Improved bioavailability of orally delivered insulin using Eudragit-L30D coated PLGA microparticles

Large porous microparticles of PLGA entrapping insulin were prepared by solvent evaporation method and evaluated in diabetes induced rat for its efficacy in maintaining blood sugar level from a single oral dose. Incorporation of Eudragit L30D (0.03% w/v) in the external aqueous phase resulted in formation of pH responsive enteric coated polymer particles which release most of the entrapped insulin in alkaline pH. At acidic pH, release of insulin from uncoated PLGA microparticles and Eudragit L30D coated PLGA microparticles was 31.62?±?1.8% and 17.5?±?1.29%, respectively, for initial 30 min. However, in 24 h, in vitro released insulin from uncoated PLGA and Eudragit coated particles was 96.29?±?1.01% and 88.30?±?1%, respectively. Released insulin from composite polymer particles were mostly in monomer form without aggregation and was stable for a month at 37°C. Oral administration of insulin loaded PLGA (50 : 50) and Eudragit L30D coated PLGA (50 : 50) microparticles (equivalent to 25 IU insulin/kg of animal weight) in alloxan induced diabetic rats resulted in 37.3?±?11% and 62.7?±?3.8% reduction in blood glucose level, respectively, in 2 h. This effect continued up to 24 h in the case of Eudragit L30D coated PLGA microparticles. Results demonstrate that use of stabilizers during PLGA particle formulation, large porous particle for quick release of insulin and coating with Eudragit L30D resulted in a novel oral formulation for once a day delivery of insulin.     

Improved bioavailability of orally delivered insulin using Eudragit-L30D coated PLGA microparticles

Large porous microparticles of PLGA entrapping insulin were prepared by solvent evaporation method and evaluated in diabetes induced rat for its efficacy in maintaining blood sugar level from a single oral dose. Incorporation of Eudragit L30D (0.03% w/v) in the external aqueous phase resulted in formation of pH responsive enteric coated polymer particles which release most of the entrapped insulin in alkaline pH. At acidic pH, release of insulin from uncoated PLGA microparticles and Eudragit L30D coated PLGA microparticles was 31.62 +/- 1.8% and 17.5 +/- 1.29%, respectively, for initial 30 min. However, in 24 h, in vitro released insulin from uncoated PLGA and Eudragit coated particles was 96.29 +/- 1.01% and 88.30 +/- 1%, respectively. Released insulin from composite polymer particles were mostly in monomer form without aggregation and was stable for a month at 37 degrees C. Oral administration of insulin loaded PLGA (50 : 50) and Eudragit L30D coated PLGA (50 : 50) microparticles (equivalent to 25 IU insulin/kg of animal weight) in alloxan induced diabetic rats resulted in 37.3 +/- 11% and 62.7 +/- 3.8% reduction in blood glucose level, respectively, in 2 h. This effect continued up to 24 h in the case of Eudragit L30D coated PLGA microparticles. Results demonstrate that use of stabilizers during PLGA particle formulation, large porous particle for quick release of insulin and coating with Eudragit L30D resulted in a novel oral formulation for once a day delivery of insulin.     

Encapsulation of poorly soluble basic drugs into enteric microparticles: a novel approach to enhance their oral bioavailability

Poorly water soluble basic drugs are very sensitive to pH changes and following dissolution in the acidic stomach environment tend to precipitate upon gastric emptying, which leads to compromised or erratic oral bioavailability. In this work, we show that the oral bioavailability of a model poorly soluble basic drug (cinnarizine) can be improved by drug encapsulation within highly pH-responsive microparticles (Eudragit L). The latter was prepared by emulsion solvent evaporation which yielded discrete spherical microparticles (diameter of 56.4 ± 6.8 μm and a span of 1.2 ± 0.3). These Eudragit L (dissolution threshold pH 6.0) microparticles are expected to dissolve and release their drug load at intestinal conditions. Thus, the enteric microparticles inhibited the in vitro release of drug under gastric conditions, despite high cinnarizine solubility in the acidic medium. At intestinal conditions, the particles dissolved rapidly and released the drug which precipitated out in the dissolution vessel. In contrast, cinnarizine powder showed rapid drug dissolution at low pH, followed by precipitation upon pH change. Oral dosing in rats resulted in a greater than double bioavailability of Eudragit L microparticles compared to the drug powder suspension, although C_max and T_max were similar. The higher bioavailability with microparticles contradicts the in vitro results. Such an example highlights that although in vitro results are an indispensable tool for formulation development, an early in vivo assessment of formulation behaviour can provide better prediction for oral bioavailability.     

