Formation, Characterization and In vitro Dissolution studies of Piroxicam-Malic Acid Cocrystals

Abstract

Piroxicam is one of the most potent anti-inflammatory non-steroidal drugs in the treatment of musculoskeletal, bone, and joint injuries including ankylosing spondylitis, osteoarthritis, and rheumatoid arthritis. Piroxicam exhibits poor solubility and slow onset of action in biological subjects. An oral dosage form of piroxicam with enhanced aqueous solubility is desired to enable a faster onset of action and its use for mild-to-medium-level acute pain relief. Cocrystal formation aims to increase piroxicam's solubility and the onset of action, thereby improving therapeutic effectiveness. Piroxicam-malic acid cocrystal is formed by solvent drop grinding method with methanol as a solvent. The preliminary characterization of piroxicam and cocrystal particles was determined by Scanning Electron Microscope, Differential Scanning Calorimetry, X-ray Diffractometry, and Fourier Transform Infra-Red Spectrophotometry to confirm the formation of hydrogen bonds. Dissolution studies of piroxicam and its cocrystals were performed in pH 1,2 hydrochloric acid solutions at 37°C. The microscopic analysis showed the formation of a new crystalline phase, and the thermal analysis showed a shift in the melting point to lower which confirms increased solubility due to the formation of the crystalline phase. Crystallographic analysis shows a new unique peak which indicates the formation of a new crystal lattice in the form of a triclinic lattice. This is also confirmed by the results of functional group analysis which shows the formation of heterosynthonic supramolecular hydrogen bonds between the amide group of piroxicam and the carboxylic group of malic acid. The greater dissolution rate is reached by piroxicam-malic acid (1:2) cocrystal.