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

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

Flow vibration-doubled concentric system coupled with low ratio amine to produce bile acid-macrocapsules of ß-cells

© 2016 Future Science Ltd. Background: Pancreatic ß-cell microencapsulation using sodium alginate (SA), polylornithine (PLO) copolymers, and ultrasoluble hydrogels, polystyrenes and polyallamines (PAA), has been heavily studied. However, long-term success remains limited due to poor macrocapsules' physical properties and cell functions. Our study aimed to incorporate percentages of PAA and ursodeoxycholic acid, into SA and PLO dispersion mixture and examine best microencapsulating methods and best macrocapsules containing ß-cells. Methods/results: Microencapsulating parameters were examined and the Flow-Vibrational Nozzle built-in system was screened and found to be most efficient at high frequency (1900 Hz). Macrocapsules were produced with or without ursodeoxycholic acid in percentages: 0.018SA:0.01PLO:0.005PAA:0.04ursodeoxycholic acid (up to 100% H2O). Using the refined microencapsulation method with vibrational frequency of 1900 Hz, macrocapsules with ursodeoxycholic acid had optimized cell viability and biological functions and ameliorated inflammatory biomarkers. Conclusion: High frequency and air-pressure with Flow-Vibrational encapsulation using the mixture: 0.018SA:0.01PLO:0.005PAA:0.04ursodeoxycholic acid resulted in better cell biology suggesting potentials in ß-cell transplantation

Biological Assessments of Encapsulated Pancreatic ß-Cells: Their Potential Transplantation in Diabetes

© 2016. Biomedical Engineering Society. Microencapsulation of pancreatic islets has been considered as a promising method for cell transplantation and diabetes treatment. However, in vivo trials to date have been hampered by fibrotic overgrowth and very limited to no success, long-term. Future success requires suitable microencapsulating method and possibly a simplified and suitable formulation which will produce a microcapsule that provides an immunobarrier, maintain full ß-cell functionality whilst also reducing the inflammatory processes that induce fibrosis. In multiple studies, we screened various formulations and microencapsulating methods, and obtained promising results using bile acid-based microcapsules containing ß-cells, in terms of cell functions and insulin release. Thus, this study aimed to refine further the microencapsulating method using a simple alginate-poly-l-ornithine formulation and test the effect of adding a promising bile acid, ursodeoxycholic acid (UDCA), on cell functions. Using Büchi concentric nozzle, viable NIT-1 cells were microencapsulated using alginate-poly-l-ornithine, with or without UDCA at a ratio of 1:1.2 or 1:1.2:4. Screening for nozzle temperature and nozzle-gelation bath distance was carried out to form best microcapsules. Microcapsules were cultured for 48 h and examined for size and surface morphology, chemical profiling and ß-cell viability. Culture supernatants were examined for insulin and inflammatory cytokines. When using 30 °C nozzle-temperature and 5 cm nozzle-gelation bath distance, in the presence of the bile acid, cell mitochondrial activities and insulin production were optimised. Under deployed microencapsulating method with nozzle-temperature of 30 °C and nozzle-gelation bath distance of 5 cm, the incorporation of the bile acid into the microcapsules resulted in enhanced ß-cell survival, function and improved overall biocompatibility supporting potential applications in transplantation

Influence of Biotechnological Processes, Speed of Formulation Flow and Cellular Concurrent Stream-Integration on Insulin Production from ß-cells as a Result of Co-Encapsulation with a Highly Lipophilic Bile Acid