Evaluation of Eudragit-coated chitosan microparticles as an oral immune delivery system

Chitosan microparticles containing ovalbumin (OVA), OVA-containing chitosan microparticles (Chi-OVA), were prepared, coated with Eudragit L100 (ER), and evaluated as oral vaccine. Chi-OVA with an OVA content of 34.4% (w/w) and a mean particle size of 2.3 microm were used for experiments in vitro and in vivo. ER-coated Chi-OVA (ER-Chi-OVA) contained 3.6-20.5% (w/w) OVA and had a particle size of 47.9-161.1 microm. Chi-OVA dissolved readily in JP 14 first fluid, but not in JP 14 second fluid. The release of OVA from Chi-OVA was suppressed extensively in JP 14 second fluid. ER-Chi-OVA did not dissolve in JP 14 first fluid, and the release of OVA was suppressed greatly in JP 14 first and second fluids. OVA solution, Chi-OVA and ER-Chi-OVA (200 and 800 microg OVA/mouse) were administered to Balb/C mice twice at a 1-week interval. At 7 d after the second administration, plasma OVA-specific IgG and fecal OVA-specific IgA levels were measured. OVA-specific IgG tended to be enhanced in Chi-OVA and ER-Chi-OVA, but was the highest in OVA solution. OVA-specific IgA was induced significantly more efficiently by ER-Chi-OVA than the others. These suggested that ER-Chi-OVA should be possibly useful to induce an intestinal mucosal immune response.     

Nanostructured porous silicon microparticles enable sustained peptide (Melanotan II) delivery

Peptide molecules can improve the treatment of a number of pathological conditions, but due to their physicochemical properties, their delivery is very challenging. The study aim was to determine whether nanostructured porous silicon could sustain the release and prolong the duration of action of a model peptide Melanotan II (MTII). Thermally hydrocarbonized nanoporous silicon (THCPSi) microparticles (38-53 μm) were loaded with MTII. The pore diameter, volume, specific surface area and loading degree of the microparticles were analyzed, and the peptide release was evaluated in vitro. The effects of MTII on heart rate and water consumption were investigated in vivo after subcutaneous administration of the MTII loaded microparticles. A peptide loading degree of 15% w/w was obtained. In vitro studies (PBS, pH 7.4, 37 °C) indicated sustained release of MTII from the THCPSi microparticles. In vivo, MTII loaded THCPSi induced an increase in the heart rate 2 h later than MTII solution, and the effect lasted 1 h longer. In addition, MTII loaded THCPSi changed the water consumption after 150 min, when the immediate effect of MTII solution was already diminished. The present study demonstrates that MTII loading into nanosized PSi pore structure enables sustained delivery of an active peptide.     

A novel pH-sensitive interferon-β (INF-β) oral delivery system for application in multiple sclerosis

pH-sensitive microparticles were prepared using trimethyl-chitosan (TMC), poly(ethylene glycol)dimethacrylate (PEGDMA) and methacrylic acid (MAA) by free radical suspension polymerization, for the oral delivery of interferon-β (INF-β). The microparticles were subsequently compressed into a suitable oral tablet formulation. A Box–Behnken experimental design was employed for generating a series of formulations with varying concentrations of TMC (0.05–0.5 g/100 mL) and percentage crosslinker (polyethylene glycol diacrylate) (3–8%, w/w of monomers), for establishment of an optimized TMC-PEGDMA-MAA copolymeric microparticles. For pragmatism, insulin was initially employed as the model peptide for undertaking the preliminary experimentation and the optimized formulation was subsequently evaluated using INF-β. The prepared copolymeric microparticulate system was characterized for its morphological, porositometric and mucoadhesive properties. The optimized microparticles with 0.5 g/100 mL TMC and 3% crosslinker had an INF-β loading efficiency of 53.25%. The in vitro release of INF-β was recorded at 74% and 3% in intestinal (pH 6.8) and gastric (pH 1.2) pH from the oral tablet formulation, respectively. The tablet was further evaluated for plasma concentration of INF-β in the New Zealand White rabbit, and compared to a known subcutaneous formulation. The system showed an astounding effective release profile over 24 h with higher INF-β plasma concentrations compared with the subcutaneous injection formulation.     

