Gliclazide reduces MKC intestinal transport in healthy but not diabetic rats

Low-dose nano-gel incorporated with bile acids enhanced pharmacology of surgical implants

Aim: Major challenges to islet transplantation in Type 1 diabetes include host-inflammation, which results in failure to maintain survival and functions of transplanted islets. Therefore, this study investigated the applications of encapsulating the bile acid ursodeoxycholic acid (UDCA) with transplanted islets within improved nano-gel systems for Type 1 diabetes treatment. Materials & methods: Islets were harvested from healthy mice, encapsulated using UDCA-nano gel and transplanted into the diabetic mice, while the control group was transplanted encapsulated islets without UDCA. The two groups' survival plot, blood glucose, and inflammation and bile acid profiles were analyzed. Results & conclusion: UDCA-nano gel enhanced survival, glycemia and normalized bile acids' profile, which suggests improved islets functions and potential adjunct treatment for insulin therapy.

Taurine Grafted Micro-Implants Improved Functions without Direct Dependency between Interleukin-6 and the Bile Acid Lithocholic Acid in Plasma

A recent study showed an association between diabetes development and the bile acid lithocholic acid (LCA), while another study demonstrated positive biological effects of the conjugated bile acid, taurocholic acid (TCA), on pancreatic cells. Thus, this study aimed to encapsulate TCA with primary islets (graft) and study the biological effects of the graft, post-transplantation, in diabetic mice, including effects on LCA concentrations. Sixteen mature adult mice were made diabetic and randomly divided into two equal groups, control and test (transplanted encapsulated islets without or with TCA). Graft pharmaceutical features pre-transplantation, and biological effects including on LCA concentrations post-transplantation, were measured. TCA-microcapsules had an oval shape and similar size compared with the control. The treatment group survived longer, showed improved glucose and interleukin-6 concentrations, and lower LCA concentrations in plasma, large intestine, faeces, liver and spleen, compared with control. Results suggest that TCA incorporation with islets encapsulated graft exerted beneficial effects, but there was no direct and significant dependency between concentrations of interleukin-6 and LCA.

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.

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.

Gliclazide: Biopharmaceutics Characteristics to Discuss the Biowaiver of Immediate and Extended Release Tablets

The lists of essential medicines of the World Health Organization (WHO) and Brazil include gliclazide as an alternative to the oral antidiabetic drug of first choice, metformin, in the treatment of type 2 diabetes mellitus because of its pharmacokinetic profile and few side effects. Thus, it is also considered by WHO and the International Pharmaceutical Federation (FIP) as a drug candidate to biowaiver, which is the evaluation of how favorable the biopharmaceutics characteristics are in order to obtain waiver from the relative bioavailability/bioequivalence (RB/BE) studies to register new medicines. This paper presents a review about the solubility, permeability and dissolution of gliclazide. A critical analysis of the information allowed to identify gliclazide as a Biopharmaceutics Classification System (BCS) Class II drug. Therefore, new drugs in immediate release dosage forms will not be eligible for biowaiver. Regarding the extended release dosage forms, besides the limited solubility, no information on the comparative dissolution profile was found, which would be necessary to analyze a possible biowaiver for a smaller dosage. It can be concluded that the registration of new medicines containing gliclazide must undergo RB/BE studies, since there is not enough evidence to recommend the replacement and waiver of such studies for immediate and extended release formulations.

Alginate-based drug oral targeting using bio-micro/nano encapsulation technologies

INTRODUCTION

Oral delivery is the most common administrated drug delivery path. However, oral administration of lipophilic drugs has some limitations: they have poor dose-response due to low and varied dissolution kinetics and oral bioavailability with sub-optimal dissolution within the aqueous gastrointestinal microenvironment. Therefore, there is a need for robust formulating methods that protect the drug until it reaches to its optimum absorption site, allowing its optimum pharmacological effects via increasing its intestinal permeation and bioavailability.

AREA COVERED

Herein, we provide insights on orally administered lipophilic drug delivery systems. The detailed description of the obstacles associated with the oral bioavailability of lipophilic drugs are also discussed. Following this, techniques to overcome these obstacles with much emphasis on optimal safety and efficacy are addressed. Newly designed ionic vibrational jet flow encapsulation technology has enormous growth in lipophilic drug delivery systems, which is discussed thereafter.

EXPERT OPINION

Researchers have shown interest in drug's encapsulation. A combination of drug-bile acid and microencapsulation methods can be one promising strategy to improve the oral delivery of lipophilic drugs. However, the most critical aspect of this approach is the selection of bile acids, polymer, and encapsulation technology.

