title: Piroxicam benzoate--synthesis, HPLC determination, and hydrolysis.
abstract: An improved method of piroxicam benzoate synthesis was described, and an isocratic reversed-phase high-performance liquid chromatography method for its determination was developed and fully validated. The method was found to be specific, precise (relative standard deviation 0.3%), accurate (mean recovery 99.9%), and robust. Limit of detection was estimated at 0.055 microg mL(-1) and limit of quantification at 0.185 microg mL(-1). The kinetics of piroxicam benzoate hydrolysis in aqueous buffer solutions (pH 1.1 and 10), simulated gastric and intestinal fluids was studied. The hydrolysis followed first-order kinetics. The following rate constants were obtained at pH 10: k = 1.8 x 10(-3) hr(-1) at 37 degrees C and k = 3.4 x 10(-2) hr(-1) at 60 degrees C. In acidic media, no significant hydrolysis was observed after 24 hr. During the 24-hr period in simulated intestinal fluid, only 10.9% of the starting ester was hydrolyzed.
authors.affiliation: Center for Quality Assurance of Medicines, Potchefstroom University, Potchefstroom, South Africa. fmsbb@puknet.puk.ac.za
authors.forename: Barend
authors.initials: B
authors.lastname: Boneschans
authors.forename: Anita
authors.initials: A
authors.lastname: Wessels
authors.forename: Johan
authors.initials: J
authors.lastname: van Staden
authors.forename: Marijana
authors.initials: M
authors.lastname: Zovko
authors.forename: Branka
authors.initials: B
authors.lastname: Zorc
authors.forename: Jacobus
authors.initials: J
authors.lastname: Bergh
mesh_terms: D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D006868:Hydrolysis; D007700:Kinetics; D019999:Pharmaceutical Solutions; D010894:Piroxicam / Q000031:analogs & derivatives / Q000032:analysis / Q000138:chemical synthesis* / Q000737:chemistry; D011208:Powders; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012995:Solubility; D013997:Time Factors
chemical_list: D001565:Benzoates; D002021:Buffers; D019999:Pharmaceutical Solutions; D011208:Powders; C477988:piroxicam benzoate; D010894:Piroxicam