Acta Pharm. 53 (2003) 165-173

Solid-state investigation of piroxicam benzoate

BISERKA CETINA-CIZMEK,^1,4* MARIJAN TUDJA,³ ERNEST MESTROVIC², MARIJANA ZOVKO,¹ BRANKA ZORC¹ and PETAR TUDJA⁴

biserka.cetina-cizmek@pliva.hr

¹Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia
²Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
³Quality Assurance Department, PLIVA Inc., 10000 Zagreb, Croatia
⁴Research and Development Department, PLIVA Inc., 10000 Zagreb, Croatia

Solid-state properties of piroxicam benzoate, an ester prodrug of piroxicam, were investigated. Samples were prepared by recrystallization from various organic solvents (toluene, ethanol, methanol, ethyl acetate and acetone). Recrystallized samples were characterized by means of FTIR, DSC, TGA, SEM and XRPD. DSC, TGA and XRPD methods confirmed that piroxicam benzoate crystallized in two pseudopolymorphic forms, A and B. Pseudopolymorphic form A was obtained by recrystallization from ethanol and methanol by slow cooling at room temperature and by rapid cooling in an ice-cold bath, and also from toluene by rapid cooling in an ice-cold bath. Pseudopolymorphic form B was obtained by recrystallization from toluene by slow cooling at room temperature.

Keywords: piroxicam benzoate, pseudopolymorphism, FTIR, thermal analysis, XRPD, SEM