Sublingual permeability of model drugs in New Zealand White Rabbits: In Vitro-In vivo correlation

This study investigated sublingual drug permeation and administration using five model drugs with diverse physicochemical properties, employing New Zealand White Rabbit sublingual mucosa for in vitro experiments and New Zealand White Rabbits for in vivo studies. The research aimed to determine key permeation parameters, specifically permeability and lag time. A strong linear correlation (r = 0.93, n = 5) was established between in vitro permeability and the distribution coefficient of the model drugs at pH 6.8. The study revealed no significant difference between in vitro and in vivo permeability, suggesting that in vitro studies can reliably predict in vivo permeability for these drugs. However, the in vivo lag time was significantly shorter than the in vitro lag time due to the presence of capillaries in the sublingual mucosa, which provided direct access to the systemic circulation and the absence of an aqueous boundary layer.