Effects of AF3442 [N-(9-ethyl-9H-carbazol-3-yl)-2-(trifluoromethyl)benzamide], a novel inhibitor of human microsomal prostaglandin E synthase-1, on prostanoid biosynthesis in human monocytes in vitro

Inhibitors of microsomal prostaglandin (PG) E synthase-1 (mPGES-1) are being developed for the relief of pain. Redirection of the PGH₂ substrate to other PG synthases, found both in vitro and in vivo, in mPGES-1 knockout mice, may influence their efficacy and safety. We characterized the contribution of mPGES-1 to PGH₂ metabolism in lipopolysaccharide (LPS)-stimulated isolated human monocytes and whole blood by studying the synthesis of prostanoids [PGE₂, thromboxane (TX)B₂, PGF_2α and 6-keto-PGF_1α] and expression of cyclooxygenase (COX)-isozymes and down-stream synthases in the presence of pharmacological inhibition by the novel mPGES-1 inhibitor AF3442 [N-(9-ethyl-9H-carbazol-3-yl)-2-(trifluoromethyl)benzamide]. AF3442 caused a concentration-dependent inhibition of PGE₂ in human recombinant mPGES-1 with an IC₅₀ of 0.06 μM. In LPS-stimulated monocytes, AF3442 caused a concentration-dependent reduction of PGE₂ biosynthesis with an IC₅₀ of 0.41 μM. At 1 μM, AF3442 caused maximal selective inhibitory effect of PGE₂ biosynthesis by 61 ± 3.3% (mean ± SEM, P < 0.01 versus DMSO vehicle) without significantly affecting other prostanoids (i.e. TXB₂, PGF_2α and 6-keto-PGF_1α). In LPS-stimulated whole blood, AF3442 inhibited in a concentration-dependent fashion inducible PGE₂ biosynthesis with an IC₅₀ of 29 μM. A statistically significant inhibition of mPGES-1 activity was detected at 10 and 100 μM (38 ± 14%, P < 0.05, and 69 ± 5%, P < 0.01, respectively). Up to 100 μM, the other prostanoids were not significantly affected. In conclusion, AF3442 is a selective mPGES-1 inhibitor which reduced monocyte PGE₂ generation also in the presence of plasma proteins. Pharmacological inhibition of mPGES-1 did not translate into redirection of PGH₂ metabolism towards other terminal PG synthases in monocytes. The functional relevance of this observation deserves to be investigated in vivo.     

Chitosan/Kollicoat SR 30D film-coated pellets of aminosalicylates for colonic drug delivery

The purpose of the study was to (i) prepare the chitosan/Kollicoat SR 30D film-coated pellets for colonic drug delivery, and (ii) evaluate the colonic delivery and efficacy of these coated pellets in the rat. The pellets were coated to different film thickness with chitosan/Kollicoat SR 30D formulations. In vitro drug release was assessed in simulated gastrointestinal (GI) tract conditions. Biodistribution of aminosalicylates (5-ASA) in GI tract and plasma was measured after oral administration of coated or uncoated 5-ASA pellets. Efficacy of the coated or uncoated 5-ASA pellets was tested in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rat colitis model. Healing of induced colitis was assessed by measuring the myeloperoxidase activities, colon wet weight/body weight, and damage score. The coating was susceptible to bacteria digestion, resulting in an increase in the release of 5-ASA from the coated pellets. After administration of the coated pellets, the drug concentration in the large intestine was higher than those of uncoated pellets. In plasma, the observed mean C_max from the coated pellets was significantly lower than that of the uncoated pellets. Chitosan/Kollicoat SR 30D film-coated pellets could deliver the 5-ASA to the targeted site, providing effective treatment for inflammatory bowel disease. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:186–195, 2010     

Role of N-methyl-D-aspartate receptors in polychlorinated biphenyl mediated neurotoxicity