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.

Histological effects of pharmacologically active human bile acid nano/micro-particles in Type-1 diabetes

Aim: Gliclazide (G) is a drug prescribed for Type 2 diabetics, although recent studies suggest it has desirable effects in both types of diabetes, Type 1 diabetes and Type 2 diabetes. G has an inconsistent absorption due to poor formulation and bile acids (BAs) have shown significant promise in drug formulation optimization. Hence, the study aimed to examine G effects on histopathological, anti-inflammatory and antidiabetic effects when encapsulated with BAs. Materials & methods: Rats were randomized into eight groups, of which seven were made Type 1 diabetes and treated with various BA-based treatments. Tissue histopathology, inflammation and the bile acid profile were analyzed. Results & conclusion: G capsules showed no histological but the most anti-inflammatory effects, which suggest significant beneficial effects in diabetes treatment.

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.

Probucol-poly(meth)acrylate-bile acid nanoparticles increase IL-10, and primary bile acids in prediabetic mice

Aim: Common features in insulin-resistance diabetes include inflammation and liver damage due to bile acid accumulation. Results & methodology: This study aimed to test in vivo pharmacological effects of combining two drugs, ursodeoxycholic acid that has bile acid regulatory effects, and probucol (PB) that has potent anti-oxidative stress effects, using a new poly(meth)acrylate nano-targeting formulation on prediabetic mice. Mice were made diabetic and were fed daily with either PB, nanoencapsulated PB or nanoencapsulated PB-ursodeoxycholic acid before blood, tissues, urine and feces were collected for inflammation and bile acid measurements. The nanoencapsulated PB-ursodeoxycholic acid formulation increased plasma IL-10, and increased the concentration of primary bile acids in the liver and heart. Conclusion: Results suggest potential applications in regulating IL-10 in insulin-resistance prediabetes.

Pharmacological effects of nanoencapsulation of human-based dosing of probucol on ratio of secondary to primary bile acids in gut, during induction and progression of type 1 diabetes

INTRODUCTION

The ratio of secondary to primary bile acids changes during Type 1 Diabetes (T1D) development and these effects might be ameliorated by using cholesterol lowering drugs or hydrophilic bile acids. Probucol is a cholesterol-lowering drug, while ursodeoxycholic acid is a hydrophilic bile acid. This study investigated whether nanoencapsulated probucol with ursodeoxycholic acid altered bile acid ratios and the development of diabetes.

METHODS

Balb/c mice were divided into three groups and gavaged daily with either free probucol, nanoencapsulated probucol or nanoencapsulated probucol with ursodeoxycholic acid for seven days. Alloxan was injected and once T1D was confirmed the mice continued to receive daily gavages until euthanasia. Blood, tissues, faeces and urine were collected for analysis of insulin and bile acids.

RESULTS AND CONCLUSIONS

Nanoencapsulated probucol-ursodeoxycholic acid resulted in significant levels of insulin in the blood, lower levels of secondary bile acids in liver and lower levels of primary bile acids in brain, while ratio of secondary to primary bile acids remains similar among all groups, except in the faeces. Findings suggests that nanoencapsulated probucol-ursodeoxycholic acid may exert a protective effect on pancreatic β-cells and reserve systemic insulin load via modulation of bile acid concentrations in the liver and brain.

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.

Morphological, Stability, and Hypoglycemic Effects of New Gliclazide-Bile Acid Microcapsules for Type 1 Diabetes Treatment: the Microencapsulation of Anti-diabetics Using a Microcapsule-Stabilizing Bile Acid

When we administered orally a mixture of the anti-diabetic drug, gliclazide (G) and a primary bile acid, they exerted a hypoglycemic effect in a rat model of type 1 diabetes (T1D), but stability of mixture was limited. We aimed to develop and characterize microcapsules incorporating G with a microcapsule-stabilizing bile acid, ursodeoxycholic acid (UDCA). Sodium alginate (SA)-based microcapsules were prepared with either G or G with UDCA and analyzed in terms of morphological, physico-chemical, and electro-chemical characteristics at different pH and temperatures. The microcapsules' effects on viability on muscle cell line (C2C12) and on diabetic rats' blood glucose levels and inflammatory profiles were also examined. Bile acid-based microcapsules maintained their morphology, showed good stability, and compatibility profiles, and the incorporation of UDCA resulted in less G content per microcapsule (p < 0.01) and production of stronger microcapsules that were more resistant to mechanical pressure (p < 0.01). G-UDCA-SA microcapsules enhanced muscle cell viability at higher glucose concentrations compared with control (G-SA and UDCA-SA), and they had strong anti-inflammatory effects on diabetic rats. In addition, the incorporation of UDCA into G microcapsules enhanced the physical characteristics of the microcapsules and optimized G delivery after oral administration.

