Development of a new esomeprazole delayed release gastro-resistant pellet formulation with improved storage stability.

This study describes the development of a new esomeprazole (ESO) delayed release gastro-resistant formulation with improved storage stability. A three-step (drug-, sub(seal)- and enteric-) coating process was employed with the aid of a fluid bed coater. Several formulation factors (namely, size and quantity of starting non-pareil sugar spheres, binder quantity during drug-layering, sub(seal)-coating polymer type, and quantity and enteric coating quantity) were evaluated and the whole process was modeled with the aid of feed-forward back-propagation artificial neural networks (ANNs). Results showed that the selection of small-sized starting spheres (45/60 mesh size) leads to pellet agglomeration, while as sub(seal)-coating weight gain increases a reduction in ESO dissolution rate is observed. The enteric-coating applied (Eudragit L30D-55) showed good gastro-resistant performance in both 0.1 N HCl and pH 4.5 media, while immediate release profiles with more than 85% of ESO being released in less than 30 min were obtained. The effect of cellulose-based sub(seal)-coating polymers, (namely, hydroxypropyl cellulose and hydroxypropylmethyl cellulose) on formulation's storage stability at 40 ± 2 °C/75 ± 5%RH indicated that only hydroxypropylmethyl cellulose was able to stabilize ESO delayed-release formulations in terms of assay, dissolution, impurities, and gastro-resistance performance. Finally, scanning electron microscopy (SEM) analysis revealed smooth and homogeneous external surface/coating layers in all three levels (drug-, sub(seal)-, and enteric- coating), while x-ray diffraction showed no polymorphic transformations.

Development of a New Aprepitant Liquisolid Formulation with the Aid of Artificial Neural Networks and Genetic Programming.

In the present study, liquisolid formulations were developed for improving dissolution profile of aprepitant (APT) in a solid dosage form. Experimental studies were complemented with artificial neural networks and genetic programming. Specifically, the type and concentration of liquid vehicle was evaluated through saturation-solubility studies, while the effect of the amount of viscosity increasing agent (HPMC), the type of wetting (Soluplus® vs. PVP) and solubilizing (Poloxamer®407 vs. Kolliphor®ELP) agents, and the ratio of solid coating (microcrystalline cellulose) to carrier (colloidal silicon dioxide) were evaluated based on in vitro drug release studies. The optimum liquisolid formulation exhibited improved dissolution characteristics compared to the marketed product Emend®. X-ray diffraction (XRD), scanning electron microscopy (SEM) and a novel method combining particle size analysis by dynamic light scattering (DLS) and HPLC, revealed that the increase in dissolution rate of APT in the optimum liquisolid formulation was due to the formation of stable APT nanocrystals. Differential scanning calorimetry (DSC) and attenuated total reflection FTIR spectroscopy (ATR-FTIR) revealed the presence of intermolecular interactions between APT and liquisolid formulation excipients. Multilinear regression analysis (MLR), artificial neural networks (ANNs), and genetic programming (GP) were used to correlate several formulation variables with dissolution profile parameters (Y 15min and Y 30min) using a full factorial experimental design. Results showed increased correlation efficacy for ANNs and GP (RMSE of 0.151 and 0.273, respectively) compared to MLR (RMSE = 0.413).

Development of a Novel Amorphous Agomelatine Formulation With Improved Storage Stability and Enhanced Bioavailability.

The present work describes the development of a novel formulation of amorphous agomelatine (AGM) that exhibits enhanced in vitro dissolution rate and bioavailability, as well as improved storage stability. AGM was loaded on a mixture of microcrystalline cellulose with a high specific surface area excipient, namely colloidal silicon dioxide, employing a wet granulation method, and the resultant AGM granules were subsequently formulated into immediate release film-coated tablets. Modulated temperature differential scanning calorimetry, hot-state light microscopy, powder X-ray diffraction, attenuated total reflectance FTIR, and micro-Raman spectroscopy revealed that the active pharmaceutical ingredient existed primarily in the amorphous state within the prepared formulations, with some crystals of polymorph I also present. Accelerated stability studies for up to 6 months in alu-alu blisters showed good physicochemical stability during storage. Finally, in vitro dissolution studies and clinical trials in healthy human volunteers showed a remarkable increase in the in vitro dissolution rate and a ∼1.5-fold increase in bioavailability, respectively, compared to the marketed product.

