransmitters, oxidative stress, and interleukin-1β were induced by CR. Conversely, RUT-CS/DA-PLUR, but not free RUT, successfully guarded against all the detrimental effects induced by CR. Based on the current findings, loading of RUT enhanced its bioavailability and therapeutic effectiveness by restoring the cognitive functions impaired by CR.

Intranasal Zolmitriptan-Loaded Bilosomes with Extended Nasal Mucociliary Transit Time for Direct Nose to Brain Delivery

This study aimed at delivering intranasal zolmitriptan directly to the brain through preparation of bilosomes incorporated into a mucoadhesive in situ gel with extended nasal mucociliary transit time. Zolmitriptan-loaded bilosomes were constructed through a thin film hydration method applying Box-Behnken design. The independent variables were amount of sodium deoxycholate and the amount and molar ratio of cholesterol/Span® 40 mixture. Bilosomes were assessed for their entrapment efficiency, particle size and in vitro release. The optimal bilosomes were loaded into mucoadhesive in situ gel consisting of poloxamer 407 and hydroxypropyl methylcellulose. The systemic and brain kinetics of Zolmitriptan were evaluated in rats by comparing intranasal administration of prepared gel to an IV solution. Statistical analysis suggested an optimized bilosomal formulation composition of sodium deoxycholate (5 mg) with an amount and molar ratio of cholesterol/Span® 40 mixture of 255 mg and 1:7.7, respectively. The mucoadhesive in situ gel containing bilosomal formulation had a sol-gel temperature of 34.03 °C and an extended mucociliary transit time of 22.36 min. The gelling system possessed enhanced brain bioavailability compared to bilosomal dispersion (1176.98 vs. 835.77%, respectively) following intranasal administration. The gel revealed successful brain targeting with improved drug targeting efficiency and direct transport percentage indices. The intranasal delivery of mucoadhesive in situ gel containing zolmitriptan-loaded bilosomes offered direct nose-to-brain drug targeting with enhanced brain bioavailability.

Measuring the oral bioavailability of protein hydrolysates derived from food sources: A critical review of current bioassays

BACKGROUND

Food proteins are a source of hydrolysates with potentially useful biological attributes. Bioactive peptides from food-derived proteins are released from hydrolysates using exogenous industrial processes or endogenous intestinal enzymes. Current in vitro permeability assays have limitations in predicting the oral bioavailability (BA) of bioactive peptides in humans. There are also difficulties in relating the low blood levels of food-derived bioactive peptides detected in preclinical in vivo models to pharmacodynamic read-outs relevant for humans.

SCOPE AND APPROACH

In this review, we describe in vitro assays of digestion, permeation, and metabolism as indirect predictors of the potential oral BA of hydrolysates and their constituent bioactive peptides. We discuss the relationship between industrial hydrolysis processes and the oral BA of hydrolysates and their peptide by-products.

KEY FINDINGS

Hydrolysates are challenging for analytical detection methods due to capacity for enzymatic generation of peptides with novel sequences and also new modifications of these peptides during digestion. Mass spectrometry and peptidomics can improve the capacity to detect individual peptides released from complex hydrolysates in biological milieu.

Bile acid transporter-mediated oral absorption of insulin via hydrophobic ion-pairing approach

Despite many ongoing and innovative approaches, there are still formidable challenges in the clinical translation of oral peptide drugs into marketable products due to their low absorption and poor bioavailability. Herein, a novel nanocarrier platform was developed that employs a hydrophobic ion-pairing (HIP) of model peptide (insulin) and the anionic bile salt (sodium glycodeoxycholate, SGDC), and markedly improves intestinal absorption via the bile acid pathway. The developed HIP-nanocomplexes (C1 and C2) were optimized, characterized, and in vitro and in vivo evaluation were performed to assess oral efficacy of these system. The optimal molar ratios of C1 and C2-nanocomplexes were 30:1 and 6:1 (SGDC:insulin), respectively. Compared to the insulin solution, the C1 and C2 nanocomplexes significantly enhanced the permeation of insulin across the Caco-2 cell monolayers, with 6.36- and 4.05-fold increases in apparent permeability, respectively. Uptake mechanism studies were conducted using different endocytosis inhibitors and apical sodium-dependent bile acid transporter (ASBT)-transfected MDCK cells, which demonstrated the involvement of the energy-dependent ASBT-mediated active transport. Furthermore, the intrajejunal administration of C1 and C2 resulted in their pharmacological availabilities (PA) being 6.44% and 0.10%, respectively, indicating increased potential for C1, when compared to C2. Similarly, the PA and the relative bioavailability with intrajejunal administration of the C1 were 17.89-fold and 16.82-fold greater than those with intracolonic administration, respectively, confirming better jejunal absorption of C1. Overall, these findings indicate that the HIP-nanocomplexes could be a prominent platform for the effective delivery of peptides with improved intestinal absorption.

Nonimmunogenic Hydrogel-Mediated Delivery of Antibiotics Outperforms Clinically Used Formulations in Mitigating Wound Infections

Treatment of chronic wound infections caused by Gram-positive bacteria such as Staphylococcus aureus is highly challenging due to the low efficacy of existing formulations, thereby leading to drug resistance. Herein, we present the synthesis of a nonimmunogenic cholic acid-glycine-glycine conjugate (A6) that self-assembles into a supramolecular viscoelastic hydrogel (A6 gel) suitable for topical applications. The A6 hydrogel can entrap different antibiotics with high efficacy without compromising its viscoelastic behavior. Activities against different bacterial species using a disc diffusion assay demonstrated the antimicrobial effect of the ciprofloxacin-loaded A6 hydrogel (CPF-Gel). Immune profiling and gene expression studies after the application of the A6 gel to mice confirmed its nonimmunogenic nature to host tissues. We further demonstrated that topical application of CPF-Gel clears S. aureus-mediated wound infections more effectively than clinically used formulations. Therefore, cholic acid-derived hydrogels are an efficacious matrix for topical delivery of antibiotics and should be explored further.

