An evaluation of film coating materials and their predicted oro-esophageal gliding performance for solid oral dosage forms

Oral drug therapy is generally provided in the form of solid oral dosage forms (SODF) that have to be swallowed intact and move throughout the oro-esophageal system until reaching the stomach. Previous studies have provided evidence that the surface characteristics of SODF play an important role during oro-esophageal transit, while their nature may govern the degree of interaction (adhesiveness) with the esophageal tissue. In order to better predict the synergy of SODF surface coatings to the esophageal mucosa during drug administration therapy, an in vitro system has been implemented to investigate their gliding performance across an artificial mucous layer. Coating formulations comprised of different film-forming and slippery-inducing agents were evaluated using the established in vitro artificial mucous system. Polyvinyl alcohol (PVA), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC) and Kollicoat IR (K-IR) were applied as film-forming agents, whereas sodium alginate (SA), carrageenan (CA) and gellan gum (GG) were evaluated both as film-forming and slippery-inducing agents. Carnauba wax (CW), lecithin (LE), xanthan gum (XG) and sodium lauryl sulfate (SLS) were applied as slippery-inducing agents. Two polar wax coating materials were also investigated for their gliding performance. GG displayed suitable gliding performance when applied as film-forming agent, being this effect enhanced when combined with CW/SLS and XG, as slippery-inducing agents. Optimal performance was also demonstrated by the polar waxes. The multivariate approach applied allowed a higher granularity in the analysis of the gliding results and supported a better identification of combinations of excipients and respective concentrations required for improved gliding performance, as such, the obtained gliding results support the identification of coating materials and their suitable combinations that are predicted to improve in vivo swallowing safety.