Effect of 5-HT7 receptor blockade on liver regeneration after 60-70% partial hepatectomy.

BACKGROUND: Serotonin exhibits a vast repertoire of actions including cell proliferation and differentiation. The effect of serotonin, as an incomplete mitogen, on liver regeneration has recently been unveiled and is mediated through 5-HT2 receptor. The aim of the present study was to investigate the effect of 5-HT7 receptor blockade on liver regeneration after partial hepatectomy. METHODS: Male Wistar rats were subjected to 60-70% partial hepatectomy. 5-HT7 receptor blockade was applied by intraperitoneal administration of SB-269970 hydrochloride two hours prior to and sixteen hours after partial hepatectomy and by intraperitoneal administration of SB-258719 sixteen hours after partial hepatectomy. Animals were sacrificed at different time points until 72 h after partial hepatectomy. Liver regeneration was evaluated by [(3)H]-thymidine incorporation into hepatic DNA, the mitotic index in hematoxylin-eosin (HE) sections and by immunochemical detection of Ki67 nuclear antigen. Reversion of 5-HT7 blockade was performed by intraperitoneal administration of AS-19. Serum and liver tissue lipids were also quantified. RESULTS: Liver regeneration peaked at 24 h ([(3)H]-thymidine incorporation into hepatic DNA and mitotic index by immunochemical detection of Ki67) and at 32 h (mitotic index in HE sections) in the control group of rats. 5-HT7 receptor blockade had no effect on liver regeneration when applied 2 h prior to partial hepatectomy. Liver regeneration was greatly attenuated when blockade of 5-HT7 receptor was applied (by SB-258719 and SB-269970) at 16 h after partial hepatectomy and peaked at 32 h ([(3)H]-thymidine incorporation into hepatic DNA and mitotic index by immunochemical detection of Ki67) and 40 h (mitotic index in HE sections) after partial hepatectomy. AS-19 administration totally reversed the observed attenuation of liver regeneration. CONCLUSIONS: In conclusion, 5-HT7 receptor is a novel type of serotonin receptor implicated in hepatocyte proliferation.

The emerging role of serotonin in liver regeneration.

Serotonin has a multifunctional role in many different organs serving either as a neurotransmitter in the central nervous system or a paracrine factor in the gastrointestinal tract. Over 90% of serotonin is synthesised in the enterochromaffin cells of the intestine and subsequently taken up by platelets. The involvement of platelet-derived serotonin in liver mass restoration after partial hepatectomy or toxic injury has been greatly investigated during the last decade. There is a growing body of evidence implicating serotonin in hepatic regeneration through altered expression of serotonin receptor subtypes in the liver. This review article provides a brief overview on the current knowledge about the actions of serotonin in liver regeneration.

Acetaminophen-induced liver injury and oxidative stress: protective effect of propofol.

BACKGROUND AND OBJECTIVE: We evaluated the effects of propofol on oxidative stress and acute liver injury and regeneration produced by acetaminophen administration in rats. METHODS: Acetaminophen (3.5 g kg(-1)) was administered by gastric tube to 50 adult male Wistar rats. One minute before acetaminophen, propofol was administered intraperitoneally (60 mg kg(-1)) to 25 rats and diethyl ether to the other 25 animals. All rats were sacrificed. Markers of oxidative stress (malondialdehyde levels, cholesterol/high-density lipoprotein cholesterol fraction and glutathione-S-transferase-pi activity), liver injury (aspartate aminotransferase alanine aminotransferase and alkaline phosphatase and histological signs of inflammation and in-situ apoptosis) and liver regeneration (rate of [3H]thymidine incorporation into hepatic DNA, activity of liver thymidine kinase and mitotic index in hepatocytes) were determined. Unpaired Student's t-test and one-way analysis of variance were used for statistical analysis and a P value of 0.05 or less was considered significant. RESULTS: All markers of oxidative stress were significantly decreased in propofol-treated animals. Biochemical and histological markers of liver injury and regeneration in propofol-treated animals did not show any significant decrease compared with those observed in the control group. CONCLUSION: The antioxidant capacity of propofol, verified in our study, did not manage to prevent liver injury and accelerate regeneration after acetaminophen administration in rats.