Bile Salts in Chiral Micellar Electrokinetic Chromatography: 2000-2020

Bile salts are naturally occurring chiral surfactants that are able to solubilize hydrophobic compounds. Because of this ability, bile salts were exploited as chiral selectors added to the background solution (BGS) in the chiral micellar electrokinetic chromatography (MEKC) of various small molecules. In this review, we aimed to examine the developments in research on chiral MEKC using bile salts as chiral selectors over the past 20 years. The review begins with a discussion of the aggregation of bile salts in chiral recognition and separation, followed by the use of single bile salts and bile salts with other chiral selectors (i.e., cyclodextrins, proteins and single-stranded DNA aptamers). Advanced techniques such as partial-filling MEKC, stacking and single-drop microextraction were considered. Potential applications to real samples, including enantiomeric impurity analysis, were also discussed.

Suppressive effect of goat bile in Plasmodium berghei ANKA infection in mice

BACKGROUND AND AIM

Some individuals in Indonesia consume intact goat gallbladder to prevent and treat malaria. The acute and subacute toxicity tests of goat bile (GB) have shown mild diarrhea in mice. Therefore, this study aimed to evaluate the suppressive effect of GB on parasitemia, splenomegaly, hepatomegaly, and blood biochemistry to assess liver and kidney function in BALB/c mice infected with Plasmodium berghei ANKA.

MATERIALS AND METHODS

Fifty healthy mice were infected with P. berghei ANKA and divided into five groups. Mice in three groups were administered 0.5 mL of 25%, 50%, or 100% of GB by gavage. Animals in Group 4 were administered 187.2 mg/kg BW of dihydroartemisinin-piperaquine phosphate as a positive control (POS Group). Mice in fifth group were administered sterile water as negative (NEG) controls. Further, 30 uninfected mice were divided into groups 6-8 and administered GB as were mice in the first three groups. Group 9 included 10 uninfected and untreated animals as healthy controls. Treatments were administered in a 4-day suppressive test followed by daily observation of Giemsa-stained blood smears. On day 7, mice were sacrificed to measure the length and weight of spleens and livers, plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN), and creatinine.

RESULTS

GB suppressed parasitemia but did not affect the size and weight of spleens or livers or plasma levels of AST and ALT compared to uninfected GB-treated and healthy control animals. Conversely, plasma levels of BUN and creatinine were suppressed and remained in the normal range in all groups of mice.

CONCLUSION

GB suppresses parasitemia with no significant impact on hepatic enzymes in GB-treated infected mice. Liver dysfunction in GB-treated infected mice was due to P. berghei rather than GB treatment.

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.

Evaluation for Potential Drug-Drug Interaction of MT921 Using In Vitro Studies and Physiologically-Based Pharmacokinetic Models

MT921 is a new injectable drug developed by Medytox Inc. to reduce submental fat. Cholic acid is the active pharmaceutical ingredient, a primary bile acid biosynthesized from cholesterol, endogenously produced by liver in humans and other mammals. Although individuals treated with MT921 could be administered with multiple medications, such as those for hypertension, diabetes, and hyperlipidemia, the pharmacokinetic drug–drug interaction (DDI) has not been investigated yet. Therefore, we studied in vitro against drug-metabolizing enzymes and transporters. Moreover, we predicted the potential DDI between MT921 and drugs for chronic diseases using physiologically-based pharmacokinetic (PBPK) modeling and simulation. The magnitude of DDI was found to be negligible in in vitro inhibition and induction of cytochrome P450s and UDP-glucuronosyltransferases. Organic anion transporting polypeptide (OATP)1B3, organic anion transporter (OAT)3, Na⁺-taurocholate cotransporting polypeptide (NTCP), and apical sodium-dependent bile acid transporter (ASBT) are mainly involved in MT921 transport. Based on the result of in vitro experiments, the PBPK model of MT921 was developed and evaluated by clinical data. Furthermore, the PBPK model of amlodipine was developed and evaluated. PBPK DDI simulation results indicated that the pharmacokinetics of MT921 was not affected by the perpetrator drugs. In conclusion, MT921 could be administered without a DDI risk based on in vitro study and related in silico simulation. Further clinical studies are needed to validate this finding.

Facilitated Buccal Insulin Delivery via Hydrophobic Ion-Pairing Approach: In vitro and ex vivo Evaluation

BACKGROUND

The clinical use of therapeutic peptides has been limited because of their inefficient delivery approaches and, therefore, inadequate delivery to target sites. Buccal administration of therapeutic peptides offers patients a potential alternative to the current invasive routes of administration.

PURPOSE

The aim of the study was to fabricate hydrophobic ion-pairing (HIP)-nanocomplexes (C1 and C2) utilizing anionic bile salts and cationic peptides, and to assess their permeability across TR146 buccal cell layers and porcine buccal tissue.

METHODS

C1 and C2-nanocomplexes were fabricated using the HIP approach. In addition, their physiochemical and morphological attributes, in vitro and ex vivo permeability properties, and qualitative and quantitative cellular uptake were evaluated and compared. The localization of C1 and C2-nanocomplexes in porcine buccal tissue was determined using confocal laser scanning microscopy.

RESULTS

The C1-nanocomplex was the superior nanocarrier and significantly enhanced the transport of insulin across TR146 cell layers and porcine buccal tissue, exhibiting a 3.00- and 51.76-fold increase in permeability coefficient, respectively, when compared with insulin solution (p < 0.01). C1-nanocomplex was more efficient than C2-nanocomplex at facilitating insulin permeability, with a 2.18- and 27.64-fold increase across TR146 cell layers and porcine buccal tissue, respectively. The C1-nanocomplex demonstrated immense uptake and localization of insulin in TR146 cells and porcine buccal tissue, as evidenced by a highly intense fluorescence in TR146 cells, and a great shift of fluorescence intensity towards the inner region of buccal tissue over time. The increase in fluorescence intensity was observed in the order of C1 > C2 > insulin solution.

CONCLUSION

In this study, we highlighted the efficacy of potential nanocarriers in addressing the daunting issues associated with the invasive administration of insulin and indicated a promising strategy for the buccal administration and delivery of this life-saving peptide hormone.