Bile Acid Synthesis: From Nature to the Chemical Modification and Synthesis and Their Applications as Drugs and Nutrients

Bile acids (BAs) are amphiphilic molecules with 24 carbon atoms and consist of a hydrophobic and a rigid steroid nucleus, to which are attached a hydrophilic hydroxyl group and a flexible acidic aliphatic side chain. The steroidal core of BAs constitutes a saturated cyclopentanoperhydrophenanthrene skeleton, consisting of three six-membered (A, B, and C) and one five-membered ring (D). Primary BAs are produced in the hepatocytes, while secondary BAs are formed by modifying the primary BAs in the intestinal lumen, i.e., by the reactions of 7α-dehydroxylation and deconjugation of cholic acid (CA) and chenodeoxycholic acid (CDCA). The most important secondary BAs are deoxycholic acid (DCA) and lithocholic acid (LCA). The BAs realize their effects through nuclear farnesoid X receptors (FXRs) and membrane TGR5 receptors. It has been found that BAs are also associated with other receptors such as the vitamin D receptor (VDR), from which the most significant ligand is calcitriol, as well as with pregnane X receptor (PXR) and potentially with the constitutive androstane receptor (CAR), whose ligands are numerous, structurally different xenobiotics that show greater affinity to BAs. The BAs as therapeutic agents (drugs) have the potential to produce beneficial effects in cases of sexually transmitted diseases, primary biliary cirrhosis (PBC), primary sclerosing cholangitis, gallstones, digestive tract diseases, cystic fibrosis, and cancer. Ursodeoxycholic acid (UDCA) was the only drug approved by the US Food and Drug Administration (FDA) for the treatment of PBC. In this paper, the different pathways of bile acid biosynthesis are explained as well as chemical modifications and the synthesis of different keto derivatives of BAs. Also, the effects of BAs on digestion of nutrients, their role as drugs, and, in particular, the emphasis on the hypoglycemic properties of 7α, 12α-dihydroxy−12–keto−5β-cholanic acid in the treatment of diabetes mellitus are examined in detail.

High-Loading Dose of Microencapsulated Gliclazide Formulation Exerted a Hypoglycaemic Effect on Type 1 Diabetic Rats and Incorporation of a Primary Deconjugated Bile Acid, Diminished the Hypoglycaemic Antidiabetic Effect

BACKGROUND AND OBJECTIVE

Gliclazide is a drug commonly used in type 2 diabetes mellitus. Recently, gliclazide has shown desirable pharmacological effects such as immunoregulatory and anti-clotting effects, which suggests potential applications in type 1 diabetes mellitus (T1DM). Gliclazide has variable absorption after oral administration, and thus using targeted-delivery techniques, such as microencapsulation, may optimise gliclazide absorption and potential applications in T1DM. Bile acids such as cholic acid have shown microcapsule-stabilising and controlled-release effects, and thus their incorporation into gliclazide microcapsules may further optimise gliclazide release, absorption and antidiabetic effects. Accordingly, this study aimed to examine the hypoglycaemic effects of gliclazide microcapsules with and without cholic acid, in a rat model of T1DM.

METHODS

Thirty-five alloxan-induced T1DM rats were randomly divided into five equal groups and gavaged a single dose of empty microcapsules, gliclazide, gliclazide microcapsules, gliclazide-cholic acid or gliclazide-cholic acid microcapsules. Blood samples were collected over 10 h post-dose and analysed for blood glucose and gliclazide serum concentrations.

RESULTS

Gliclazide microcapsules exerted a hypoglycaemic effect in the diabetic rats, and cholic acid incorporation diminished the hypoglycaemic effects, which suggests the lack of synergistic effects between gliclazide and cholic acid. In addition, neither microencapsulation nor cholic acid incorporation optimised gliclazide absorption which suggests that hypoglycaemic effects of gliclazide are independent of its absorption and serum concentrations. This also suggests that hypoglycaemic effects of gliclazide may be associated with gut-metabolic activation rather than gut-targeted delivery and systemic absorption.

CONCLUSION

Gliclazide microcapsules exerted hypoglycaemic effects in T1DM rats independent of insulin and thus may have potentials in treatment of T1DM.