Polychlorinated biphenyls (PCBs) are widespread persistent environmental pollutants. Chronic human and animal exposure to PCBs results in various harmful effects including neurotoxicity. This study investigates the effects of the PCB mixture Aroclor 1254 (A1254) and two PCB congeners (coplanar, non-ortho PCB 126, and non coplanar PCB 99) on the expression of N-methyl-D-aspartate receptors (NMDARs) and the subsequent toxic effects using a human SHS5-SY neuroblastoma cell line. NMDAR was measured using a radiolabeled phencyclidine receptor ligand [³H]-MK801, apoptosis was quantified using fluorogenic substrates specific for caspase-3 (DEVD-AFC) and cell death using lactate dehydrogenase (LDH) release. After treatment, a positive dose–response relationship of increasing NMDARS, increasing caspase-3 activity and cell death was observed in all PCB compounds. The non-coplanar PCB compounds were found to be significantly more toxic than the coplanar congener and the PCB mixture A1254. PCB-mediated cell death was attenuated with 10 μM NMDAR antagonists: 1-amino-3,5-dimethyladamantane hydrochloride (memantine) and (+)-5-methyl-10,11-dihydro-5H-debenzocyclhepten-5,10-imine maleate ((+)-MK-801), thus demonstrating the importance of NMDAR in PCB neurotoxicity. Intracellular calcium [Ca²⁺]_i chelator BAPTA-AM (1 μM) partially attenuated the neurotoxic effect of the PCBs suggesting a role of calcium homeostasis disruption in the neurotoxicity of PCBs. These results suggest that the neurotoxicity of PCBs can be mediated through activation of NMDARs.     

Toxicokinetics of acrylamide in rats and humans following single oral administration of low doses

The rodent carcinogen acrylamide (AA) is formed during preparation of starch-containing foods. AA is partly metabolized to the genotoxic epoxide glycidamide (GA). After metabolic processing, the mercapturic acids N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA), rac-N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA) and rac-N-acetyl-S-(1-carbamoyl-moyl-2-hydroxyethyl)-L-cysteine (iso-GAMA) are excreted with urine. In humans, AAMA can be sulfoxidized to AAMA-sulfoxide. The aim of this study was to assess potential species-differences in AA-toxicokinetics in rats and humans after single oral administration of doses similar to the daily human dietary exposure. Male Fischer 344 rats (n = 5/dose group) were administered 20 and 100 μg/kg b.w. ¹³C₃-AA in deionized water via oral gavage. Human subjects (n = 3/gender) were orally administered 0.5 and 20 μg/kg b.w. ¹³C₃-AA with drinking water. Urine samples were collected in intervals for 96 and 94 h, respectively. Urinary concentrations of ¹³C₃-AAMA, ¹³C₃-GAMA and ¹³C₃-AAMA-sulfoxide were monitored by liquid chromatography-tandem mass spectrometry. The recovered urinary metabolites accounted for 66.3% and 70.5% of the 20 and 100 μg/kg b.w. doses in rats and for 71.3% and 70.0% of the 0.5 and 20 μg/kg b.w. doses in humans. In rats, ¹³C₃-AAMA accounted for 33.6% and 38.8% of dose and 32.7% and 31.7% of dose was recovered as ¹³C₃-GAMA; ¹³C₃-AAMA-sulfoxide was not detected in rat urine. In humans, ¹³C₃-AAMA, ¹³C₃-GAMA and ¹³C₃-AAMA-sulfoxide accounted for 51.7% and 49.2%, 6.3% and 6.4% and 13.2% and 14.5% of the applied dose, respectively. The obtained results suggest that the extent of AA bioactivation to GA in humans is lower than in rodents.     

Biodegradable multiblock poly(N-2-hydroxypropyl)methacrylamide gemcitabine and paclitaxel conjugates for ovarian cancer cell combination treatment

The synthesis, characterization, and in vitro evaluation of a combination delivery of multiblock poly(N-2-hydroxypropyl)methacrylamide (HPMA), gemcitabine (GEM) and paclitaxel (PTX) conjugates is described in this study. Multiblock copolymer conjugates of a large molecular weight (M_w > 200 kDa) were studied and compared to traditional, small molecular weight (M_w < 45 kDa) conjugates. Stability of the conjugates in different pH was assessed, and their cytotoxicity in combination toward A2780 human ovarian cancer cells was evaluated by combination index analysis. Treatment duration (4 and 72 h) and sequence of addition were explored. In addition, an HPMA copolymer conjugate with both GEM and PTX in the side chains was evaluated in a similar manner and compared to a physical mixture of individual conjugates. Conjugates with narrow molecular weight distribution (M_w/M_n < 1.1) were obtained via RAFT polymerization, and drug loadings of between 5.5 and 9.2 wt% were achieved. Conjugates demonstrated moderate stability with less than 65% release over 24 h at pH 7.4, and near complete drug release in the presence of the lysosomal enzyme cathepsin B in 3 h. In combination, the cytotoxic effects of a mixture of the conjugates were primarily additive. Synergistic effects were observed when A2780 human ovarian cancer cells were treated simultaneously for 4 h with multiblock conjugates (CI < 0.7). When both GEM and PTX were conjugated to the same copolymer backbone, moderate antagonism (CI 1.3–1.6) was observed. These results demonstrate that multiblock HPMA copolymer–GEM and –PTX conjugates, when delivered as a mixture of individual agents, are promising for the treatment of ovarian cancer.     