Entrapment of Hydrophilic and Hydrophobic Molecules in Beads Prepared from Isolated Denatured Whey Protein

The oral route of administration is by far the most convenient route, especially in the treatment of chronic conditions. However, many therapeutics present formulation difficulties which make them unsuitable for oral delivery. Recently, we synthesized a denatured whey protein isolate (dWPI) bead entrapped with insulin. Our present goal was to assess the suitability of this delivery system to the delivery of other potential molecules, both hydrophilic and hydrophobic. Beads of 1.2–1.5 mm in diameter were entrapped with four payloads representing a range of solubilities. The water-soluble payloads were sodium fluorescein (SF) and FITC dextran 4000 Da (FD4), while the hydrophobic ones were Fast Green and curcumin. Encapsulation efficiency (EE) was 73%, 84%, 70%, and 83% for SF, FD4, Fast Green, and curcumin-loaded beads, respectively. The corresponding loading capacity for each bead was 0.07%, 1.1%, 0.75%, and 1.1%, respectively. Each payload produced different release profiles in simulated gastric fluid (SGF) and simulated intestinal fluids (SIF). SF released steadily in both SGF and SIF. FD4 and curcumin release was not substantial in any buffers, while Fast Green release was low in SGF and high in SIF. The differences in release behaviour were likely due to the varying properties of the payloads. The effect of proteolysis on beads suggested that enzymatic degradation of the whey bead may promote payload release. The beads swelled rapidly in SGF compared to SIF, which likely contributed to the release from the beads, which was largely governed by solvent diffusion and polymer relaxation. Our results offer a systematic examination of the behaviour of hydrophilic and hydrophobic payloads in a dWPI delivery system. These beads may be further designed to orally deliver poorly permeable macromolecules and poorly soluble small molecules of pharmaceutical interest.

The influence of the gut microbiota on the bioavailability of oral drugs

Due to its safety, convenience, low cost and good compliance, oral administration attracts lots of attention. However, the efficacy of many oral drugs is limited to their unsatisfactory bioavailability in the gastrointestinal tract. One of the critical and most overlooked factors is the symbiotic gut microbiota that can modulate the bioavailability of oral drugs by participating in the biotransformation of oral drugs, influencing the drug transport process and altering some gastrointestinal properties. In this review, we summarized the existing research investigating the possible relationship between the gut microbiota and the bioavailability of oral drugs, which may provide great ideas and useful instructions for the design of novel drug delivery systems or the achievement of personalized medicine.

Challenges in Oral Drug Delivery and Applications of Lipid Nanoparticles as Potent Oral Drug Carriers for Managing Cardiovascular Risk Factors

BACKGROUND

The oral application of drugs is the most popular route through which the systemic effect can be achieved. Nevertheless, oral administration is limited by difficulties related to the physicochemical properties of the drug molecule, including low aqueous solubility, instability, low permeability, and rapid metabolism, all of which result in low and irregular oral bioavailability.

OBJECTIVE

The enhancement of oral bioavailability of drug molecules with such properties could lead to extreme complications in drug preparations. Oral lipid-based nanoparticles seem to possess extensive advantages due to their ability to increase the solubility, simplifying intestinal absorption and decrease or eradicate the effect of food on the absorption of low soluble, lipophilic drugs and therefore improving the oral bioavailability.

METHODS

The present review provides a summary of the general theory of lipid-based nanoparticles, their preparation methods, as well as their oral applications. Moreover, oral drug delivery challenges are discussed.

RESULTS

According to this review, the most frequent types of lipid-based nanoparticle, the solid lipid nanoparticles and nanostructured lipid carriers are potent oral carriers due to their ability to penetrate the oral drug adsorption barriers. Moreover, such lipid nanoparticles can be beneficial drug carriers against cardiovascular risk disorders as diabetes, hypertension, etc. Conclusion: In this review, the most current and promising studies involving Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as oral drug carriers are reported aiming to assist researchers who focus their research on lipid-based nanoparticles.

Sodium alginate microencapsulation improves the short-term oral bioavailability of cannabidiol when administered with deoxycholic acid

BACKGROUND

Cannabidiol (CBD) confers therapeutic effects in some neurological disorders via modulation of inflammatory, oxidative and cell-signalling pathways. However, CBD is lipophilic and highly photooxidative with low oral bioavailability in plasma and brain. In this study, we aimed to design and test a CBD microencapsulation method as a drug delivery strategy to improve the absorption of CBD. Additionally, we evaluated the brain uptake of CBD capsules when administered alongside capsules containing a permeation-modifying bile acid, deoxycholic acid (DCA).

METHODS

Microcapsules containing either CBD or DCA were formed using the ionic gelation method with 1.5% sodium alginate formulations and 100 mM calcium chloride. C57BL/6J wild type mice randomly assigned to three treatment groups (3-4 mice per group) were administered CBD in the following preparations: 1) CBD capsules, 2) CBD capsules + DCA capsules and 3) naked CBD oil (control). To assess the short-term bioavailability of CBD, plasma and brain samples were collected at 0.3, 1 and 3 hours post administration and CBD levels were analysed with liquid chromatography mass spectrometer.

RESULTS

We produced spherical capsules at 400 ± 50 μm in size. The CBD capsules were calculated to have a drug loading of 2% and an encapsulation efficiency of 23%. Mice that received CBD capsules + DCA capsules showed a 40% and 47% increase in CBD plasma concentration compared to mice on CBD capsules and naked CBD oil, respectively. Furthermore, the CBD capsules + DCA capsules group showed a 48% and 25% increase in CBD brain concentration compared to mice on CBD capsules and naked CBD oil, respectively. In mice treated with CBD capsules + DCA capsules, the brain CBD concentration peaked at 0.3 hours with a 300% increased availability compared to CBD capsules and naked CBD oil groups, which peaked at 1 hour after administration.

CONCLUSIONS

The microencapsulation method combined with a permeation enhancer, DCA increased the short-term bioavailability of CBD in plasma and brain.