Diabetes development increased concentrations of the conjugated bile acid, taurocholic acid in serum, while treatment with microencapsulated-taurocholic acid exerted no hypoglycaemic effects

CONTEXT

The bile acid taurocholic acid (TCA) is endogenously produced, and has shown formulation-stabilising effects when incorporated into microcapsules containing potential antidiabetic drugs. This study aimed to develop and characterise TCA-microcapsules, and test their antidiabetic effects, in an animal model of Type 1 diabetes (T1D).

METHODS

Using the polymer sodium alginate (SA), SA-microcapsules (control) and TCA-microcapsules (test) were prepared, and assessed for morphology, surface composition, chemical and thermal stability, swelling, buoyancy, mechanical, release and rheological properties. TCA-microcapsules were gavaged as a single dose (1.2mg/300g) to alloxan-induced diabetic rats, and blood glucose and TCA concentrations in serum, tissues (ileum, liver and pancreas) and faeces, were measured. One healthy and one diabetic group were used as control and gavaged SA-microcapsules.

RESULTS

TCA-microcapsules showed consistent size, TCA presence on surface and all layers of microcapsules, chemical and thermal stability, enhanced swelling, buoyancy and targeted-release properties and rheological analysis showed Non-Newtonian flow properties. TCA serum concentrations were lower in the healthy group, compared with the diabetic and diabetic-treated groups, but there was no significant difference between diabetic control and diabetic treated groups, in terms of TCA levels, and blood glucose concentrations.

CONCLUSIONS

The developed TCA-microcapsules showed good stability and release properties, but did not lower blood glucose levels in T1D, which suggests absence of insulin-mimetic effects, when using a single 1.2mg/rat oral dose.

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.

A comprehensive study of novel microcapsules incorporating gliclazide and a permeation enhancing bile acid: hypoglycemic effect in an animal model of Type-1 diabetes

CONTEXT

Gliclazide (G) is a commonly prescribed drug for Type 2 diabetes (T2D). In a recent study, we found that when G was combined with a primary bile acid, and gavaged to an animal model of Type 1 diabetes (T1D), it exerted a hypoglycemic effect. We hypothesized this to be due to metabolic activation of the primary bile acid into a secondary or a tertiary bile acid, which enhanced G solubility and absorption. The tertiary bile acid, taurocholic acid (TCA), has shown strong permeation-enhancing effects in vivo. Thus, we aimed to design, characterize, and test microcapsules incorporating G and TCA in an animal model of T1D.

METHODS

Microcapsules were prepared using the polymer sodium alginate (SA). G-SA microcapsules (control) and G-TCA-SA microcapsules (test) were extensively examined (in-vitro) at different pH and temperatures. The microcapsules were gavaged to diabetic rats, and blood glucose and G concentrations in serum were examined. Ex-vivo studies were also performed using a muscle cell line (C2C12), and cell viability and glucose intake post-treatment were examined.

RESULTS

G-TCA-SA microcapsules showed good stability, uniformity, and thermal and chemical excipient compatibilities. TCA did not change the size or the shape of the microcapsules, but it enhanced their mechanical resistance and reduced their swelling properties. G-TCA-SA enhanced the viability of C2C12 cells over 24 hours, and exerted a hypoglycemic effect in alloxan-induced type-1 diabetic rats.

CONCLUSIONS

The incorporation of TCA into G-microcapsules resulted in functionally improved microcapsules with a positive effect on cell viability and glycemic control in Type-1 diabetic animals.

The role of the bile acid chenodeoxycholic acid in the targeted oral delivery of the anti-diabetic drug gliclazide, and its applications in type 1 diabetes

Gliclazide (G) is used to treat type 2 diabetes (T2D), and also has anti-platelet, anti-radical, and anti-inflammatory effects. G has poor water solubility and high inter-individual variations in absorption, limiting its application in type 1 diabetes (T1D). The bile acid, chenodeoxycholic acid (CDCA), has permeation-enhancing effects. Sodium alginate (SA) was used to microencapsulate G and CDCA to produce control (G-SA) and test (G-CDCA-SA) microcapsules. Both microcapsules showed uniform structure, morphology, and good stability profiles. CDCA reduced G-release at pH 7.8, while G-release was negligible at lower pH values in both microcapsules. CDCA incorporation resulted in less swelling and stronger microcapsules, suggesting improved stability.

