Haematology, blood biochemistry, parasites and pathology of common eider (Somateria mollisima) males during a mortality event in the Baltic.

A mortality event at the Christiansø colony in the Baltic proper killed 115 common eiders (Somateria mollissima) in mid-May 2016. To complement previous studies of incubating females, 39 males were necropsied and from a subsample of these a biochemical and haematological profile was obtained. The birds were emaciated and cachexic having a 50% reduction in body mass. Twenty-nine eiders were diagnosed with hydropericardium, 15 had hunger edema, three birds had enteritis and a single air sac infection. All birds were infested with intestinal Polymorphus minutus and 32 of these with the intestinal Trematoda spp. Microscopic parasitic investigations identified endoparasitic trematodes of the families Bucephhalidae, Echinostomidae, Notocotyluridae and Levinsiniella. White blood cell count showed slight heterophilia and lymphopenia while the albumin:globulin ratio (0.28) indicated stress, immune supression and inflammatory reactions supported by a high heterophil:lymphocyte index (13). Declined plasma concentration of glucose, fructosamine, amylase, albumin and protein likewise indicated long-term starvation prior to mortality indicating phase III starvation (catabolism of protein). The dramatic increase in aspartate transaminase, glutamate-dehydrogenase, lactate-dehydrogenase and bile acids indicate liver disorders while dehydration, renal, heart and bone disorders was reflected in the increased uric acid, urea, phosphor and potassium values. These findings show that male eiders undergo long-term starvation and multi organ failure similar to that of incubating females previously reported from the same colony. It increases our knowledge of the physiology of starving eiders and add to our understanding of the recurrent mortality events in the colony that seems to be linked to changes in food availability being an important factor together with a warmer climate in a declining Baltic eider population. We recommend future studies to focus on food composition, migration patterns and environmental changes including parasitic infections and global warming.

Buccal absorption of diazepam is improved when administered in bioadhesive tablets-An in vivo study in conscious Göttingen mini-pigs.

Buccal delivery may be clinically beneficial for compounds with a high gastrointestinal and hepatic first pass metabolism or in situations where a fast systemic absorption is desired. The delivery of a crystalline low soluble compounds, e.g. diazepam, may be limited due to the low volume of saliva available to facilitate solvation in order to drive the permeation of drug through the buccal mucosa. Therefore, the present study investigated the potential benefits of administering diazepam either as an amorphous or as a crystalline form in mucoadhesive tablets to conscious Göttingen mini-pigs. Presentation of the compound in the amorphous form lead to a very fast absorption, however, the obtained bioavailability was at the same level observed following buccal administration of a commercially immediate release tablet. Addition of chitosan, as a mucoadhesive excipient, resulted in a higher absolute bioavailability compared to tablets without chitosan. The absorption rate for the chitosan-based tablets was significant slower, probably due to the slower diffusion of the compound out of the tablet. In vitro release data was able to predict the variations in tmax, but otherwise no correlation could be found between in vitro and in vivo data.

Ex vivo correlation of the permeability of metoprolol across human and porcine buccal mucosa.

The pH partition theory proposes a correlation between fraction of unionized drug substance and permeability. The aim of this study was to compare the permeability of metoprolol and mannitol in ex vivo human and porcine buccal mucosa models at varying pH to validate whether the porcine permeability model is predictive for human buccal absorption. Human (n = 9-10) and porcine (n = 6-7) buccal mucosa were mounted in a modified Ussing chamber, and the kinetics of metoprolol and mannitol transport was assessed for a period of 5.5 h with the pH values of donor medium set at 7.4, 8.5, and 9.0. In addition, hematoxylin-eosin and Alcian blue-van Gieson were used as tissue stains to evaluate the histology and the presence of acidic polysaccharides (e.g., mucins), respectively. The permeability of metoprolol was decreased in human buccal mucosa by almost twofold when compared with porcine buccal mucosa with a positive correlation (r(2) = 0.96) between the permeability assessed in porcine and human buccal mucosa. There was no change in the degree of either epithelial swelling or desquamation when treating with the pH 9.0 donor medium for 5.5 h. These data suggest that buccal mucosa from pigs can be used to predict human buccal absorption.

Conscious and anaesthetised Göttingen mini-pigs as an in-vivo model for buccal absorption - pH-dependent absorption of metoprolol from bioadhesive tablets.

The potential of buccal mucosa as a site for systemic absorption has attracted increased attention in recent years creating a need for new predictive in-vivo models. The aim of this study was to evaluate anaesthetised and conscious Göttingen mini-pigs as a model for buccal drug absorption by testing pH-dependent absorption of metoprolol from a solid dosage form. Buccal tablets buffered to pH 6.2 and pH 8.9, oral liquid and intravenous injection were tested in four conscious and anaesthetised Göttingen mini-pigs in a non-randomised cross-over study. Blood samples were collected and processed before analysis by ultra-performance liquid chromatography with tandem mass spectrometry detection. An ex-vivo flow retention model was applied to study release and retention of the bioadhesive buccal tablets. The Tmax obtained from the two buccal conscious groups (55 ± 5 and 35 ± 5 min) were significantly different to the buccal anaesthetised groups (120 ± 0 and 165 ± 15 min) for buccal tablet pH 6.2 and pH 8.9, respectively. Also, the absolute bioavailability from the anaesthetised buccal tablet pH 8.9 (20.7 ± 4.0%) had a significant increase compared to all other buccal tablet groups. In conclusion, this study showed a pH-dependent absolute bioavailability of metoprolol when administrated as bioadhesive buccal tablets to anaesthetised mini-pigs. The anaesthesia was found to delay the time to reach maximal plasma concentration of metoprolol as compared to the conscious pig model when administrated as buccal tablets.