Development of an Age-Appropriate Mini Orally Disintegrating Carvedilol Tablet with Paediatric Biopharmaceutical Considerations

Owing to considerable differences observed in anatomy and physiology between paediatric subsets, it has been well established that children respond to drugs differently compared to adults. Furthermore, from a formulation perspective, there is a distinct challenge to develop a dosage form that is capable of safely, accurately, and reliably delivering the dose across the whole paediatric population. Orally disintegrating mini-tablets (ODMT) have widely been considered as an age-appropriate formulation option that possess the ability for adequate dose flexibility, avoids swallowing difficulties, and exhibits superior stability due to its solid state. Within this study, two strengths (0.5 mg and 2 mg) of carvedilol ODMT formulations were developed using an excipient composition and load that is appropriate for paediatric use. The formulations demonstrated adequate mechanical strength (>20 N) and fast disintegration times (<30 s). Dissolution profiles observed were robust and comparable to the marketed conventional tablet formulation across various parts of the gastrointestinal (GI) tract in both the fed and fasted state, signifying appropriate efficacy, quality, and performance. As such, the formulations developed in this study show potential to address the need of an 'age-appropriate' formulation of carvedilol, as highlighted by the European Medicines Agency (EMA) Inventory of the Needs for Paediatric Medicine.

Computationally guided high-throughput design of self-assembling drug nanoparticles

Nanoformulations of therapeutic drugs are transforming our ability to effectively deliver and treat a myriad of conditions. Often, however, they are complex to produce and exhibit low drug loading, except for nanoparticles formed via co-assembly of drugs and small molecular dyes, which display drug-loading capacities of up to 95%. There is currently no understanding of which of the millions of small-molecule combinations can result in the formation of these nanoparticles. Here we report the integration of machine learning with high-throughput experimentation to enable the rapid and large-scale identification of such nanoformulations. We identified 100 self-assembling drug nanoparticles from 2.1 million pairings, each including one of 788 candidate drugs and one of 2,686 approved excipients. We further characterized two nanoparticles, sorafenib-glycyrrhizin and terbinafine-taurocholic acid both ex vivo and in vivo. We anticipate that our platform can accelerate the development of safer and more efficacious nanoformulations with high drug-loading capacities for a wide range of therapeutics.

Dyslipidemia Management in 2020: An Update on Diagnosis and Therapeutic Perspectives

Cardiovascular diseases are the leading cause of death in the modern world and dyslipidemia is one of the major risk factors. The current therapeutic strategies for cardiovascular diseases involve the management of risk factors, especially dyslipidemia and hypertension. Recently, the updated guidelines of dyslipidemia management were presented, and the newest data were included in terms of diagnosis, imaging, and treatment. In this targeted literature review, the researchers presented the most recent evidence on dyslipidemia management by including the current therapeutic goals for it. In addition, the novel diagnostic tools based on theranostics are shown. Finally, the future perspectives on treatment based on novel drug delivery systems and their potential to be used in clinical trials were also analyzed. It should be noted that dyslipidemia management can be achieved by the strict lifestyle change, i.e., by adopting a healthy life, and choosing the most suitable medication. This review can help medical professionals as well as specialists of other sciences to update their knowledge on dyslipidemia management, which can lead to better therapeutic outcomes and newer drug developments.

Bile acids as novel enhancers of CNS targeting antitumor drugs: a comprehensive review

Despite a relatively low prevalence of primary brain tumors, they continuously attract scientific interest because of the complexity of their treatment due to their location behind the blood-brain barrier. The main challenge in treatment of brain tumors is not the efficacy of the drugs, per se, but the low efficiency of drug delivery to malignant cells. At the core of the problem is the complex structure of the blood-brain barrier. Nowadays, there is evidence supporting the claim that bile acids have the ability to cross the blood-brain barrier. That ability can be exploited by taking a part in novel drug carrier designs. Bile acids represent a drug carrier system as a part of a mixed micelle composition, bilosomes and conjugates with various drugs. This review discusses the current knowledge related to bile acid molecules as drug penetration modifying agents, with the focus on central nervous system antitumor drug delivery.

Loss of Claudin-3 Impairs Hepatic Metabolism, Biliary Barrier Function, and Cell Proliferation in the Murine Liver

BACKGROUND & AIMS

Tight junctions in the liver are essential to maintain the blood-biliary barrier, however, the functional contribution of individual tight junction proteins to barrier and metabolic homeostasis remains largely unexplored. Here, we describe the cell type-specific expression of tight junction genes in the murine liver, and explore the regulation and functional importance of the transmembrane protein claudin-3 in liver metabolism, barrier function, and cell proliferation.

METHODS

The cell type-specific expression of hepatic tight junction genes is described using our mouse liver single-cell sequencing data set. Differential gene expression in Cldn3-/- and Cldn3+/+ livers was assessed in young and aged mice by RNA sequencing (RNA-seq), and hepatic tissue was analyzed for lipid content and bile acid composition. A surgical model of partial hepatectomy was used to induce liver cell proliferation.

RESULTS

Claudin-3 is a highly expressed tight junction protein found in the liver and is expressed predominantly in hepatocytes and cholangiocytes. The histology of Cldn3-/- livers showed no overt phenotype, and the canalicular tight junctions appeared intact. Nevertheless, by RNA-seq we detected a down-regulation of metabolic pathways in the livers of Cldn3-/- young and aged mice, as well as a decrease in lipid content and a weakened biliary barrier for primary bile acids, such as taurocholic acid, taurochenodeoxycholic acid, and taurine-conjugated muricholic acid. Coinciding with defects in the biliary barrier and lower lipid metabolism, there was a diminished hepatocyte proliferative response in Cldn3-/- mice after partial hepatectomy.

CONCLUSIONS

Our data show that, in the liver, claudin-3 is necessary to maintain metabolic homeostasis, retention of bile acids, and optimal hepatocyte proliferation during liver regeneration. The RNA-seq data set can be accessed at: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE159914.

