Nasal cavity represents a simple non-invasive route for administration of drugs with local or systemic effect, which bypasses the first-pass metabolism of oral drugs. Cell models are simple and useful tools for studying in vitro-in vivo correlations, drug permeability, mechanisms of transport and cytotoxicity. The aim of our research was to measure the permeability of locally active drugs for local treatment of the nasal mucosa in the apical-basolateral direction and to evaluate the effect of the formulation on their permeability. Widely used cell models of nasal epithelium are RPMI 2650 and Calu-3 cell lines. When cultured under air-liquid conditions, they form an epithelium very similar to human nasal mucosa. Cells were grown on a semipermeable membrane. During cultivations, growth and formation of cell layers were monitored with the invert light microscopy. Adequate cellular integrity was confirmed by a measurement of transepithelial electrical resistance and permeability of the paracellular marker Lucifer Yellow. Permeability of substances was expressed with apparent permeability coefficient Papp. We demonstrated that the different dosage systems of the same formulation composition (e.g. nasal drops and spray) do not affect the permeability. The strength of the drug formulation in the same vehicle does also not affect the permeation for drugs with passive transport mechanism. By comparing the untreated formulations with formulation dilutions and standard solutions and other formulations with same active ingredient, the effect of the formulation was demonstrated. Different formulation composition or dilution of samples can result in different concentration of active substance and/or excipients. This leads to the decrease or increase in permeability. The difference between suspensions and solutions was observed. Moreover, the compounds were classified as good or poorly permeable and exhibited no toxic effect on respiratory cell models.
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