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The aim of this study was to investigate the potential for systemic administration of Methimazole (MMI) through the buccal mucosa as an alternative route for drug delivery. Considering that the most important restriction in buccal drug delivery could be the low permeability of the mucosa, the ability of MMI to cross the mucosal barrier was assessed. Permeation of MMI through porcine buccal mucosa was investigated ex vivo using Franz type diffusion cells, buffer solution simulating saliva or natural human saliva as donor phase. The collected data suggested that buccal mucosa does not hinder MMI diffusion and the drug crosses the membrane (J(s) = 0.068 mg cm(-2) h(-1) and K(p) = 0.065 cm h(-1)). Matrix tablets, suitable for administration on buccal mucosa, were then designed and prepared by direct compression of MMI loaded matrices (70% w/w) using Eudragit(®) RS 100 as a matrixing, low permeable, pH-independent, mucoadhesive and insoluble agent. The matrix tablets were evaluated in vitro for dissolution; however, the drug was discharged too rapidly from tablets. To obtain drug release rate suitable to maintain constant drug levels in the central compartment the tablets were coated with lipophilic material (glycerol tristearate). In ex vivo permeation experiments, therapeutically MMI plasma levels were obtained when matrix tablets were coated with 0.10 mm thick lipophilic coating film. Coated tablets placed on buccal porcine mucosa provide optimal drug release rate. Coated buccal matrix tablets may represent a potential alternative dosage form for systemic delivery of MMI in hyperthyroidism management.

Tissue-engineered oral mucosal equivalents have been developed for in vitro studies for a few years now. However, the usefulness of currently available models is still limited by many factors, mainly the lack of a physiological extracellular matrix (ECM) and the use of cell populations that do not reflect the properly differentiated cytotypes of the mucosa of the oral cavity. For this reason, we have developed a novel three-dimensional culture model reflecting the normal architecture of the human oral mucosa, with the main aim of creating a better in vitro model where to test cellular responses to drugs administration. This novel 3D cell culture model (3D outgrowth) was set up using an artificial extracellular matrix (Matrigel™ ), allowing the interactions required for proper differentiation of the various citotypes which form the mucosal layer. Biopsies of human oral mucosa, in fragments of about 0.5 mm3, were placed onto 6.5mm Transwells, covered with Matrigel™ and grown in a specific culture medium. A gradual formation of an architectural structure similar to that of the in vivo oral mucosa was observed. Transmission electron and confocal microscopy were employed to characterize the newly developed model: the cell components (keratinocytes and fibroblasts) differentiated properly within the outgrowth and reconstituted, in vitro, the physiological structure of the human oral mucosa, including a stratified non-keratinized squamous layer composed of four different layers, a proper basal membrane and a lamina propria where fibroblasts produce ECM. Moreover, keratinocytes expressed CK5, CK13, CK19 and E-cadherin, whereas fibroblasts expressed collagen type I and IV, laminin and fibronectin. 3D outgrowths could be considered a valid alternative to animal models, and provide useful information for researchers interested in studying the responses of the human oral mucosa to locally delivered drugs or other exogenous treatments.

Since the activity of several conventional anticancer drugs is restricted by resistance mechanisms and dose-limiting side-effects, the design of formulations for local application on malignant lesions seems to be an efficient and promising drug delivery approach. In this study, the effect of locally applied 5-FU on cell death was evaluated both in a SCC4/HEK001 model and in a newly proposed 3D outgrowth model of oral squamous cell carcinoma (OSCC). Initially, the optimal drug dose was established by delivery of solutions containing different amounts of 5-FU. The solution containing 1% (w/v) of 5-FU resulted effective in inducing cell death with complete eradication of cell colonies. Buccal tablets were designed to deliver 5-FU locoregionally to the cancer lesions of the oral cavity. Tablets were prepared using a drug loaded matrix of acrylic/methacrylic acid copolymer containing 1% (w/w) of 5-FU and applied on 3D outgrowths. The drug release from tablets appeared to be sufficient to induce cell death as confirmed by transmission electron microscopy and enzymatic assay (TUNEL). After 120 h of treatment, when about 90% of the drug had been discharged from the tablets into the culture environment, 5-FU caused loss of cell-cell communications and apoptotic cell death. After 192 h, a complete disaggregation of the 3D oral outgrowths and the death of all the cells was observed. Buccal matrix tablets could be considered a promising new approach to the locoregional treatment of OSCC. Risks of systemic toxicity are avoided since very low drug doses are delivered.

A new aminoacidic derivative of valproic acid (VPA) has been synthesized and characterized by analytical and spectral data. The rationale for the preparation of such potential antiepileptic agent is based on the observation that chemical combination of the anticonvulsant pharmacophore, VPA with essential aminoacids could afford more effective and less toxic actives. The synthesis, characterization, physico-chemical parameters functional for crossing Blood Brain Barrier of N-valproyl-L-tryptophan (4) are reported. The Log D (pH7.4) (0.3) indicates that (4) is adequate to cross biological membranes. Its chemical and enzymatic stability were assessed. The experiments indicate high stability of compound (4) at pH conditions of physiological fluids. Moreover, both in plasma and in cerebral enzymatic environments compound (4) doesn't undergo cleavage after 24 h. The anticonvulsant activity of the new compound was assessed against epileptic burst discharges evoked in vitro in rat hippocampal slices (Seizure like events - SLEs) and compared with that of the widely used VPA. Compound (4), even at the lower tested concentration, when compared to VPA, showed an improved protective effect against hippocampal seizures. The collected data suggest that compound (4) could be considered a very valuable candidate for subsequent in vivo evaluation as new potential antiepileptic drug.

5-Fluorouracil (5-FU) is currently used for treatment of oral squamous cell carcinoma (OSCC). 5-FU is given by i.v. although the systemic administration is associated with severe toxic effects and no topical formulations of 5-FU for buccal drug delivery have been reported. In this study we would report the development of buccal tablets suitable for direct application of low-doses of 5-FU on cancer lesions. The topical administration could be effective on tumor area while systemic undesired side effects are avoided. Preliminarily, the limited tendency of 5-FU to cross the buccal tissue was established using reconstituted human oral epithelium (RHOE, in vitro) and porcine buccal mucosa (ex vivo) as mucosal models. The values of steady-state flux and permeability coefficient suggested the scarce aptitude of 5-FU to reach the systemic circulation. Matrix buccal tablets, were designed for 5-FU local delivery, developed and prepared. Release tests showed a highly reproducible Higuchian drug discharge. After tablet administration on buccal tissue specimens, the occurrence of histo-morphological effects of 5-FU was highlighted. Apoptotic events were registered in all samples treated while only negligible amounts of 5-FU permeated the buccal membrane and reached the simulated plasma. The results suggest that loaded matrix tablets containing 5% of 5-FU could be a useful means in topical treatment of OSCC.