Platelet activating factor (PAF) antagonism with ginkgolide B protects the liver against acute injury. importance of controlling the receptor of PAF.

Platelet activating factor (PAF) is an ubiquitous phospholipid that acts as a mediator of numerous pathophysiological conditions, including hepatotoxicity. The present study has been conducted to evaluate the eventual role of the platelet activating factor in post-acetaminophen intoxication of liver, using ginkgolide B, BN52021, a selective PAF receptor antagonist. One group of rats was treated with a toxic dose of acetaminophen (APAP) (3.5 g/kg b.w.) (control group) and a second one with the same dose of APAP followed by a dose of ginkgolide B, BN52021 (10 mg/kg b.w.) (BN52021-treated group). The animals were killed at 8, 16, 24, 32 and 40 h after treatment. APAP was found to cause an acute hepatic injury, evident by alterations of biochemical (serum enzymes: ALT, AST and ALP) and liver histopathological (degree of inflammation and apoptosis) indices, which was followed by liver regeneration evident by three independent indices ([3H] thymidine incorporation into hepatic DNA, liver thymidine kinase activity and hepatocyte mitotic index). Hepatic levels of malondialdehyde and serum cholesterol/HDL cholesterol fraction were also measured as parameters of oxidant-antioxidant balance. The protected effects of ginkgolide B were qualified during post treatment time by: (1) reduction of oxidative stress, (2) high decrease of hepatic injury, and (3) decrease of regenerating activity. These results indicate that PAF may play an important role in APAP-induced liver injury and regeneration, and that the use of ginkgolide B attenuates liver damage providing important means of improving liver function following acetaminophen intoxication.

VEGF isoforms and receptors expression throughout acute acetaminophen-induced liver injury and regeneration.

Acetaminophen (APAP) is a widely-used analgesic and a known hepatotoxic agent. Vascular endothelial growth factor (VEGF) is a growth factor with multiple functional roles. VEGF plays an important role in angiogenesis and hepatic regeneration. The aim of this study was to determine the expression of VEGF isoforms and its receptors throughout liver regeneration after the administration of a toxic dose of APAP in rats. Ten groups of adult male rats received a dose of 3.5 g/kg b.w. of APAP per os. The rats were killed post administration at 0-288 h. Blood and liver tissue were extracted. Determination of serum transaminases and alkaline phosphatase activities was performed. Liver injury and regeneration were assessed with hematoxylin-eosin specimens, morphometric analysis, hepatic thymidine kinase assay and Ki-67 expression. Reverse transcription-polymerase chain reaction and immunohistochemical methods were used for assessment of VEGF isoforms and receptors differential expression. High activities of aspartate aminotransferase were observed at 24 and 36 h with another peak of activity at 192 h post administration. Alanine aminotransferase was highest at 36 h. Alkaline phosphatase was increased post 24 h being higher at 72,192 and 240 h. Centrilobular necrosis was observed at 48-72 h and thorough restoration of the liver microarchitecture was observed at 288 h. Liver regeneration lasted from 24-192 h according to the results from thymidine kinase activity and Ki-67 expression. VEGF and VEGF receptor-2 m-RNA levels presented with a three-peak pattern of expression at 12-24, 72-96 and 192-240 h post administration. Significant difference was noted between periportal and centrilobular immunohistochemical expression. VEGF proves to play a critical role during APAP-induced liver regeneration as it presents with three points of higher expression. The first two time points are associated with the initial inflammatory reaction to the noxious stimulus and the hepatocyte regenerative process where as the third one is indicative of the potential involvement of VEGF in processes of remodeling.