Ex-vivoand in-vitro assessment of mucoadhesive patches containing the gel-forming polysaccharide psyllium for buccal delivery of chlorhexidine base.

The aim of the present study was to evaluate the gel-forming polysaccharide psyllium in the preparation of mucoadhesive patches for the controlled release of chlorhexidine (CHX) to treat pathologies in the oral cavity, using the casting-solvent evaporation technique. A number of different film-forming semi-synthetic polymers, such as sodium carboxymethyl cellulose (SCMC) and hydroxypropylmethyl cellulose (HPMC) were evaluated for comparison. The patch formulations were characterized in terms of drug content, morphology surface, swelling and mucoadhesive properties, microbiology inhibition assay and in vitro release tests. Three ex-vivo testswere carried out using porcine mucosa: an alternative dissolution test using artificial saliva that allows contemporary measurement of dissolution and mucoadhesion, a permeation test through the mucosa and the measurement of mucoadhesion using a Nouy tensile tester, as the maximum force required for the separation of the patch from the mucosa surface. The patches were also examined for determination of the minimum inhibitory concentration in cultures of Escherichia coli and Staphylococcus aureus. All the patches incorporating psyllium were found suitable in terms of external morphology, mucoadhesion and controlled release of the drug: in the presence of psyllium the drug displays prolonged zero-order release related to slower swelling rate of the system.

Assessment of dietary fiber fermentation: effect of Lactobacillus reuteri and reproducibility of short-chain fatty acid concentrations.

This investigation had two aims: (i) to determine the reproducibility of SCFA production of two fibers: wheat dextrin and inulin, in two separate in vitro batch fermentation systems, and (ii) to determine if the addition Lactobacillus reuteri, a probiotic bacterium, enhanced the fermentation of wheat dextrin, inulin, and psyllium using in vitro batch fermentation. Samples were removed at 0, 4, 8, 12, and 24 h. SCFAs were measured by GC. L. reuteri improved inulin's fermentation profile by reducing the total SCFA peak at 4 h and enhancing fermentation at 8 and 12 h. Wheat dextrin and psyllium were largely unaffected. Wheat dextrin's total SCFA and propionate production curves were steady and replicable, but concentration values varied between fermentations. Partially hydrolyzed guar gum (PHGG) and wheat dextrin had similar fermentation patterns from 0-8 h, but PHGG plateaued at 8 h for all measures. Psyllium produced peak SCFA concentrations at 8 h, similar to inulin. L. reuteri could be combined with inulin for enhancing fermentation, but it does not improve wheat dextrin or psyllium fermentation. Wheat dextrin will likely produce similar physiological within a group of individuals due to the reproducibility of fermentation.

Availability of calcium for absorption in the small intestine and colon from diets containing available and unavailable carbohydrates: an in vitro assessment.

An in vitro method simulating conditions in the small intestine and colon was used to study the effects of various carbohydrates on Ca release from basal diet (BD) containing dairy products. During enzymatic digestion of BD, 28.5 +/- 0.3% of the Ca was released. This was reduced by 3, 22 and 27% by adding bread, psyllium or pectin to BD, respectively (P < 0.05). After enzymatic digestion, the residue from BD was fermented releasing 11.9 +/- 1.2% of the Ca, a value which was significantly less than with pectin (13.7 +/- 0.9%) and greater than with psyllium (4.4 +/- 0.2%) addition. The total Ca release ranged from 26.5 +/- 0.8 to 42.2 +/- 1.0% with bread>BD>pectin>psyllium. Lactulose did not differ significantly from BD. These results suggest that carbohydrates may bind Ca and reduce its availability for absorption in the small intestine. However, if the carbohydrate is fermented, bound Ca may be released for potential absorption in the colon, whereas less fermented carbohydrates may continue to bind Ca in the colon. The in vitro method described may be useful for estimating total Ca availability. However, studies in humans are required to validate these results.