Preparation and evaluation of double-walled microparticles prepared with a modified water-in-oil-in-oil-in-water (w1/o/o/w3) method

Abstract

In this study, a modified water-in-oil-in-oil-in-water (w₁/o/o/w₃) method was developed to prepare double-walled microparticles containing ovalbumin (OVA). The microparticles were characterized with respect to their morphology, particle size, encapsulation efficiency, production yield, thermal properties and in vitro drug release. Microscopy observations clearly showed that microparticles have spherical shape and smooth surface. These microparticles were characterized to have double-walled structure, with a cavity in the centre. By using w₁/o/o/w₃ method, a significant decrease in mean particle size and a significant increase in encapsulation efficiency were obtained. The mean particle size and the encapsulation efficiency of double-walled microparticles were also affected by the changing amount of OVA and mass ratio of polymers. Microparticles prepared with two polymers exhibited a significantly lower initial burst release followed by sustained release compared to microparticles made from poly(d,l-lactide-co-glycolide) 50/50 only. It can be concluded that these microparticles can be a potential delivery system for therapeutic proteins.     

An approach to a cold chain free oral cholera vaccine: in vitro and in vivo characterization of Vibrio cholerae gastro-resistant microparticles

The present work describes the formulation of Eudragit^® L30 D-55 microparticles (MP) alone or with mucoadhesive agents, alginate or Carbopol^®, as an approach for the development of an oral cholera vaccine. In the first part, a spray drying technique was optimized for microparticle elaboration, obtaining a microparticle size ranging from 7 to 9 μm with high encapsulation efficiencies. Moreover, gastro resistant properties and Vibrio cholerae (VC) antigenicity were maintained, but for Eudragit^®-Carbopol^® microparticles which showed low antigenicity values, ≈25%. Next, a stability study was performed following ICH Q1 A (R2) guidelines, i.e. 25 °C-60% relative humidity (RH) for 12 months, and 30 °C-65% RH and 40 °C-75% RH for 6 months. Upon storage, microparticle size changed slightly, 1 μm for Eudragit^®-alginate MPs and 0.36 μm for Eudragit^®MP. However, gastro resistance and antigenicity values were kept in an acceptance range. In the third stage of this work, in vivo experiments were performed. The immune response evoked was measured by means of vibriocidal titer quantification, observing that Eudragit^®-alginate MPs were able to induce stronger immune responses, comparable to the free VC. Therefore, microencapsulation of VC by spray drying could be proposed as an approach to a cold chain free and effective oral cholera vaccine.     

Composite microparticles with in vivo reduction of the burst release effect

The aim of this study was to develop microparticles containing nanoparticles (composite microparticles) for prolonged drug delivery with reduced burst effect in vitro and in vivo. Such composite microparticles were prepared with hydrophobic and biodegradable polymers [poly(ε-caprolactone), poly(lactic-co-glycolic) acid]. Ibuprofen was chosen as the model drug, and microparticles were prepared by the extraction technique with ethyl acetate as the solvent. Nanoparticles and microparticles and an ibuprofen solution (Pedea^®) were administered subcutaneously at the dose of 1 mg of ibuprofen per kg to overnight-fasted rats (male Wistar). Composite microparticles showed prolonged ibuprofen release and less burst effect when compared to simple microparticles (without nanoparticles inside) or nanoparticles both in vitro (PBS buffer) and in vivo. Moreover, ibuprofen was still detected in the plasma after 96 h with composite microparticles. Consequently, it has been demonstrated that composite microparticles were able to reduce burst release and prolong the release of ibuprofen for a long period of time.     

