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.Piroksikam je nesteroidni protuupalni lijek male topljivosti u vodi koji ima svojstvo polimorfije. Cilj rada bio je priprema polimorfa piroksikama povećane topljivosti i brzine oslobađanja koristeći smjese različitih otapala i PEG 4000, odnosno PVP K30. Fizikokemijska svojstva modificiranih kristalnih oblika piroksikama ispitivana su difrakcijom X-zraka na praškastom uzorku FT-IR spektrofotometrijom i diferencijalnom pretražnom kalorimetrijom. Profili oslobađanja i topljivosti modificiranih kristalnih oblika proučavani su i uspoređivani sa čistim piroksikamom. Metodom uparavanja otapala (metoda I) dobiveni su igličasti i kubični kristali. Polaganom kristalizacijom iz etanola uz dodatak PEG 4000 ili PVP K30 na sobnoj temperaturi (metoda II) dobiveni su kubični kristali. Igličasti kristali dobiveni metodom I poboljšali su oslobađanje, ali ne i topljivost. Kubični kristali dobiveni metodom I imali su poboljšanu topljivost, ali sličan profil oslobađanja kao i netretirani piroksikam. Kubični kristali dobiveni metodom II imali su poboljšani profil oslobađanja, bez značajne promjene u topljivosti.
Na temelju XRPD rezultata, modificirani kristali piroksikama dobiveni metodom I iz smjese acetona i benzena bili su kubični, što dobro korelira s FTIR spektrom; modificirani igličasti kristali dobiveni iz smjese etanol/metanol i etanol/aceton imali su lagani pomak FTIR signala što bi se moglo pripisati razlikama u internoj strukturi ili konformacijama
