Improving the dissolution rate of a poorly water-soluble drug via adsorption onto pharmaceutical diluents

The purpose of this study was to improve the dissolution rate of poorly water-soluble celecoxib (CXB) via a new adsorption method. CXB was dissolved in a co-solvent (ethanol:dichloromethane = 40:60 v/v) and then adsorbed on the surface of various diluent carriers by wet grinding. The physicochemical properties, such as the morphology and crystal structure, of the resulting adsorption powders were characterized. The adsorption powders were compressed into tablets after the wet granulation process. The in vitro dissolution rate of the CXB-loaded tablet was assessed in intestinal fluid (pH 6.8) containing 1% sodium lauryl sulfate. The differential scanning calorimetry and powder X-ray diffraction data showed that the crystallinity of CXB was maintained in the adsorption powders. Fourier transform infrared spectra indicated a molecular hydrogen-bonding between CXB and the adsorption carriers. Lactose monohydrate was the most effective at improving the dissolution rate of CXB via strong hydrogen bonding, followed by mannitol, Avicel® PH102, A-tab®, and Di-tab®. The CXB-loaded tablet was also stable during storage conditions (ambient: 25 °C, 60% RH, accelerated: 40 °C, 75% RH). Adsorption of CXB onto a hydrophilic diluent carrier provides an effective pharmaceutical strategy to enhance the dissolution rate of CXB-loaded tablets without changing drug crystallinity.

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