Modification of microenvironmental pH of nanoparticles for enhanced solubility and oral bioavailability of poorly water-soluble celecoxib.

This study aimed to develop a novel pH-modified nanoparticle with improved solubility and oral bioavailability of poorly water-soluble celecoxib by modifying the microenvironmental pH. After assessing the impact of hydrophilic polymers, surfactants and alkaline pH modifiers on the drug solubility, copovidone, sodium lauryl sulfate (SLS) and meglumine were chosen. The optimal formulation of solvent-evaporated, surface-attached and pH-modified nanoparticles composed of celecoxib/copovidone/SLS/meglumine at weight ratios of 1:1:0.2:0, 1:0.375:1.125:0 and 1:1:1:0.2:0.02, respectively, were manufactured using spray drying technique. Their physicochemical characteristics, solubility, dissolution and pharmacokinetics in rats were evaluated compared to the celecoxib powder. The solvent-evaporated and pH-modified nanoparticles converted a crystalline to an amorphous drug, resulting in a spherical shape with a reduced particle size compared to celecoxib powder. However, the surface-attached nanoparticles with insignificant particle size exhibited the unchangeable crystalline drug. All of them gave significantly higher solubility, dissolution, and oral bioavailability than celecoxib powder. Among them, the pH-modified nanoparticles demonstrated the most significant improvement in solubility (approximately 1600-fold) and oral bioavailability (approximately 4-fold) compared to the drug powder owing to the alkaline microenvironment formation effect of meglumine and the conversion to the amorphous drug. Thus, the pH-modified nanoparticle system would be a promising strategy for improving the solubility and oral bioavailability of poorly water-soluble and weakly acidic celecoxib.

Hydroxypropyl-ß-cyclodextrin-based solid dispersed granules: A prospective alternative to conventional solid dispersion.

The purpose of the present study was to develop hydroxypropyl-ß-cyclodextrin (HP-ß-CD)-based solid dispersed granules as a superior system to solid dispersion. The solid dispersed granules and solid dispersion were compared in terms of powder property improvement, solubility increment and oral bioavailability enhancement of poorly water-soluble dexibuprofen. Solid dispersion (drug/HP-ß-CD/Tween80 = 1:7:0.1, weight ratio) and solid dispersed granules (drug/HP-ß-CD/Tween80/Microcrystalline cellulose = 1:7:0.1:4) were fabricated using a spray-dryer and fluid bed granulator, respectively. The HP-ß-CD-based solid dispersed granules significantly improved solubility, dissolution profile and oral bioavailability of dexibuprofen compared to pure drug powder. Moreover, the solid dispersed granules maximised the oral bioavailability of dexibuprofen to the same extent as the solid dispersion. However, considerable improvements of powder and tablet properties were observed in solid dispersed granules as compared with solid dispersion. Therefore, HP-ß-CD-based solid dispersed granules would be a prospective alternative to solid dispersion.