Dexamethasone-containing biodegradable superparamagnetic microparticles for intra-articular administration: Physicochemical and magnetic properties, in vitro and in vivo drug release

Compared with traditional drug solutions or suspensions, polymeric microparticles represent a valuable means to achieve controlled and prolonged drug delivery into joints, but still suffer from the drawback of limited retention duration in the articular cavity. In this study, our aim was to prepare and characterize magnetic biodegradable microparticles containing dexamethasone acetate (DXM) for intra-articular administration. The superparamagnetic properties, which result from the encapsulation of superparamagnetic iron oxide nanoparticles (SPIONs), allow for microparticle retention with an external magnetic field, thus possibly reducing their clearance from the joint. Two molecular weights of poly(lactic-co-glycolic acid) (PLGA) were used, 12 and 19 kDa. The prepared batches were similar in size (around 10 μm), inner morphology, surface morphology, charge (neutral) and superparamagnetic behaviour. The SPION distribution in the microparticles assessed by TEM indicates a homogeneous distribution and the absence of aggregation, an important factor for preserving superparamagnetic properties. DXM release profiles were shown to be quite similar in vitro (ca. 6 days) and in vivo, using a mouse dorsal air pouch model (ca. 5 days).     

Coated whey protein/alginate microparticles as oral controlled delivery systems for probiotic yeast

Viable Saccharomyces boulardii, used as a biotherapeutic agent, was encapsulated in food-grade whey protein isolate (WP) and alginate (ALG) microparticles, in order to protect and vehicle them in gastrointestinal environment. Yeast-loaded microparticles with a WP/ALG ratio of 62/38 were produced with high encapsulation efficiency (95%) using an extrusion/cold gelation method and coated with ALG or WP by a simple immersion method. Swelling, yeast survival, WP loss and yeast release in simulated gastric and intestinal fluids (SGF and SIF, pH 1.2 and 7.5) with and without their respective digestive enzymes (pepsin and pancreatin) were investigated. In SGF, ALG network shrinkage limited enzyme diffusion into the WP/ALG matrix. Coated and uncoated WP/ALG microparticles were resistant in SGF even with pepsin. Survival of yeast cells in microparticles was 40% compared to 10% for free yeast cells and was improved to 60% by coating. In SIF, yeast cell release followed coated microparticle swelling with a desirable delay. Coated WP/ALG microparticles appear to have potential as oral delivery systems for Saccharomyces boulardii or as encapsulation means for probiotic cells in pharmaceutical or food processing applications.     

Monascus-fermented metabolite monascin suppresses inflammation via PPAR-γ regulation and JNK inactivation in THP-1 monocytes

Fermentation products of the fungus Monascus offer valuable therapeutic benefits and have been used extensively for centuries in Asia. The aim of this study is to investigate the inhibitory effect of the Monascus-fermented metabolite monascin (MS) on the molecular mechanism of ovalbumin (OVA)-induced inflammation in the human THP-1 monocyte cell line. We found that 1, 5, and 25 μM of MS significantly attenuated several proinflammatory mediators, including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression as well as nitric oxide (NO) and prostaglandin E₂ (PGE₂) formation caused by OVA stimulation. Further, 5 and 25 μM of MS significantly reduced the generation of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) at both the protein and mRNA levels. MS (5 and 25 μM) decreased OVA-induced phosphorylation of mitogen-activated protein kinase (MAPK) c-Jun NH₂-terminal kinase (JNK), but not that of extracellular signal-regulated kinase (ERK) or p38 kinase. We used the peroxisome proliferator activated receptor-γ (PPAR-γ) antagonist GW9662 to show that MS inhibit JNK phosphorylation through increased expression of PPAR-γ. Thus, the metabolites from Monascus fermentation may serve as a dietary source of anti-inflammatory agents.     

Investigations on the cytochrome P450 (CYP) isoenzymes involved in the metabolism of the designer drugs N-(1-phenyl cyclohexyl)-2-ethoxyethanamine and N-(1-phenylcyclohexyl)-2-methoxyethanamine

Investigations using insect cell microsomes with cDNA-expressed human cytochrome P450 (CYP)s and human liver microsomes (HLM) are reported on the CYP isoenzymes involved in the metabolism of the designer drugs N-(1-phenylcyclohexyl)-2-ethoxyethanamine (PCEEA) to O-deethyl PCEEA and N-(1-phenylcyclohexyl)-2-methoxyethanamine (PCMEA) to O-demethyl PCMEA. Gas chromatography-mass spectrometry or liquid chromatography-mass spectrometry was used for the analysis of the incubation samples. PCEEA O-deethylation was catalyzed by CYP2B6, CYP2C9, CYP2C19, and CYP3A4, while PCMEA O-demethylation was catalyzed only by CYP2B6 and CYP2C19. Considering the relative activity factor approach, these enzymes accounted for 53%, 25%, 4%, and 18% of net clearance for PCEEA and 91% and 9% of net clearance for PCMEA, respectively. The chemical CYP2B6 inhibitor 4-(4-chlorobenzyl)pyridine (CBP) reduced the metabolite formation in pooled HLM by 63% at 1 μM PCEEA. At 10 μM PCEEA, CBP reduced metabolite formation by 61%, while inhibition of CYP3A4 by ketoconazole and inhibition of CYP2C9 by sulfaphenazole showed no inhibitory effect. At 1 μM PCMEA, CBP reduced metabolite formation in pooled HLM by 70% and at 10 μM PCMEA by 78%, respectively. In conclusion, the main metabolic step of both studied drugs was catalyzed by different CYPs.     

