Effect of Solubility Improvement via Formation of an Amorphous Composite of Indomethacin and Sulindac on Membrane Permeability.

The importance of permeability as well as solubility of the drug has been recognized in improving the solubility of poorly water-soluble drugs. This study investigated the impact of amorphous composites of indomethacin (IMC) and sulindac (SLD) on the membrane permeability of drugs. The IMC/SLD (1/1) formulation prepared by dry grinding was amorphous with a single glass transition temperature. The Fourier transform IR spectra and Raman spectra revealed formation of hydrogen bonds between the OH group of IMC and the carbonyl group of SLD. These results suggest that an amorphous composite was formed between IMC and SLD through hydrogen bonding. The amount of dissolved IMC and SLD from the amorphous composite of IMC/SLD (1/1) was higher than that of the untreated IMC or SLD in the dissolution test. The permeated amounts and permeation rates of both drugs were enhanced by increasing the solubility of the amorphous composite. Conversely, the apparent membrane permeability coefficients (P) were almost same for untreated drugs and amorphous composites. In the case of hydroxypropyl-β-cyclodextrin and sodium dodecyl sulfate, P of the drugs decreased with the addition of these compounds, although the drug solubility was enhanced by the solubilization effect. This study revealed that an amorphous composite formed through hydrogen bonding is an attractive pharmaceutical way to enhance the permeated amount and permeation rate without changing the P of both the drugs.