Use of Permeapad® for prediction of buccal absorption: A comparison to in vitro, ex vivo and in vivo method

The present work explores the usefulness of Permeapad (R) for prediction of buccal absorption. Permeability studies with the model drug metoprolol were carried out using the Permeapad (R) barrier at pH values 7.4; 8.5; 9.0, and 9.5. It was confirmed that Permeapad (R) can withstand these conditions, and as expected, a clear increase in permeability was found with increasing pH. The permeation results across Permeapad (R) were compared to published in vitro, ex vivo and in vivo studies for the same formulations. Results showed that the permeability of metoprolol using the Permeapad (R) barrier correlated very well to both in vitro and ex vivo studies, (r(2) = 0.98 and 0.97), respectively. Furthermore, excellent in vitro in vivo correlation IVIVC (r(2) = 0.98) was obtained when comparing apparent permeability coefficient to the absolute bioavailability of metoprolol administered buccally to mini-pigs. Results indicate that Permeapad (R) can be used to mimic the buccal absorption of metoprolol as a faster and less laborious method as compared to any of the other mentioned methods. (C) 2016 Elsevier B.V. All rights reserved.