Sodium glycodeoxycholate and sodium deoxycholate as epithelial permeation enhancers: in vitro and ex vivo intestinal and buccal bioassays

Bile salts were first tested as epithelial permeation enhancers (PEs) for the intestine and buccal routes over 20 years ago. They are not as popular as other PEs due to their non-specific mechanism of action and perceived toxicity potential. We revisited two of them by comparing efficacy and toxicity of sodium glycodeoxycholate (SGC) and sodium deoxycholate (DC) for both routes using in vitro and ex vivo methods. Cytotoxicity assays in Caco-2 cells revealed that both agents altered cellular parameters at concentrations >2 mM over 60 min. Both agents reduced the transepithelial resistance (TEER) and doubled the Papp of [3H]-octreotide across isolated rat colonic mucosae mounted in Ussing chambers at 10 mM concentrations. In some studies, 10 mM GDC also increased the Papp of the paracellular marker, FITC-dextran 4000 (FD4) and the fluorescent peptide, FITC-LKP, across colonic mucosae. Tissue histology was intact despite some mild perturbation at 10 mM. In the buccal epithelial cell line, TR146, changes in cell parameters were also seen at 1.5 mM over 60 min for both agents, with slightly more sensitivity seen for DC. In isolated porcine buccal epithelial mucosae, GDC was slightly more potent and efficacious than DC at increasing the Papp of [14C]-mannitol. It also increased the Papp of [3H]-octreotide and FITC-LKP by ∼3-fold across porcine buccal tissue without causing damage. Overall, GDC and DC were efficacious in intestinal and buccal models. Both cause mild perturbation leading to an increase in paracellular fluxes for hydrophilic molecules including peptides. Their moderate efficacy, low potency, and low toxicity in these models are similar to that of more established PEs in clinical trials.

Impact of gastrointestinal tract variability on oral drug absorption and pharmacokinetics: An UNGAP review

The absorption of oral drugs is frequently plagued by significant variability with potentially serious therapeutic consequences. The source of variability can be traced back to interindividual variability in physiology, differences in special populations (age- and disease-dependent), drug and formulation properties, or food-drug interactions. Clinical evidence for the impact of some of these factors on drug pharmacokinetic variability is mounting: e.g. gastric pH and emptying time, small intestinal fluid properties, differences in pediatrics and the elderly, and surgical changes in gastrointestinal anatomy. However, the link of colonic factors variability (transit time, fluid composition, microbiome), sex differences (male vs. female) and gut-related diseases (chronic constipation, anorexia and cachexia) to drug absorption variability has not been firmly established yet. At the same time, a way to decrease oral drug pharmacokinetic variability is provided by the pharmaceutical industry: clinical evidence suggests that formulation approaches employed during drug development can decrease the variability in oral exposure. This review outlines the main drivers of oral drug exposure variability and potential approaches to overcome them, while highlighting existing knowledge gaps and guiding future studies in this area.

PAMPA model of gliclazide permeability: The impact of probiotic bacteria and bile acids

Gut microbiota and bile acids possess the ability to modify absorption and pharmacokinetic profile of numerous drugs. Since the variability of gliclazide response in patients cannot be explained only by genetic factors, the influence of gut microbiota and bile acids should be considered. The aim of this study was to determine the effects of probiotic bacteria and bile acids on the gliclazide permeability. The permeability of gliclazide with and without probiotic bacteria and bile acids (cholic acid, CA and deoxycholic acid, DCA) was tested using in vitro PAMPA model, at three different pH values (5.8, 6.5 and 7.4). Concentrations of gliclazide were determined by HPLC analysis. The interactions of gliclazide and bile acids were also investigated by molecular mechanics calculations (MM2). Probiotic bacteria significantly increased the permeability of gliclazide across the PAMPA membrane at all observed pH values while the total amount of gliclazide during incubation with bacteria was significantly reduced at pH 7.4, which could be a consequence of partial metabolism of the drug by enzymes of probiotic bacteria. Bile acids decreased the permeability of gliclazide through PAMPA membrane, with more pronounced effects of DCA, by forming more stable complexes with gliclazide. Given that probiotic bacteria and bile acids are naturally present in the gut and that each individual has a specific bacterial fingerprint, future research should extend the explanation of their effect on the gliclazide bioavailability and therapy individualization in in vivo conditions.

Bile Acid Tethered Docetaxel-Based Nanomicelles Mitigate Tumor Progression through Epigenetic Changes

In this study, we describe the engineering of sub-100 nm nanomicelles (DTX-PC NMs) derived from phosphocholine derivative of docetaxel (DTX)-conjugated lithocholic acid (DTX-PC) and poly(ethylene glycol)-tethered lithocholic acid. Administration of DTX-PC NMs decelerate tumor progression and increase the mice survivability compared to Taxotere (DTX-TS), the FDA-approved formulation of DTX. Unlike DTX-TS, DTX-PC NMs do not cause any systemic toxicity and slow the decay rate of plasma DTX concentration in rodents and non-rodent species including non-human primates. We further demonstrate that DTX-PC NMs target demethylation of CpG islands of Sparcl1 (a tumor suppressor gene) by suppressing DNA methyltransferase activity and increase the expression of Sparcl1 that leads to tumor regression. Therefore, this unique system has the potential to improve the quality of life in cancer patients and can be translated as a next-generation chemotherapeutic.

Peptidomimetics Therapeutics for Retinal Disease

Ocular disorders originating in the retina can result in a partial or total loss of vision, making drug delivery to the retina of vital importance. However, effectively delivering drugs to the retina remains a challenge for ophthalmologists due to various anatomical and physicochemical barriers in the eye. This review introduces diverse administration routes and the accordant pharmacokinetic profiles of ocular drugs to aid in the development of safe and efficient drug delivery systems to the retina with a focus on peptidomimetics as a growing class of retinal drugs, which have great therapeutic potential and a high degree of specificity. We also discuss the pharmacokinetic profiles of small molecule drugs due to their structural similarity to small peptidomimetics. Lastly, various formulation strategies are suggested to overcome pharmacokinetic hurdles such as solubility, retention time, enzymatic degradation, tissue targeting, and membrane permeability. This knowledge can be used to help design ocular delivery platforms for peptidomimetics, not only for the treatment of various retinal diseases, but also for the selection of potential peptidomimetic drug targets.

