Acta Pharm. 61 (2011) 391-402

 

full paper

Original research paper

 

Crystal modifications and dissolution rate of piroxicam

LIM YEE LYN, HUAN WEN SZE, ADHIYAMAN RAJENDRAN, GORAJANA ADINARAYANA, KAMAL DUA and SANJAY GARG

adinarayana_gorajana@imu.edu.my

1 School of Pharmacy and Health Sciences, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia

2 AnQual Laboratories, School of Pharmacy, University of Auckland, Auckland, New Zealand

 

Accepted October 18, 2011

 

Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced bothneedle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

Keywords: piroxicam, polymorphism, crystallization, polymer, dissolution