Swelling, mechanical strength, and release properties of probucol microcapsules with and without a bile acid, and their potential oral delivery in diabetes

We have demonstrated a permeation-enhancing effect of deoxycholic acid (DCA), the bile acid, in diabetic rats. In this study, we designed DCA-based microcapsules for the oral delivery of the antilipidemic drug probucol (PB), which has potential antidiabetic effects. We aimed to further characterize these microcapsules and examine their pH-dependent release properties, as well as the effects of DCA on their stability and mechanical strength at various pH and temperature values. Using the polymer sodium alginate (SA), we prepared PB-SA (control) and PB-DCA-SA (test) microcapsules. The microcapsules were examined for drug content, size, surface composition, release, Micro-CT cross-sectional imaging, stability, Zeta potential, mechanical strength, and swelling characteristics at different pH and temperature values. The microencapsulation efficiency and production yield were also examined. The addition of DCA resulted in microcapsules with a greater density and with reduced swelling at a pH of 7.8 and at temperatures of 25°C and 37°C (p < 0.01). The size, surface composition, production yield, and microencapsulation efficiency of the microcapsules remained similar after DCA addition. PB-SA microcapsules produced multiphasic PB release, while PB-DCA-SA microcapsules produced monophasic PB release, suggesting more controlled PB release in the presence of DCA. The PB-DCA-SA microcapsules showed good stability and a pH-sensitive uniphasic release pattern, which may suggest potential applications in the oral delivery of PB in diabetes.

Probucol release from novel multicompartmental microcapsules for the oral targeted delivery in type 2 diabetes

In previous studies, we developed and characterised multicompartmental microcapsules as a platform for the targeted oral delivery of lipophilic drugs in type 2 diabetes (T2D). We also designed a new microencapsulated formulation of probucol-sodium alginate (PB-SA), with good structural properties and excipient compatibility. The aim of this study was to examine the stability and pH-dependent targeted release of the microcapsules at various pH values and different temperatures. Microencapsulation was carried out using a Büchi-based microencapsulating system developed in our laboratory. Using SA polymer, two formulations were prepared: empty SA microcapsules (SA, control) and loaded SA microcapsules (PB-SA, test), at a constant ratio (1:30), respectively. Microcapsules were examined for drug content, zeta potential, size, morphology and swelling characteristics and PB release characteristics at pH 1.5, 3, 6 and 7.8. The production yield and microencapsulation efficiency were also determined. PB-SA microcapsules had 2.6 ± 0.25% PB content, and zeta potential of -66 ± 1.6%, suggesting good stability. They showed spherical and uniform morphology and significantly higher swelling at pH 7.8 at both 25 and 37°C (p < 0.05). The microcapsules showed multiphasic release properties at pH 7.8. The production yield and microencapsulation efficiency were high (85 ± 5 and 92 ± 2%, respectively). The PB-SA microcapsules exhibited distal gastrointestinal tract targeted delivery with a multiphasic release pattern and with good stability and uniformity. However, the release of PB from the microcapsules was not controlled, suggesting uneven distribution of the drug within the microcapsules.

Advanced bile acid-based multi-compartmental microencapsulated pancreatic β-cells integrating a polyelectrolyte-bile acid formulation, for diabetes treatment

This study utilized the Seahorse Analyzer to examine the effect of the bile acid ursodeoxycholic acid (UDCA), on the morphology, swelling, stability, and size of novel microencapsulated β-cells, in real-time. UDCA was conjugated with fluorescent compounds, and its partitioning within the microcapsules was examined using confocal microscopy. UDCA produced microcapsules with good morphology, better mechanical strength (p < 0.01), and reduced swelling properties (p < 0.01), but lower cell viability (p < 0.05) and cell count per microcapsule (p < 0.01). UDCA reduced the cells' biochemical activities, mitochondrial respiration, and energy production, post-microencapsulation. This is the first time biological functions of microencapsulated β-cells have been analyzed in real-time.

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

The authors have previously designed, developed, and characterized a novel microencapsulated formulation as a platform for the targeted delivery of therapeutics in an animal model of type 2 diabetes, using the drug probucol (PB). The aim of this study was to optimize PB microcapsules by incorporating the bile acid deoxycholic acid (DCA), which has good permeation-enhancing properties, and to examine its effect on microcapsules' morphology, rheology, structural and surface characteristics, and excipients' chemical and thermal compatibilities. Microencapsulation was carried out using a BÜCHI-based microencapsulating system established in the authors' laboratory. Using the polymer sodium alginate (SA), two microencapsulated formulations were prepared: PB-SA (control) and PB-DCA-SA (test) at a constant ratio (1:30 and 1:3:30, respectively). Complete characterization of the microcapsules was carried out. The incorporation of DCA resulted in better structural and surface characteristics, uniform morphology, and stable chemical and thermal profiles, while size and rheological parameters remained similar to control. In addition, PB-DCA-SA microcapsules showed good excipients' compatibilities, which were supported by data from differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray studies, suggesting microcapsule stability. Hence, PB-DCA-SA microcapsules have good rheological and compatibility characteristics and may be suitable for the oral delivery of PB in type 2 diabetes.

