CaCO2 cells were maintained by media replacement in both chambers every other

day for 14 days, and subsequently, daily for up to 21 days. The integrity of the monolayer selleck chemicals formed was assessed by trans-epithelial electrical resistance (TEER) readings employing a Millicell (MilliPore, Bedford, MA). Monolayers registering net TEER values ranging between 400 and 500 Ω were used for permeation assay. Before the permeation study, CaCO2 monolayer integrity and permeability were assessed using the Millicell and Lucifer yellow respectively. Permeation was carried out with 10 μg/ml (0.5 ml) of C-DIM-5 or C-DIM-8 (in pH-adjusted HBSS-HEPES buffer) and 1.5 ml of blank HBSS-HEPES buffer (pH 7.4) added to the apical and basolateral compartments respectively. The transwells were perfused with 5% CO2 in a humidified 37 °C atmosphere under constant stirring at 50 rpm. Collection of permeated samples (200 μl) from the basolateral compartments were done at 2 h. The samples were injected into a Symmetry C18 column

of an HPLC under an isocratic ZD1839 supplier flow of 1 ml/min in an acetonitrile:water (70:30) mobile phase and detection done at a wavelength of 240 nm. Apparent permeability (Papp) was computed thus: Papp=(([C]×Vb)/([C]a×Va))/(T×Va/A)Papp=(([C]×Vb)/([C]a×Va))/(T×Va/A) where [C] = drug concentration in acceptor compartment; Vb = volume of fluid in acceptor compartment; [C]a = drug concentration in donor compartment; Va = volume of fluid in donor compartment; T = time; and A = surface area of transwell membrane. Aqueous formulations suitable for nebulization were prepared by dissolving C-DIM-5 (50 mg) in 0.5 ml ethanol and 500 mg of vitamin E TPGS and diluting up to 10 ml with distilled water to obtain a 5 mg/ml solution of Thiamine-diphosphate kinase C-DIM-5. This was used for in vitro cytotoxicity

studies and aerodynamic characterization. A 5 mg/ml nebulizing solution was prepared and used for animal studies and comparable formulations of C-DIM-8 were also prepared. An eight-stage Anderson cascade impactor (ACI), Mark II was used for particle size assessment. Impactor plates were coated with 10% pluronic-ethanolic solution to mitigate particle rebound. The formulation was nebulized using a PARI LC STAR jet nebulizer at a dry compressed air flow rate of 4 l/min for 5 min into the cascade impactor at a flow rate of 28.3 l/min. Aerosol particles deposited along the ACI (throat, jet stage, plates on impactor stages 0–7, and filter) were collected by washing with 5 ml of mobile phase comprising acetonitrile:water (70:30) and analyzed by high performance liquid chromatography (HPLC). The analysis was performed on a Waters HPLC system using a Symmetry C18 column (5 μm, 4.6 × 250 mm) with a Nova-Pack C8 guard column at a wavelength of 240 nm and flow rate of 1 ml/min. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were computed from the obtained impactor data utilizing a validated protocol ( Patlolla et al., 2010).