Mucoadhesive alginate matrices containing sodium carboxymethyl starch for buccal drug delivery: in vivo and in vitro studies

The aim of this paper was to investigate the development of buccal mucoadhesive tablets (hydrophilic matrices) intended for the local delivery of an antimicrobial drug, chlorhexidine diacetate, in the oral cavity over a prolonged period of time. Sodium alginate was selected as the mucoadhesive polymer. Sodium carboxymethyl starch was used in different weight ratios to modulate the matrix erosion/drug release. The antimicrobial activity of the drug/excipient mixtures was investigated for the minimum inhibitory concentration and minimum candidicidal concentration. Buccal tablets were prepared by direct compression and studied by in vitro drug release and in vitro mucoadhesion tests. The tablets were characterised by a prolonged in vitro drug release. Sodium alginate exhibited good mucoadhesion behaviour. After their in vivo administration, the determination of chlorhexidine in saliva showed that the formulations characterised by the presence of the highest percentage of sodium carboxymethyl starch had the capacity to give a prolonged release of chlorhexidine in the buccal cavity. This behaviour was related to the in vivo erosion of the matrices. These preliminary results indicate that these matrices can be proposed as buccal mucoadhesive systems for the intraoral prolonged delivery of drugs