Microencapsulation as a novel delivery method for the potential antidiabetic drug, Probucol

Introduction

In previous studies, we successfully designed complex multicompartmental microcapsules as a platform for the oral targeted delivery of lipophilic drugs in type 2 diabetes (T2D). Probucol (PB) is an antihyperlipidemic and antioxidant drug with the potential to show benefits in T2D. We aimed to create a novel microencapsulated formulation of PB and to examine the shape, size, and chemical, thermal, and rheological properties of these microcapsules in vitro.

Method

Microencapsulation was carried out using the Büchi-based microencapsulating system developed in our laboratory. Using the polymer, sodium alginate (SA), empty (control, SA) and loaded (test, PB-SA) microcapsules were prepared at a constant ratio (1:30). Complete characterizations of microcapsules, in terms of morphology, thermal profiles, dispersity, and spectral studies, were carried out in triplicate.

Results

PB-SA microcapsules displayed uniform and homogeneous characteristics with an average diameter of 1 mm. The microcapsules exhibited pseudoplastic-thixotropic characteristics and showed no chemical interactions between the ingredients. These data were further supported by differential scanning calorimetric analysis and Fourier transform infrared spectral studies, suggesting microcapsule stability.

Conclusion

The new PB-SA microcapsules have good structural properties and may be suitable for the oral delivery of PB in T2D. Further studies are required to examine the clinical efficacy and safety of PB in T2D.

Novel artificial cell microencapsulation of a complex gliclazide-deoxycholic bile acid formulation: a characterization study

Gliclazide (G) is an antidiabetic drug commonly used in type 2 diabetes. It has extrapancreatic hypoglycemic effects, which makes it a good candidate in type 1 diabetes (T1D). In previous studies, we have shown that a gliclazide-bile acid mixture exerted a hypoglycemic effect in a rat model of T1D. We have also shown that a gliclazide-deoxycholic acid (G-DCA) mixture resulted in better G permeation in vivo, but did not produce a hypoglycemic effect. In this study, we aimed to develop a novel microencapsulated formulation of G-DCA with uniform structure, which has the potential to enhance G pharmacokinetic and pharmacodynamic effects in our rat model of T1D. We also aimed to examine the effect that DCA will have when formulated with our new G microcapsules, in terms of morphology, structure, and excipients' compatibility. Microencapsulation was carried out using the Büchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) at a ratio of 1:30, and G-DCA-SA (test) at a ratio of 1:3:30. Complete characterization of microcapsules was carried out. The new G-DCA-SA formulation was further optimized by the addition of DCA, exhibiting pseudoplastic-thixotropic rheological characteristics. The size of microcapsules remained similar after DCA addition, and these microcapsules showed no chemical interactions between the excipients. This was supported further by the spectral and microscopy studies, suggesting microcapsule stability. The new microencapsulated formulation has good structural properties and may be useful for the oral delivery of G in T1D.

Characterization of a novel bile acid-based delivery platform for microencapsulated pancreatic β-cells

INTRODUCTION

In a recent study, we confirmed good chemical and physical compatibility of microencapsulated pancreatic β-cells using a novel formulation of low viscosity sodium alginate (LVSA), Poly-L-Ornithine (PLO), and the tertiary bile acid, ursodeoxycholic acid (UDCA). This study aimed to investigate the effect of UDCA on the morphology, swelling, stability, and size of these new microcapsules. It also aimed to evaluate cell viability in the microcapsules following UDCA addition.

MATERIALS AND METHODS

Microencapsulation was carried out using a Büchi-based system. Two (LVSA-PLO, control and LVSA-PLO-UDCA, test) pancreatic β-cells microcapsules were prepared at a constant ratio of 10:1:3, respectively. The microcapsules' morphology, cell viability, swelling characteristics, stability, mechanical strength, Zeta potential, and size analysis were examined. The cell contents in each microcapsule and the microencapsulation efficiency were also examined.

RESULTS

The addition of UDCA did not affect the microcapsules' morphology, stability, size, or the microencapsulation efficiency. However, UDCA enhanced cell viability in the microcapsules 24 h after microencapsulation (p < 0.01), reduced swelling (p < 0.05), reduced Zeta potential (- 73 ± 2 to - 54 ± 2 mV, p < 0.01), and increased mechanical strength of the microcapsules (p < 0.05) at the end of the 24-h experimental period.

