Enhancement of dissolution rate and anti-inflammatory effects of piroxicam using solvent deposition technique

Piroxicam solid depositions were prepared by means of the solvent deposition technique using different concentrations of microcrystalline cellulose as carrier material. The solvent deposition system (SDS) with drug to carrier ratio of 1:9 had a rapid dissolution rate in vitro. When this SDS was administered perorally to rats with a previous experimentally induced inflammation in their paws, it exhibited a pronounced anti-inflammatory action. X-ray diffraction and infrared (IR) spectroscopy showed no differences in the crystal state of piroxicam in SDS formulation and physical mixture of piroxicam and carrier. The increase in the dissolution rate and consequent enhancement of anti-inflammatory effect of piroxicam in SDS were attributed to the reduced particle size of drug deposited on the carrier and enhanced wettability of the particles brought about by the carrier.

Characterisation and theoretical investigation of the electronic properties and second-order nonlinearity of some three dentate salicylaldiminato Schiff base ligands

A series of asymmetric three dentate salicylaldiminato Schiff base ligands 1-4 (Scheme 1) has been synthesized and their structures, electronic properties and second order nonlinearities are investigated using the AM1 Hamiltonian SCF-MO methods. The analysis of MOs indicates that the O(2) atom could be the coordination site if the ligands were monodentate. In addition, the atomic orbitals on the O(9) atom have no contributions to the frontier MOs of the anionic form of these three dentate ligands. The Mulliken populations reveal that the coordination sites N(6) and O(9) possess different character in generation of the Schiff base complexes. The molecular first-order hyperpolarizability value of ligands was calculated using finite field method. Generally the presence of the methoxy group as third dentate play a major role in increasing the second harmonic generation (SHG) responses of three dentate ligands. Comparison of the NLO properties of two dentate with three dentate salicylaldiminine-based ligands reveals that the presence of -NO2 and -OCH3 groups as R1 and R2 substituents enhance the second-order nonlinear optic properties of these type ligands.