title: Influence of salivary washout on drug delivery to the oral cavity using coated microneedles: An in vitro evaluation.
abstract: The objective of this study was to determine whether in buccal tissues, after insertion and removal of coated microneedles, the presence of saliva over the insertion site can lead to loss of the deposited drug, and if saliva can influence in vitro permeation of the drug across the tissue. Microneedles were coated with sulforhodamine (SRD), which was used as a model drug, and inserted in to porcine buccal mucosa in vitro. Fluorescence microscopy was used to study microneedle coating quality and the diffusion of SRD through the mucosa. Permeation experiments were conducted for simulated dynamic or static salivary flow by adding 100μL/h or 100, 200 or 300μL of phosphate buffered saline (PBS) in the donor compartment of the Franz diffusion cells, into which buccal tissue after insertion of SRD-coated microneedles was placed. Microscopy showed that microneedles were uniformly coated with SRD and that SRD was successfully delivered in to the mucosa. Some SRD remained in the tissue even after 24h, despite presence of PBS on top of the coated microneedle insertion site. It was found that salivary washout can result in loss of drug that has been deposited in oral cavity mucosal tissues using coated microneedles, and presence of fluid over the coated microneedle insertion site can increase flux across the tissue. Thus, it is advisable to include salivary flow during in vitro studies related to the use of coated microneedles for drug delivery to the oral cavity in order to not obtain misleading results.
authors: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors: Luciano
authors: L
authors: Serpe
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, USA.
authors: Amit
authors: A
authors: Jain
authors: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors: Cristina Gomes
authors: CG
authors: de Macedo
authors: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors: Maria Cristina
authors: MC
authors: Volpato
authors: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors: Francisco Carlos
authors: FC
authors: Groppo
authors: Department of Chemical Engineering, Texas Tech University, Lubbock, TX, USA. Electronic address: harvinder.gill@ttu.edu.
authors: Harvinder Singh
authors: HS
authors: Gill
authors: Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil. Electronic address: mfranz@unicamp.br.
authors: Michelle
authors: M
authors: Franz-Montan
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes / Q000008:administration & dosage; D066298:In Vitro Techniques; D008845:Microinjections; D009061:Mouth Mucosa; D009339:Needles; D012235:Rhodamines / Q000008:administration & dosage; D012463:Saliva; D013552:Swine
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines
keywords: Diffusion; In vitro model; Microneedles; Oral mucosa drug delivery; Permeability