DISCUSSION AND CONCLUSION

UDCA increased β-cell viability in the microcapsules without affecting the microcapsules' size, morphology, or stability. It also increased the microcapsules' resistance to swelling and optimized their mechanical strength. Our findings suggest potential benefits of the bile acid UDCA in β-cell microencapsulation.

An advanced microencapsulated system: a platform for optimized oral delivery of antidiabetic drug-bile acid formulations

INTRODUCTION

In previous studies, we have shown that a gliclazide-cholic acid derivative (G-CA) mixture resulted in an enhanced ileal permeation of G (ex vivo). When administered orally to diabetic rats, it brought about a significant hypoglycaemic effect. In this study, we aim to create a novel microencapsulated-formulation of G-CA with uniform and coherent structure that can be further tested in our rat model of type 1 diabetes (T1D). We also aim to examine the effect of CA addition to G microcapsules in the morphology, structure and excipients' compatibility of the newly designed microcapsules.

METHOD

Microencapsulation was carried out using our Buchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) and G-CA-SA (test) at a constant ratio (1:3:30), respectively. Complete characterizations of microcapsules were carried out.

RESULTS

The new G-CA-SA formulation is further optimized by the addition of CA exhibiting pseudoplastic-thixotropic rheological characteristics. Bead size remains similar after CA addition, the new microcapsules show no chemical interactions between the excipients and this was supported further by the spectral studies suggesting bead stability.

CONCLUSION

The new microencapsulated-formulation has good and uniform structural properties and may be suitable for oral delivery of antidiabetic-bile acid formulations.

Stability and Release Kinetics of an Advanced Gliclazide-Cholic Acid Formulation: The Use of Artificial-Cell Microencapsulation in Slow Release Targeted Oral Delivery of Antidiabetics

Introduction

In previous studies carried out in our laboratory, a bile acid (BA) formulation exerted a hypoglycaemic effect in a rat model of type-1 diabetes (T1D). When the antidiabetic drug gliclazide (G) was added to the bile acid, it augmented the hypoglycaemic effect. In a recent study, we designed a new formulation of gliclazide-cholic acid (G-CA), with good structural properties, excipient compatibility and exhibits pseudoplastic-thixotropic characteristics. The aim of this study is to test the slow release and pH-controlled properties of this new formulation. The aim is also to examine the effect of CA on G release kinetics at various pH values and different temperatures.

Method

Microencapsulation was carried out using our Buchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) and G-CA-SA (test) at a constant ratio (1:3:30), respectively. Microcapsules were examined for efficiency, size, release kinetics, stability and swelling studies at pH 1.5, pH 3, pH 7.4 and pH 7.8 and temperatures of 20 and 30 °C.

Results

The new formulation is further optimised by the addition of CA. CA reduced microcapsule swelling of the microcapsules at pH 7.8 and pH 3 at 30 °C and pH 3 at 20 °C, and, even though microcapsule size remains similar after CA addition, percent G release was enhanced at high pH values (pH 7.4 and pH 7.8, p < 0.01).

Conclusion

The new formulation exhibits colon-targeted delivery and the addition of CA prolonged G release suggesting its suitability for the sustained and targeted delivery of G and CA to the lower intestine.

Diabetes and hypertension increase the placental and transcellular permeation of the lipophilic drug diazepam in pregnant women

Background

Previous studies carried out in our laboratories have demonstrated impaired drug permeation in diabetic animals. In this study the permeation of diazepam (after a single dose of 5 mg/day, administered intramuscularly) will be investigated in diabetic and hypertensive pregnant women.

Methods

A total 75 pregnant women were divided into three groups: group 1 (healthy control, n = 31), group 2 (diabetic, n = 14) and group 3 (hypertensive, n = 30). Two sets of diazepam plasma concentrations were collected and measured (after the administration of the same dose of diazepam), before, during and after delivery. The first set of blood samples was taken from the mother (maternal venous plasma). The second set of samples was taken from the fetus (fetal umbilical venous and arterial plasma). In order to assess the effect of diabetes and hypertension on diazepam placental-permeation, the ratios of fetal to maternal blood concentrations were determined. Differences were considered statistically significant if p ≤ 0.05.

Results

The diabetes and hypertension groups have 2-fold increase in the fetal umbilical-venous concentrations, compared to the maternal venous concentrations. Feto: maternal plasma-concentrations ratios were higher in diabetes (2.01 ± 1.10) and hypertension (2.26 ± 1.23) groups compared with control (1.30 ± 0.48) while, there was no difference in ratios between the diabetes and hypertension groups. Umbilical-cord arterial: venous ratios (within each group) were similar among all groups (control: 0.97 ± 0.32; hypertension: 1.08 ± 0.60 and diabetes: 1.02 ± 0.77).