Bile acids and their receptors in metabolic disorders

Bile acids are a large family of atypical steroids which exert their functions by binding to a family of ubiquitous cell membrane and nuclear receptors. There are two main bile acid activated receptors, FXR and GPBAR1, that are exclusively activated by bile acids, while other receptors CAR, LXRs, PXR, RORγT, S1PR2and VDR are activated by bile acids in addition to other more selective endogenous ligands. In the intestine, activation of FXR and GPBAR1 promotes the release of FGF15/19 and GLP1 which integrate their signaling with direct effects exerted by theother receptors in target tissues. This network is tuned in a time ordered manner by circadian rhythm and is critical for the regulation of metabolic process including autophagy, fast-to-feed transition, lipid and glucose metabolism, energy balance and immune responses. In the last decade FXR ligands have entered clinical trials but development of systemic FXR agonists has been proven challenging because their side effects including increased levels of cholesterol and Low Density Lipoproteins cholesterol (LDL-c) and reduced High-Density Lipoprotein cholesterol (HDL-c). In addition, pruritus has emerged as a common, dose related, side effect of FXR ligands. Intestinal-restricted FXR and GPBAR1 agonists and dual FXR/GPBAR1 agonists have been developed. Here we review the last decade in bile acids physiology and pharmacology.

Physiology and Physical Chemistry of Bile Acids

Bile acids (BAs) are facial amphiphiles synthesized in the body of all vertebrates. They undergo the enterohepatic circulation: they are produced in the liver, stored in the gallbladder, released in the intestine, taken into the bloodstream and lastly re-absorbed in the liver. During this pathway, BAs are modified in their molecular structure by the action of enzymes and bacteria. Such transformations allow them to acquire the chemical-physical properties needed for fulling several activities including metabolic regulation, antimicrobial functions and solubilization of lipids in digestion. The versatility of BAs in the physiological functions has inspired their use in many bio-applications, making them important tools for active molecule delivery, metabolic disease treatments and emulsification processes in food and drug industries. Moreover, moving over the borders of the biological field, BAs have been largely investigated as building blocks for the construction of supramolecular aggregates having peculiar structural, mechanical, chemical and optical properties. The review starts with a biological analysis of the BAs functions before progressively switching to a general overview of BAs in pharmacology and medicine applications. Lastly the focus moves to the BAs use in material science.

Initial In Vivo Evaluation of a Novel Amikacin-Deoxycholate Hydrophobic Salt Delivers New Insights on Amikacin Partition in Blood and Tissues

In this study, an initial in vivo evaluation of a new amikacin-deoxycholate hydrophobic salt aimed at potentiating amikacin action against hard-to-treat lung infections was undertaken by quantifying, for the first time, amikacin in whole blood. Pharmacokinetic evaluation after intranasal administration in a murine model showed higher drug retention in the lungs compared to blood, with no significant differences between the salt and the free drug. Upon repeated administrations, the two treatments resulted in nonsignificant tissue damage and mild higher inflammation for the hydrophobic salt. Whole-blood analysis highlighted an unreported high partition of amikacin in blood components up to 48 h, while significant lung levels were measured up to 72 h. Such a new observation was considered responsible for the nearly overlapping pharmacokinetic profiles of the two treatments. To overcome such an issue, a dry powder in an inhalable form may be best suited. Moreover, if confirmed in humans, and considering the current once-a-day regimen for amikacin aerosols, important yet-to-be-explored clinical implications may be postulated for such amikacin persistence in the organism.

CPE-DB: An Open Database of Chemical Penetration Enhancers

The cutaneous delivery route currently accounts for almost 10% of all administered drugs and it is becoming more common. Chemical penetration enhancers (CPEs) increase the transport of drugs across skin layers by different mechanisms that depend on the chemical nature of the penetration enhancers. In our work, we created a chemical penetration enhancer database (CPE-DB) that is, to the best of our knowledge, the first CPE database. We collected information about known enhancers and their derivatives in a single database, and classified and characterized their molecular diversity in terms of scaffold content, key chemical moieties, molecular descriptors, etc. CPE-DB can be used for virtual screening and similarity search to identify new potent and safe enhancers, building quantitative structure-activity relationship (QSAR) and quantitative structure-property relationship (QSPR) models, and other machine-learning (ML) applications for the prediction of biological activity.

Advances in Oral Subunit Vaccine Design

Many pathogens invade the host at the intestinal surface. To protect against these enteropathogens, the induction of intestinal secretory IgA (SIgA) responses is paramount. While systemic vaccination provides strong systemic immune responses, oral vaccination is the most efficient way to trigger protective SIgA responses. However, the development of oral vaccines, especially oral subunit vaccines, is challenging due to mechanisms inherent to the gut. Oral vaccines need to survive the harsh environment in the gastrointestinal tract, characterized by low pH and intestinal proteases and need to reach the gut-associated lymphoid tissues, which are protected by chemical and physical barriers that prevent efficient uptake. Furthermore, they need to surmount default tolerogenic responses present in the gut, resulting in suppression of immunity or tolerance. Several strategies have been developed to tackle these hurdles, such as delivery systems that protect vaccine antigens from degradation, strong mucosal adjuvants that induce robust immune responses and targeting approaches that aim to selectively deliver vaccine antigens towards specific immune cell populations. In this review, we discuss recent advances in oral vaccine design to enable the induction of robust gut immunity and highlight that the development of next generation oral subunit vaccines will require approaches that combines these solutions.

Microencapsulation of Coenzyme Q10 and bile acids using ionic gelation vibrational jet flow technology for oral delivery

Developing new delivery dosage forms with robust delivery and safety profiles remains a challenge to the pharmaceutical industry in terms of optimum gut absorption, consistent dosing and bioavailability; particularly for orally administered drugs that are poorly water soluble. Coenzyme Q10 is an example of a poorly water-soluble compound with low bioavailability, and significant inter-individual variation after oral administration; limiting its optimum efficacy, as a powerful antioxidant with significant promise in treating hearing disorders. Microencapsulation technology is one way to optimize drug bioavailability and absorption profile. One example is Ionic Gelation Vibrational Jet Flow techniques, using new encapsulating parameters to determine the nature of formed capsules. Bile acids are an example of an excipient that can be used to improve membrane permeability; and will be examined. This review addresses the applications of microencapsulation technology on oral delivery and efficacy profiles of poorly water-soluble drugs, focusing on Coenzyme Q10.