Azone® decreases the buccal mucosal permeation of diazepam in a concentration-dependent manner via a reservoir effect.

The purpose of this study was to examine concentration-dependent effects of Azone® (AZ) on the buccal absorption of diazepam (DIAZ). Porcine buccal mucosa was placed in modified Ussing chambers and pretreated with 10 µL of 0%, 5%, 20%, and 50% (w/v) AZ in ethanol. DIAZ was administered to the donor chamber either in solution or a chitosan-based gel. The donor chamber disappearance, receptor chamber appearance, and tissue retention of DIAZ were monitored over 2 h by HPLC, with AZ tissue disposition also measured by liquid chromatography-mass spectrometry profiling of tissue cryosections. DIAZ steady-state flux values significantly (p < 0.05) decreased 1.4- and 2.4-fold in 20% and 50% AZ-pretreated tissues, respectively. Only 20% and 50% AZ-pretreated tissues were also accompanied by an increased loss of DIAZ from the donor chamber, suggesting DIAZ was forming a reservoir in the buccal mucosa with higher AZ concentrations. Indeed, the percentage of the initial DIAZ dose remaining in the mucosa following a 2 h experiment was increased 3.0-fold with a 50% AZ pretreatment compared with control. AZ provided a concentration-dependent reservoir for DIAZ in buccal mucosa, resulting in retarded release into the receptor chamber, an approach that may be exploited for controlled release of DIAZ.

A mechanistic based approach for enhancing buccal mucoadhesion of chitosan.

Mucoadhesive buccal drug delivery systems can enhance rapid drug absorption by providing an increased retention time at the site of absorption and a steep concentration gradient. An understanding of the mechanisms behind mucoadhesion of polymers, e.g. chitosan, is necessary for improving the mucoadhesiveness of buccal formulations. The interaction between chitosan of different chain lengths and porcine gastric mucin (PGM) was studied using a complex coacervation model (CCM), isothermal titration calorimetry (ITC) and a tensile detachment model (TDM). The effect of pH was assessed in all three models and the approach to add a buffer to chitosan based drug delivery systems is a means to optimize and enhance buccal drug absorption. The CCM demonstrated optimal interactions between chitosan and PGM at pH 5.2. The ITC experiments showed a significantly increase in affinity between chitosan and PGM at pH 5.2 compared to pH 6.3 and that the interactions were entropy driven. The TDM showed a significantly increase in strength of adhesion between chitosan discs and an artificial mucosal surface at pH 5.2 compared to pH 6.8, addition of PGM increased the total work of adhesion by a factor of 10 as compared to the wetted surface without PGM. These findings suggest that chitosan and PGM are able to interact by electrostatic interactions and by improving the conditions for electrostatic interactions, the adhesion between chitosan and PGM becomes stronger. Also, the three complementary methods were utilized to conclude the pH dependency on mucoadhesiveness.

In vitro, ex vivo and in vivo examination of buccal absorption of metoprolol with varying pH in TR146 cell culture, porcine buccal mucosa and Göttingen minipigs.

This work studied the buccal absorption of metoprolol in vitro, ex vivo and in vivo as a function of buffered pH at 7.4, 8.5, 9.0 and 9.5. Permeability studies showed a correlation (r(2)=0.92) between in vitro TR146 cell culture and ex vivo porcine buccal mucosa in a modified Ussing chamber. A higher apparent permeability was observed at higher pH values, i.e. the more compound that was unionised the higher the permeability. In vivo studies were conducted in anaesthetised Göttingen mini-pigs. A clear influence of pH on the absorption was seen and a significant higher absolute bioavailability was obtained after buccal dosing (58-107%) compared to oral (3%) administration, ranging 58-107% and 3%, respectively. Macroscopically, no local toxic effects were observed by visual inspection of mini-pig cheeks. A very clear level C in vitro in vivo correlation (r(2)=0.98) was obtained between the observed in vitro permeabilities and the bioavailability observed in vivo, suggesting that the two in vitro models have good predictive power for drug delivery, which could be a useful tool for future formulation developments intended for buccal delivery.

Real-time UV imaging of nicotine release from transdermal patch.

PURPOSE: This study was conducted to characterize UV imaging as a platform for performing in vitro release studies using Nicorette® nicotine patches as a model drug delivery system. METHODS: The rate of nicotine release from 2 mm diameter patch samples (Nicorette®) into 0.067 M phosphate buffer, pH 7.40, was studied by UV imaging (Actipix SDI300 dissolution imaging system) at 254 nm. The release rates were compared to those obtained using the paddle-over-disk method. RESULTS: Calibration curves were successfully established which allowed temporally and spatially resolved quantification of nicotine. Release profiles obtained from UV imaging were in qualitative agreement with results from the paddle-over-disk release method. CONCLUSION: Visualization as well as quantification of nicotine concentration gradients was achieved by UV imaging in real time. UV imaging has the potential to become an important technology platform for conducting in vitro drug release studies.