Novel wound models for characterizing ibuprofen release from foam dressings

The purpose of the present study was to design and characterize low exudate level wound (LEW) and high exudate level wound (HEW) in vitro models by means of investigating therapeutic substance release from exudate-absorbing formulations. Biatain®Ibu foam dressing was used to characterize in vitro release of ibuprofen within the models and also for in vitro–in vivo correlation (IVIVC) studies. Ibuprofen release was described by zero order rate constants of 0.0147 for 1 day and 0.0038 mg/cm2 h for 3 days in HEW and LEW models, respectively. The release is suggested to be controlled by ibuprofen diffusion from the dressing in the HEW model, whereas fluid absorption is rate-limiting in the LEW model. Ibuprofen release, from Biatain®Ibu foam dressings in vivo, is within the same ranges as in vitro. Thus, it is suggested that, depending on the level of exudate, the in vivo release of ibuprofen depends on ibuprofen diffusion from and absorption of exudates to the dressings. Consequently, both the HEW and LEW in vitro models should be applied in order to fully characterize ibuprofen release from Biatain®Ibu foam dressings. Future studies may show whether these in vitro models can be used to characterize therapeutic substance release from exudate-absorbing formulations in general.