Aloin delivery on buccal mucosa: ex vivo studies and design of a new locoregional dosing system.

CONTEXT: Chemoprevention of potential malignant disorders or cancerous lesions that affect oral mucosae requires extended duration of treatment. Locoregional delivery of natural products could represent a promising strategy for this purpose. OBJECTIVE: To investigate the aptitude of aloin to permeate through, or accumulate in, the buccal mucosa and to develop a new prolonged oro-mucosal drug delivery system. MATERIALS AND METHODS: Permeation/accumulation of aloin from Curacao Aloe (containing 50% barbaloin) was evaluated ex vivo, using porcine buccal mucosa as the most useful model to simulate human epithelium. Oro-mucosal matrix tablets were prepared by dispersing aloin (10% w/w) in Eudragit® RS 100 as, biocompatible, low permeable, pH-independent, and non-swelling polymer. The prepared tablets were evaluated for drug-polymer compatibility, weight variation, drug uniformity content, diameter, thickness, hardness, friability, swelling, mucoadhesive strength, and drug release. RESULTS: Aloin has low tendency to cross buccal mucosa, permeation is marginal, and high drug amounts remain entrapped into the epithelium. Matrix tablets characteristics were in agreement with pharmacopoeial requirements. Drug release showed highly reproducible Higuchian profile. Delivery through matrix tablets promoted drug accumulation in the mucosal tissue. DISCUSSION AND CONCLUSION: Following application of matrix tablets on porcine buccal mucosa, the amount of discharged drug recovered in the tissue should be sufficient to produce the desired effects, providing therapeutic drug levels directly at the site of action. Aloin-loaded tablets are valid candidates for prevention/treatment of potentially malignant disorders and oral cancer and could potentially lead to clinically relevant drug delivery system as coadjuvant of conventional chemotherapy/radiation therapy.

Oral local drug delivery and new perspectives in oral drug formulation.

Modern pharmaceutical science has provided us with a wide range of substances to be administered with a wide large variety of dosage forms. Local drug delivery systems have been used for a long time; in particular, for the local therapy of diseases affecting the oral cavity. Although these diseases are often extremely responsive to local therapy, the mouth often presents various difficulties in the application of topical compounds (owing to saliva and the mouth's different functions), resulting in a short retention time of dosage forms with a consequent low therapeutic efficacy. To resolve these limitations, research today concentrates on the development of bioadhesive formulations. This review focuses on the permeability features of oral mucosa, the rationale of oral local drug delivery, and new potential bioadhesive local delivery systems. Furthermore, the most promising mucoadhesive systems proposed to locally treat oral diseases are discussed.

Medium-term culture of primary oral squamous cell carcinoma in a three- dimensional model: effects on cell survival following topical 5-fluororacile delivery by drug-loaded matrix tablets.

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.

Bioavailability in vivo of naltrexone following transbuccal administration by an electronically-controlled intraoral device: a trial on pigs.

Naltrexone (NLX), an opioid antagonist, is widely used in the treatment of opiate addiction, alcoholism and smoking cessation. Its current peroral administration induces various adverse side effects and has limited efficacy since bioavailability and patient compliance are poor. The development of a long-acting drug delivery system of NLX may overcome the current drawbacks and help in the improvement of treatment of addiction. The primary endpoints of this study were: a) to compare the NLX bioavailability and pharmacokinetics after delivering a single transbuccal dose, released by a prototype of intraoral device, versus an intravenous (I.V.) bolus of the same drug dose; b) to verify the functioning of a prototype of a new intraoral device in vivo; c) to evaluate the permeation enhancement effect of iontophoresis; d) to assess any histomorphological changes in the buccal mucosa after transbuccal delivery. The system was tested on 6 pigs in a cross-over trial. Venous blood samples were drawn at a fixed timetable from the beginning of drug administration and analyzed for the presence of NLX, using an LC/MS/MS method. A punch biopsy was performed for histological analysis after the final experiment. The administration of I.V. NLX induced a sharp increase in blood levels after 5 min and then a steep decrease. In contrast, transmucosal delivery resulted in a gradual increase in blood NLX levels, reaching its peak after 90 min, followed by a slow decrease. After 6h the blood levels of NLX delivered through the buccal mucosa were higher as compared to I.V. administration. No signs of flogosis or tissue damage were histologically highlighted. These results suggest that buccal delivery by an intraoral electronic device could potentially induce long-lasting, continuous and controlled blood levels of NLX, avoiding at the same time spikes of drug plasma levels typical of the I.V. administration route.

5-Fluorouracil buccal tablets for locoregional chemotherapy of oral squamous cell carcinoma: formulation, drug release and histological effects on reconstituted human oral epithelium and porcine buccal mucosa.

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.

Evaluation of galantamine transbuccal absorption by reconstituted human oral epithelium and porcine tissue as buccal mucosa models: part I.

Over the last decade, interest in delivering drugs through buccal mucosa has increased. As a major limitation in buccal drug delivery could be the low permeability of the epithelium, the aim of this study was to evaluate the aptitude of galantamine, useful in Alzheimer's disease, to penetrate the buccal mucosa. The evaluation of the ability of galantamine to permeate through the buccal epithelium was investigated using two permeation models. Firstly, in vitro permeation experiments were carried out using reconstituted human oral non-keratinised epithelium and Transwell diffusion cells system. Results were validated by ex vivo experiments using porcine buccal mucosa as membrane and Franz type diffusion cells as permeation model. The entity of buccal permeation was expressed in terms of drug flux (J(s)) and permeability coefficients (K(p)). Data collected by in vitro and ex vivo experiments were in agreement and suggested that buccal mucosa does not block diffusion of galantamine. The effects of drug application on histology of tissue specimens used in every experiment were also studied: no sign of flogosis and no significant cytological or architectural changes were highlighted.