Bioinspired Composite, pH-Responsive Sodium Deoxycholate Hydrogel and Generation 4.5 Poly(amidoamine) Dendrimer Improves Cancer Treatment Efficacy via Doxorubicin and Resveratrol Co-Delivery

Maximizing the antitumor efficacy of doxorubicin (DOX) with a new drug delivery strategy is always desired in the field of biomedical science. Because the clinical applications of DOX in the treatment of cancer is limited by the side effects related to the dose. Herein, we report the co-loading of DOX and resveratrol (RESV) using an injectable in situ formed sodium deoxycholate hydrogel (Na-DOC-hyd) at the pH of the tumor extracellular microenvironment. The sequential, controlled, and sustained release of RESV and DOX for synergistic antitumor effects was confirmed by entrapping G4.5-DOX in the RESV-loaded Na-DOC hydrogel (Na-DOC-hyd-RESV). The synergistic antitumor activity of Na-DOC-hyd-RESV+G4.5-DOX was assessed on HeLa cell xenograft tumor in BALB/c nude mice. In the MTT biocompatibility assay, both the G4.5 PAMAM dendrimer and Na-DOC-hyd exhibited negligible cytotoxicity up to the highest dose of 2.0 mg mL-1 in HeLa, MDA-MB-231, and HaCaT cells. The release profiles of DOX and RESV from the Na-DOC-hyd-RESV+G4.5-DOX confirmed the relatively rapid release of RESV (70.43 ± 1.39%), followed by that of DOX (54.58 ± 0.62%) at pH 6.5 in the 7 days of drug release studies. A single intratumoral injection of Na-DOC-hyd-RESV+G4.5-DOX maximally suppressed tumor growth during the 28 days of the treatment period. Na-DOC-hyd-RESV+G4.5-DOX did not cause any histological damage in the major visceral organs. Therefore, this Na-DOC-hydrogel for dual drugs (DOX and RESV) delivery at the pH of the tumor extracellular microenvironment is a promising, safe, and effective combination for antitumor chemotherapy.

Improvements in the Oral Absorption and Anticancer Efficacy of an Oxaliplatin-Loaded Solid Formulation: Pharmacokinetic Properties in Rats and Nonhuman Primates and the Effects of Oral Metronomic Dosing on Colorectal Cancer

Objective

The anticancer efficacy of orally administered chemotherapeutics is often constrained by low intestinal membrane permeability and oral bioavailability. In this context, we designed a solid oral formulation of oxaliplatin (OP), a third-generation cisplatin analog, to improve oral bioavailability and investigate its application in metronomic chemotherapy.

Methods

An ion-pairing complex of OP with a permeation enhancer, N^α-deoxycholyl-l-lysyl-methylester (DLM), was successfully prepared and then mixed with dispersing agents (including poloxamer 188 and Labrasol) to form the solid, amorphous oral formulation OP/DLM (OP/DLM-SF; hereafter, ODSF).

Results

The optimized powder formulation was sized in the nanoscale range (133±1.47 nm). The effective permeability of OP increased by 12.4-fold after ionic complex formation with DLM and was further increased by 24.0-fold after incorporation into ODSF. ODSF exhibited respective increases of 128% and 1010% in apparent permeability across a Caco-2 monolayer, compared to OP/DLM and OP. Furthermore, inhibition of bile acid transporters by actinomycin D and caveola-mediated uptake by brefeldin in Caco-2 cell monolayers reduced the apparent permeability values of ODSF by 58.4% and 51.1%, respectively, suggesting predominant roles for bile acid transporters and caveola-mediated transport in intestinal absorption of ODSF. In addition, macropinocytosis and paracellular and transcellular passive transport significantly influenced the intestinal permeation of ODSF. The oral bioavailabilities of ODSF in rats and monkeys were 68.2% and 277% higher, respectively, than the oral bioavailability of free OP. In vivo analyses of anticancer efficacy in CT26 and HCT116 cell-bearing mice treated with ODSF demonstrated significant suppression of tumor growth, with respective maximal tumor volume reductions of 7.77-fold and 4.07-fold, compared to controls.

Conclusion

ODSF exhibits therapeutic potential, constituting an effective delivery system that increases oral bioavailability, with applications to metronomic chemotherapy.

The role of gut microbiota (GM) and GM-related metabolites in diabetes and obesity. A review of analytical methods used to measure GM-related metabolites in fecal samples with a focus on metabolites' derivatization step

Disruption of gut microbiota (GM) composition is increasingly related to the pathogenesis of various metabolic diseases. Additionally, GM is responsible for the production and transformation of metabolites involved in the development of metabolic disorders, such as obesity and type 2 diabetes mellitus (T2DM). The current state of knowledge regarding the composition of GM and GM-related metabolites in relation to the progress and development of obesity and T2DM is presented in this review. To understand the relationships between GM-related metabolites and the development of metabolic disorders, their accurate qualitative and quantitative measurement in biological samples is needed. Feces represent a valuable biological matrix which composition may reflect the health status of the lower gastrointestinal tract and the whole organism. Mass spectrometry (MS), mainly in combination with gas chromatography (GC) or liquid chromatography (LC), is commonly used to measure fecal metabolites. However, profiling metabolites in such a complex matrix as feces is challenging from both analytical chemistry and biochemistry standpoints. Chemical derivatization is one of the most effective methods used to overcome these problems. In this review, we provide a comprehensive summary of the derivatization methods of GM-related metabolites prior to GC-MS or LC-MS analysis, which have been published in the last five years (2015-2020). Additionally, analytical methods used for the analysis of GM-related metabolites without the derivatization step are also presented.

The Impact of Formulation on Lutein, Zeaxanthin, and meso-Zeaxanthin Bioavailability: A Randomised Double-Blind Placebo-Controlled Study

Lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) have been the focus of research and commercial interest for their applications in human health. Research into formulations to enhance their bioavailability is merited. This 6 month randomised placebo-controlled trial involving 81 healthy volunteers compared the bioavailability of different formulations of free L, Z, and MZ in sunflower or omega-3 oil versus L, Z, and MZ diacetates (Ld, Zd, and MZd) in a micromicellar formulation. Fasting serum carotenoids, macular pigment, and skin carotenoid score were analysed at baseline and 6 months. Serum L, Z, and MZ concentrations increased in all active interventions compared to placebo (p < 0.001 to p = 0.008). The diacetate micromicelle formulation exhibited a significantly higher mean response in serum concentrations of Z and MZ compared to the other active interventions (p = 0.002 to 0.019). A micromicellar formulation with solubilised Z and MZ diacetates is a promising technology advancement that enhances the bioavailability of these carotenoids when compared to traditional carotenoid formulations (ISRCTN clinical trial registration number: ISRCTN18206561).