Preparation,characterization, and evaluation in vivo of Ins-SiO2-HP55 (insulin-loaded silica coating HP55) for oral delivery of insulin

Insulin is the most effective and durable drug in the treatment of advanced stage diabetes. However, oral delivering insulin was a tough task for rapid enzymatic degradation. In this work, we designed and developed a delivery system composed of enteric nanosphere for oral delivery of insulin. The silica was selected for loading insulin, which surface has a lot of pores with a powerful adsorption capacity, advantages for permeability and slow-release. The insulin-loaded silica (Ins-SiO₂) was prepared by adsorption in HCl solution. The Ins-SiO₂ obtained was coated with the hydroxypropyl methylcellulose phthalate (HP55) by desolvation method, which is a good enteric coating material. The Ins-SiO₂-HP55, an enteric nanosphere of insulin obtained were characterized by transmission electron microscope (TEM), surface area, Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that insulin was loaded most in the pores of silica, while the HP55 coated on the extent of Ins-SiO_2. In vitro drug release results revealed that the release of insulin from Ins-SiO₂-HP55 was markedly reduced in simulated gastric fluid (SGF). By contrast, the release amount of insulin from Ins-SiO₂-HP55 was increased significantly in simulated intestinal fluid (SIF). In vivo evaluation on diabetic animals showed the blood glucose level of diabetic rats could be effectively reduced after oral administration Ins-SiO₂-HP55. There is marked hypoglycemic effect after 1 h of taking the Ins-SiO₂-HP55. After 3 h, the GLU of rats of the Ins-SiO₂-HP55 stably kept from 4.85 to 2.67 mmol/L that was significantly less than the normal level (6.7 mmol/L). However, that of rats taking raw insulin kept from 8.03 to 6.56 mmol/L that is higher than the normal level. These results suggested that Ins-SiO₂-HP55 could have potential value in oral administration systems of diabetes chemotherapy.     

A Multi‐mechanistic Drug Release Approach in a Bead Dosage Form and In Vivo Predictions

Our previous study has successfully prepared a combination of immediate release, enteric coated, and controlled release (CR) beads and mathematically modeled in vitro drug release characteristics of the combination based on the release profiles of individual beads. The objectives of the present study are to evaluate the combination and individual beads in vivo and to mathematically model in vivo drug input characteristics of the combination based on the in vivo input of individual beads. Beagle dogs were used as an animal model, and theophylline as a model drug. In vivo percent drug absorbed at different times (input function) after administration of a capsule bead dosage form was calculated using the Wagner–Nelson deconvolution method using intravenous injection of theophylline in each dog as a reference. The in vivo input functions of individual beads were each fitted to appropriate mathematical equations. The in vivo input function of the bead combination dosage form was calculated based on the individual mathematical equations (expected), and verified experimentally in vivo (experimental). The results showed that all bead dosage forms behave in vivo as defined in vitro. Enteric coated beads significantly delay the time to reach the maximum concentration of drug (t_max = 4.9h) compared to uncoated immediate release beads (2h). The lag time of enteric coated beads is 1.1h. CR beads showed both longer t_max (6h) and mean residence time (MRT = 9.7h) compared to the uncoated immediate release beads (t_max = 2h and MRT = 7.1h) as designed in vitro. The in vivo input functions for the three individual beads can be fitted to equations as a function of square root of time. The combined bead dosage form showed t_max of 2.4h and MRT of 7.9h. The experimental and expected in vivo input profiles agreed to within ± 12% (residues at individual data points). Our results suggest that the drug input function of a combined multi‐mechanism oral dosage form can be predicted from the in vivo performance of individual formulations using the dog as an in vivo model.