Search

The composites of piroxicam and meloxicam with gamma-alumina, aluminium hydroxides (gibbsite and boehmite), alpha and gamma polymorphs of iron(III) oxide having different surface area and morphology were prepared by planetary ball-milling. It has been shown that the initial state of the excipient (specific surface area, particle size and morphology) had a pronounced effect on the formation of the core-shell composites with the drugs and their properties. The X-ray diffraction patterns and IR spectra measured for co-milled samples as well as X-ray photoelectron spectroscopy studies gave evidence that the components of the mixtures interacted with each other and became amorphous, as composites were formed. The drug release from the composites was different as compared with pure drugs, meloxicam and piroxicam behaving differently that can be explained by formation of strong or weak bonds with the active sites of the carriers. In the case of mechanocomposites, the drugs dissolved quickly due to high surface of organic phase in the core-shell composites. The high-porous carriers can serve as the sorbents for the drugs in solution. [ABSTRACT FROM AUTHOR]

The nanocomposites of piroxicam and meloxicam with alumina were obtained by ball-milling as a result of distribution of the drugs at the surface of oxide with formation of the stable composites. The observed changes in the IR spectra of the ball-milled mixtures suggested the interaction of the drugs with the alumina active surface sites. The functional groups in molecules of piroxicam and meloxicam involved into formation of bonds between the drugs and the surface of the oxide were determined, they are amide, sulfate, enol groups, and pyridyl / thiazolyl nitrogen atoms. It appears that the formation of the new bonds at the contacts of particles in the composite leads to the stabilization of the drugs in metastable state inhibiting their transformation into initial crystalline form. [ABSTRACT FROM AUTHOR]