title: Insight into the solubility and dissolution behavior of piroxicam anhydrate and monohydrate forms.
abstract: The aim of the present study was two-fold: (1) to investigate the effect of pH and presence of surfactant sodium lauryl sulphate (SLS) on the solubility and dissolution rate of two solid-state forms of piroxicam (PRX), anhydrate (PRXAH) and monohydrate (PRXMH), and (2) to quantitatively assess the solid-phase transformation of PRXAH to PRXMH in slurry with a special interest to the impact on the solubility and dissolution behavior of the drug. X-ray powder diffractometry (XRPD), Raman spectroscopy and scanning electron microscopy (SEM) were used for characterization of the solid-state forms. Phase transformation was monitored in slurry by means of in-line Raman spectroscopy, and the partial least squares (PLS) regression model was used for predicting the amount of PRXMH. The results showed that the solubility and dissolution rate of PRXAH were higher compared to PRXMH at different pHs. The pH and presence of SLS together affected the solubility and dissolution rate of different PRX forms. The lowest solubility values and dissolution rates for PRX forms were observed in distilled water (pH 5.6) at 37 °C. The changes in the dissolution rate could be explained by the hydrate formation during solubility testing. The rate of hydrate formation was also dependent on the pH of the dissolution medium.
authors.affiliation: Department of Pharmacy, Faculty of Medicine, University of Tartu, Nooruse 1, 50411 Tartu, Estonia. urve.paaver@ut.ee
authors.forename: Urve
authors.initials: U
authors.lastname: Paaver
authors.forename: Andres
authors.initials: A
authors.lastname: Lust
authors.forename: Sabiruddin
authors.initials: S
authors.lastname: Mirza
authors.forename: Jukka
authors.initials: J
authors.lastname: Rantanen
authors.forename: Peep
authors.initials: P
authors.lastname: Veski
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heinämäki
authors.forename: Karin
authors.initials: K
authors.lastname: Kogermann
mesh_terms: D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010894:Piroxicam / Q000737:chemistry*; D033362:Powder Diffraction; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012995:Solubility; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D010894:Piroxicam; D012967:Sodium Dodecyl Sulfate