Apical sodium-dependent bile acid transporter, drug target for bile acid related diseases and delivery target for prodrugs: Current and future challenges

Apical Sodium-dependent Bile Acid Transporter (ASBT) actively reabsorbs bile acids (BAs) from the gut lumen. This process is a critical step in the enterohepatic circulation (EHC) of BAs and plays important roles in the homeostasis of BAs in the body. Therefore, ASBT is considered a favorite target for intervention to regulate the levels of BAs, cholesterol, lipid and glucose etc. In addition, ASBT is also a popular delivery target for developing prodrugs, due to its intestinal localization, high expression and high uptake capacity. In the past ten years, ASBT has been the focus by both academia and pharmaceutical industry as research targets not only for BA-related diseases but also for prodrug delivery. Numerous studies have been published and many candidate ASBT inhibitors are being developed. Here we review and summarize the current states of ASBT research with a focus on the therapeutic applications of ASBT as a target for therapy as well as a delivery target for prodrugs. The current and future challenges in ASBT research and outlook of drug developments are discussed.

Bile acid transporter-mediated oral drug delivery

Bile acids are synthesized in the liver, stored in the gallbladder, and secreted into the duodenum at meals. Apical sodium-dependent bile acid transporter (ASBT), an ileal Na⁺-dependent transporter, plays the leading role of bile acid absorption into enterocytes, where bile acids are delivered to basolateral side by ileal bile acid binding protein (IBABP) and then released by organic solute transporter OSTα/β. The absorbed bile acids are delivered to the liver via portal vein. In this process called "enterohepatic recycling", only 5% of the bile acid pool (~3 g in human) is excreted in feces, indicating the large recycling capacity and high transport efficacy of ASBT-mediated absorption. Therefore, bile acid transporter-mediated oral drug delivery has been regarded as a feasible and potential strategy to improve the oral bioavailability. This review introduces the key factors in enterohepatic recycling, especially the mechanism of bile acid uptake by ASBT, and the development of bile acid-based oral drug delivery for ASBT-targeting, including bile acid-based prodrugs, bile acid/drug electrostatic complexation and bile acid-containing nanocarriers. Furthermore, the specific transport pathways of bile acid in enterocytes are described and the recent finding of lymphatic delivery of bile acid-containing nanocarriers is discussed.

Safety of Probiotics: Functional Fruit Beverages and Nutraceuticals

Over the last decade, fruit juice consumption has increased. Their rise in popularity can be attributed to the belief that they are a quick way to consuming a dietary portion of fruit. Probiotics added to fruit juices produce various bioactive compounds, thus probiotic fruit juices can be considered as a new type of functional foods. Such combinations could improve nutritional properties and provide health benefits of fruit juices, due to delivering positive health attributes from both sources (fruit juices and probiotics). However, this review discusses the other side of the same coin, i.e., the one that challenges general beliefs that probiotics are undoubtedly safe. This topic deserves more acknowledgments from the medical and nutritional literature, as it is highly important for health care professionals and nutritionists who must be aware of potential probiotic issues. Still, clinical trials have not adequately questioned the safety of probiotics, as they are generally considered safe. Therefore, this reviews aims to give an evidence-based perspective of probiotic safety, focusing on probiotic fruit beverages and nutraceuticals, by providing documented clinical case reports and studies. Finally, the paper deals with some additional insights from the pharmacological and toxicological point of views, such as pharmacological repercussions of probiotics on health.

Evaluating the Efficacy of Taurodeoxycholic Acid in Providing Otoprotection Using an in vitro Model of Electrode Insertion Trauma

Cochlear implants (CIs) are widely used to provide auditory rehabilitation to individuals having severe to profound sensorineural hearing loss (SNHL). However, insertion of electrode leads to inner trauma and activation of inflammatory and apoptotic signaling cascades resulting in loss of residual hearing in implanted individuals. Pharmaceutical interventions that can target these signaling cascades hold great potential for preserving residual hearing by preventing sensory cell damage. Bile salts have shown efficacy in various regions of the body as powerful antioxidants and anti-inflammatory agents. However, their efficacy against inner ear trauma has never been explored. The objective of this study was to determine whether taurodeoxycholic acid (TDCA), a bile salt derivative, can prevent sensory cell damage employing an in vitro model of electrode insertion trauma (EIT). The organ of Corti (OC) explants were dissected from postnatal day 3 (P-3) rats and placed in serum-free media. Explants were divided into control and experimental groups: (1) untreated controls; (2) EIT; (3) EIT+ TDCA (different concentrations). Hair cell (HC) density, analyses of apoptosis pathway (cleaved caspase 3), levels of reactive oxygen species (ROS) as well as inducible nitric oxide synthase (iNOS) activity and Mitochondrial Membrane Potential (MMP) were assayed. Treatment with TDCA provided significant otoprotection against HC loss in a dose-dependent manner. The molecular mechanisms underlying otoprotection involved decreasing oxidative stress, lowering levels of iNOS, and abrogating generation of cleaved caspase 3. The results of the present study suggest that TDCA provides efficient otoprotection against EIT, in vitro and should be explored for developing pharmaceutical interventions to preserve residual hearing post-cochlear implantation.

The influence of probiotics on bile acids in diseases and aging

Recent evidence indicates the use of probiotics in the prevention and treatment of diseases. Probiotics are capable of changing the gut microbiota composition and bile acid synthesis to elicit health benefits such as cholesterol-lowering, weight reduction, and improving insulin sensitivity. The aging population is prone to develop diseases because of their decreased physiological and biological systems. Probiotics are one of the promising supplements that may potentially counteract these detrimental effects. This review will discuss the influence of probiotics on bile acids in different populations-the elderly, obese individuals, and those with hypercholesterolemia, type 2 diabetes, hypertension, and non-alcoholic fatty liver disease.