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

Synthesis and in vitro studies on a potential dopamine prodrug

Dopamine delivery to the central nervous system (CNS) undergoes the permeability limitations of blood-brain barrier (BBB) which is a selective interface that excludes most water-soluble molecules from entering the brain. Neutral amino acids permeate the BBB by specific transport systems. Conden- sation of dopamine with neutral amino acids could afford potential prodrugs able to interact with the BBB endogenous transporters and easily enter the brain. The synthesis and characterization of the dopamine derivative 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (7) is de- scribed. The chemical and enzymatic stability of 7 was evaluated. The molecular weight (300 Da) and Log P app (0.76) indicated that the physico-chemical characteristics of compound 7 are adequate to cross biological membranes. Compound 7 was enzymatically cleaved to free dopamine in rat brain homogenate (t 1/2 \ubc 460 min). In human plasma, the t 1/2 of 7 was estimated comparable to that re- ported for l -DOPA. In view of a possible oral administration of 7, studies of its chemical behavior under conditions simulating those of the gastrointestinal tract showed that no dopamine production occurred; furthermore, 7 is able to permeate through a simulated intestinal mucosal membrane. The collected data suggest that compound 7 could be considered a very valuable candidate for subse- quent in vivo evaluation

Ocular gelling microspheres: in vitro Precorneal retention time and drug permeation through reconstituted corneal epithelium

Purpose: The model drug norfloxacin (NOR)was encapsulated into trehalose (TRH) and hydroxyethylcellulose(NAT) microspheres to obtain a novel gelling ophthalmic delivery system for prolonged release on corneal tissue. Methods: We assessed NOR release from microspheres, prepared by the emulsion-solvent evaporation method. A new in vitro tear turnover model, including inserts containing reconstituted human corneal epithelium (RHC), was designed to evaluate the TRH/NAT microspheres\u2019 precorneal retention time. Bioadhesive properties of TRH/NAT microspheres were validated by using drug-loaded microspheres prepared with gelatine (GLT) commonly used as reference material in adhesion studies. Results: In vitro drug release showed a typical trend of swelling systems. Precorneal retention tests showed that TRH/NAT microspheres maintained fluorescence in tear fluid for 81.7 min, whereas TRH/GLT microspheres and water solution maintained fluorescence for 51.8 and 22.3 min, respectively. NOR released from microspheres permeated throughout RHC slower (Js = 23.08 \u3bc g/cm2h) than NOR from commercial eye drops Js = 42.77 \u3bc g/cm2h) used as the control. Conclusions: Adequate drug concentrations in aqueous humor could be prolonged after the administration of TRH/NAT/NOR microspheres. Good bioadhesive properties of the system and slow drug release on corneal surface might increase ocular NOR bioavailability