Introduction: We have shown that incorporation of the hydrophilic bile acid, ursodeoxycholic acid, into ß-cell microcapsules exerted positive effects on microcapsules’ morphology and size, but these effects were excipient and method dependent. Cell viability remained low which suggests low octane-water solubility and formation of highly hydrophilic dispersion, which resulted in low lipophilicity dispersion and compromised cellular permeation of the incorporated bile acid. Thus, this study aimed at investigating various microencapsulating methodologies using highly lipophilic bile acid (LPBA), in order to optimise viability and functions of microencapsulated ß-cells. Methods: Four different types of microcapsules were produced with (test) and without (control) LPBA, totalling eight different microcapsules. Microencapsulating methodologies were screened for best microcapsule-cell functions and microencapsulating processes were examined in terms of frequency, formulation flow, total bath-gelation time and cellular concurrent stream-integration rate, cell-viability, insulin production and inflammatory profile. Results: Optimum biotechnological processes include formation frequency (Hz) of 2350, formulation flow (ml/min) of 1.2, total gelation time (min) of 18 and cellular concurrent stream-integration rate (ml/min) of 0.7. In all formulations, LPBA consistently improved cell viability, insulin production, mitochondrial activities and ameliorated inflammation. Conclusion: The deployed biotechnological processes and LPBA optimised formation and functions of ß-cell microcapsules, which suggests potential applications in diabetes mellitus via the creation of more stable ß-cell microcapsules capable of delivering adequate levels of insulin to control glycaemia and potentially curing diabetes

Eudragit®-based microcapsules of probucol with a gut-bacterial processed secondary bile acid

© 2018 Newlands Press. Aim: Deoxycholic acid (DCA) has improved gliclazide oral absorption, while Eudragit® (ED) polymers have improved formulation stability of antidiabetic drugs. The aim of the study is to test if DCA and ED encapsulation will optimize the release and stability of the potential antidiabetic drug probucol (PB). Materials & methods: The PB formulations were prepared using ED polymers and DCA, and formulations were analyzed for their rheological and biological properties. Results: Rheological properties and size distribution were similar among all groups. ß-cell survival and biological activities were best with NM30D microcapsules. The inflammatory profile and oxidative stress effects of microcapsules remained similar among all groups. Conclusion: ED NM30D and DCA incorporation can exert positive and stabilizing effects on PB oral microcapsules

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 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-a, IFN-?, IL-1ß, 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

Alginate-deoxycholic Acid Interaction and Its Impact on Pancreatic ?-Cells and Insulin Secretion and Potential Treatment of Type 1 Diabetes

© 2016. Springer Science+Business Media New York.Introduction: The secondary bile acid, deoxycholic acid (DCA), has been shown to exert membrane stabilising effects on a pH sensitive delivery system for the oral delivery of insulin. However, its potential applications in the microencapsulation of pancreatic ß-cells using hydrogels and polyelectrolytes have not been investigated and may require refined microencapsulating methods. Thus, this study aimed to optimise a newly developed microencapsulating method for pancreatic ß-cell delivery (Ionic-Gelation-Vibrational-Jet-Flow; IGVJF) and examine the effects of DCA incorporation on ß-cells microcapsules, using various excipients. Methods: Ten different formulations were prepared (five controls and five tests containing DCA) utilising different concentrations of water soluble gel, polystyrenes, sodium alginate (SA), polyallylamine, and poly-L-ornithine (PLO), and different microencapsulating methods were screened for most uniform microcapsules. The net flow nozzle size ratio of inner:outer flow through the concentric system was examined for best microcapsules. ß-cell microcapsules for each formulation were analysed for cell biology and functions (insulin at 1 and 60 h), and microcapsules were examined for appearance. Results: The used IGVJF method produced best microcapsules when the inner:outer flow nozzle size is 120/200 µm. In addition, deoxycholic acid addition produced higher cell biological activity and functions, postmicroencapsulation, regardless of excipients’ ratio used. DCA has inhibitory effects on pro-inflammatory cytokine secretion by the microencapsulated cells, while microcapsule size and strength remained similar. Microcapsule morphology and membrane surface characteristics were similar for all formulations with noticeable improvements by DCA addition occurring at the lowest PLO concentrations. Conclusion: An inner:outer nozzle size of 120/200 µm, in the deployed microencapsulating method, in combination with the secondary bile acid deoxycholic acid, produced stable microcapsules with improved cell functionality, suggesting suitability for cell microencapsulation and transplantation