Nasal Drug Delivery In Vitro Studies on Factors Influencing Permeability and Implications on Absorption
Sammanfattning: Nasal delivery is a feasible alternative to oral or parenteral administration for some drugs because of the high permeability of the nasal epithelium, rapid drug absorption across this membrane and avoidance of hepatic first-pass metabolism. The main objective of this thesis was to investigate factors influencing the permeability of the nasal mucosa to various compounds and to evaluate implications for drug absorption via the nasal route. Porcine nasal mucosa mounted in an Ussing chamber system was established as an in vitro model, and glucose, insulin, lidocaine, mannitol, melagatran, nicotine, PEG 4000, propranolol, sumatriptan, verapamil, vinblastine and an aminodiether were used as model compounds. The pharmacokinetics of melagatran and propiomazine were investigated in absorption studies in rats, and the influence of the enhancers SDS and EDTA on melagatran absorption was evaluated and compared with in vitro permeability data. The expression of P-glycoprotein in porcine nasal mucosa was investigated and compared with that in human nasal epithelial biopsies using the Western Blot technique.The results demonstrated that the Ussing chamber model using porcine nasal mucosa has potential as a tool for evaluating mechanisms of nasal absorption and predicting the in vivo effects of absorption enhancers. Moreover, porcine nasal mucosa is comparable to human nasal mucosa in its morphology and P-glycoprotein expression. The in vitro permeability data were found to weakly correlate with literature data on human absorption after nasal administration of the corresponding compounds. In vivo absorption studies of the sedative propiomazine demonstrated that nasal administration of this drug offers an interesting alternative to the oral formulation currently on the market, since the absorption was rapid and the bioavailability was promising. The bioavailability of melagatran in rats was moderate but variable, and responded to the addition of enhancers. Finally, the establishment and characterisation of an in vitro method for prediction of nasal drug absorption, and the investigation of factors influencing nasal membrane permeability and absorption offer substantial contributions for nasal drug delivery.
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