Conclusions

On line with our previous findings which demonstrate disturbed transcellular trafficking of lipophilic drugs in diabetes, this study shows significant increase in diazepam placental-permeation in diabetic and hypertensive pregnant women suggesting poor transcellular control of drug permeation and flux, and bigger exposure of the fetus to drug-placental transport.

Deoxycholic Acid as a Modifier of the Permeation of Gliclazide through the Blood Brain Barrier of a Rat

Major problem for diabetic patients represents damage of blood vessels and the oxidative stress of the brain cells due to increased concentration of free radicals and poor nutrition of brain cells. Gliclazide has antioxidative properties and poor blood brain barrier (BBB) penetration. Bile acids are known for their hypoglycemic effect and as promoters of drug penetration across biological membranes. Accordingly, the aim of this study is to investigate whether the bile acid (deoxycholic acid) can change the permeation of gliclazide, through the blood brain barrier of a rat model type-1 diabetes. Twenty-four male Wistar rats were randomly allocated to four groups, of which, two were given alloxan intraperitoneally (100 mg/kg) to induce diabetes. One diabetic group and one healthy group were given a bolus gliclazide intra-arterially (20 mg/kg), while the other two groups apart from gliclazide got deoxycholic acid (4 mg/kg) subcutaneously. Blood samples were collected 30, 60, 150, and 240 seconds after dose, brain tissues were immediately excised and blood glucose and gliclazide concentrations were measured. Penetration of gliclazide in groups without deoxycholic acid pretreatment was increased in diabetic animals compared to healthy animals. Also in both, the healthy and diabetic animals, deoxycholic acid increased the permeation of gliclazide through that in BBB.

Probiotics decreased the bioavailability of the bile acid analog, monoketocholic acid, when coadministered with gliclazide, in healthy but not diabetic rats

In recent studies we showed that gliclazide has no hypoglycemic effect on type 1 diabetic (T1D) rats while MKC does, and their combination exerted a better hypoglycemic effect than MKC alone. We also showed that the most hypoglycemic effect was noticed when T1D rats were treated with probiotics then gavaged with MKC + gliclazide (blood glucose decreased from 24 ± 3 to 10 ± 2 mmol/l). The aim of this study is to investigate the influence of probiotics on MKC pharmacokinetics when coadministered with gliclazide, in T1D rats. 80 male Wistar rats (weight 350 ± 50 g) were randomly allocated into 8 groups (10 rats/group), 4 of which were injected with alloxan (30 mg/kg) to induce T1D. Group 1 was healthy and group 2 was diabetic. Groups 3 (healthy) and 4 (diabetic) were gavaged with probiotics (75 mg/kg) every 12 h for 3 days and 12 h later all groups received a single oral dose of MKC + gliclazide (4 and 20 mg/kg respectively). The remaining 4 groups were treated in the same way but administered MKC + gliclazide via the i.v. route. Blood samples collected from T1D rats prior to MKC + gliclazide revealed that probiotic treatment alone reduced blood glucose levels twofold. When coadministered with gliclazide, the bioavailability of MKC was reduced in healthy rats treated with probiotics but remained the same in diabetic pretreated rats. The decrease in MKC bioavailability, when administered with gliclazide, caused by probiotic treatment in healthy but not diabetic rats suggests that probiotic treatment induced MKC metabolism or impaired its absorption, only in healthy animals. The different MKC bioavailability in healthy and diabetic rats could be explained by different induction of presystemic elimination of MKC in the gut by probiotic treatment.

In vitro-in vivo correlation for gliclazide immediate-release tablets based on mechanistic absorption simulation

The aim of this study was to develop a drug-specific absorption model for gliclazide (GLK) using mechanistic gastrointestinal simulation technology (GIST) implemented in GastroPlus(TM) software package. A range of experimentally determined, in silico predicted or literature data were used as input parameters. Experimentally determined pH-solubility profile was used for all simulations. The human jejunum effective permeability (P (eff)) value was estimated on the basis of in vitro measured Caco-2 permeability (literature data). The required PK inputs were taken from the literature. The results of the simulations were compared with actual clinical data and revealed that the GIST-model gave accurate prediction of gliclazide oral absorption. The generated absorption model provided the target in vivo dissolution profile for in vitro-in vivo correlation and identification of biorelevant dissolution specification for GLK immediate-release (IR) tablets. A set of virtual in vitro data was used for correlation purposes. The obtained results suggest that dissolution specification of more than 85% GLK dissolved in 60 min may be considered as "biorelevant" dissolution acceptance criteria for GLK IR tablets.