Formulation, characterization and pulmonary deposition of nebulized celecoxib encapsulated nanostructured lipid carriers

Abstract

The aim of the current study was to encapsulate celecoxib (Cxb) in the nanostructured lipid carrier (Cxb-NLC) nanoparticles and evaluate the lung disposition of nanoparticles following nebulization in Balb/c mice. Cxb-NLC nanoparticles were prepared with Cxb, Compritol, Miglyol and sodium taurocholate using high-pressure homogenization. Cxb-NLC nanoparticles were characterized for physical and aerosol properties. In-vitro cytotoxicity studies were performed with A549 cells. The lung deposition and pharmacokinetic parameters of Cxb-NLC and Cxb solution (Cxb-Soln) formulations were determined using the Inexpose system and Pari LC star jet nebulizer. The particle size and entrapment efficiency of the Cxb-NLC formulation were 217+/-20nm and >90%, respectively. The Cxb-NLC released the drug in controlled fashion, and in-vitro aerosolization of Cxb-NLC formulation showed an FPF of 75.6+/-4.6%, MMAD of 1.6+/-0.13microm and a GSD of 1.2+/-0.21. Cxb-NLC showed dose and time dependent cytotoxicity against A549 cells. Nebulization of Cxb-NLC demonstrated 4 fold higher AUC(t)/D in lung tissues compared to the Cxb-Soln. The systemic clearance of Cxb-NLC was slower (0.93l/h) compared to the Cxb-Soln (20.03l/h). Cxb encapsulated NLC were found to be stable and aerodynamic properties were within the respirable limits. Aerosolization of Cxb-NLC improved the Cxb pulmonary bioavailability compared to solution formulation which will potentially lead to better patient compliance with minimal dosing intervals.

Figure 1

Differential Scanning Calorimetry of Cxb formulations. A) Cxb alone and in combination with the lipid exipients 1) Celecoxib pure drug 2) Compritol + Miglyol 3) Cxb-compritol physical mixture B) NLC formulation with and without Cxb, 4) blank NLC formulation 5) Cxb-NLC formulation.

Figure 2

In-vitro drug release of Cxb from Cxb-Soln and Cxb-NLC formulations.

Figure 3

In-vitro cytotoxicity profile of Cxb-NLC formulation in A549 cells after A) 24 h B) 48 h C) 72 h of treatment. Cells were treated with various concentrations of Cxb-NLC and Cxb-Soln formulations and cytotoxicity was determined using crystal violet dye assay as described in Materials and Methods. A plot of the percentage of cell survival versus Cxb concentrations used for the determination of IC₅₀ values. Values represent the Mean ± SD of at least three separate determinations for each treatment group.

Figure 4

Effect of time on the lung deposition of Cxb-Soln and Cxb-NLC formulations. Following nebulization for 30 min, at regular time intervals 5, 10, 20 and 30 min the mice lungs were collected and the amount of Cxb deposited was determined using method as specified in the Materials and Methods section. The data represent the Mean ± SD (n=6). ● Cxb-Soln and □ Cxb-NLC.

Figure 5

Lung deposition of Cxb-Soln and Cxb-NLC formulations after nebulization for 30 min using nose only Inexpose™ system and Pari LC Star jet nebulizer in Balb/c mice. The data represent the percent dose of Cxb deposited per lung tissue was plotted against time (Mean ± SD), n=6. ● Cxb-Soln and □ Cxb-NLC, *p < 0.05; **p < 0.01; ***p < 0.001.

Figure 6

Lung disposition of DID-oil fluorescent dye loaded NLC (Fl-NLC) formulation in Balb/c mice. Fl-NLC formulation was nebulized to mice and the lungs were collected and processed for confocal microscopy as described in Methodology section. The fluorescent dye was visualized with confocal microscope. I) bright field II) fluorescent mode.

Figure 7

Plasma pharmacokientics of Cxb-Soln and Cxb-NLC formulations after nebulization for 30 min using nose only Inexpose™ system and Pari LC Star jet nebulizer in Balb/c mice. ● Cxb-Soln and □ Cxb-NLC, *p < 0.05; **p < 0.01.