mobiflex and acetonitrile

A simple cloud-point extraction method for the determination of meloxicam in human serum was developed. Meloxicam was extracted from serum sample after adding 1 mL of 3% (v/v) Triton X-114 aqueous solution in the presence of 1M HCl and 60 mg NaCl. The meloxicam, present in the surfactant-rich phase, was enriched again with acetonitrile. Tenoxicam was used as the external standard. The separation was achieved on a C18 analytical column with a mobile phase consisting of aqueous acetic acid (1%, v/v) and acetonitrile (54:46, v/v). UV detection was performed at 360 nm. The response was linear over the range 45-2000 ng mL(-1) in human serum, and intra- and interday precisions of less than 15.0% were obtained. The relative error was within +/-3.0%. The recoveries of meloxicam were larger than 92.0%. The method was compared with liquid-liquid extraction. The results showed that the new method has a considerable LOQ and higher recoveries but poorer precision than liquid-liquid extraction, which exhibited poor recoveries of less than 86.0%, precisions of less than 5.0% and relative errors of less than 7.0%. The method was used for the determination of meloxicam in healthy human volunteers.

Topics: Acetic Acid; Acetonitriles; Adult; Anti-Inflammatory Agents, Non-Steroidal; Chromatography, High Pressure Liquid; Detergents; Drug Stability; Humans; Meloxicam; Piroxicam; Polyethylene Glycols; Reproducibility of Results; Sensitivity and Specificity; Solvents; Thiazines; Thiazoles

In this report we describe the preparation and characterization of four polymorphic forms of tenoxicam; they are, three 1:1 stoichiometric solvates with acetonitrile, dioxane, and N,N-dimethylformamide, and an amorphous phase obtained by recrystallization in various solvents. Polymorph IV and solvates with dioxane and N,N-dimethylformamide are reported for the first time in this paper. In addition, three solvates were crystallized in acetone, ethyl acetate, and isopropyl alcohol. These solid forms were characterized by X-ray powder diffraction, differential scanning calorimetry, infrared spectroscopy, thermogravimetry, optical microscopy, and elemental analysis. Solid-state properties, intrinsic dissolution rate, and dissolution kinetics from formulated tablets are also provided.

Topics: 1-Butanol; 2-Propanol; Acetamides; Acetates; Acetone; Acetonitriles; Benzene; Calorimetry, Differential Scanning; Chemical Phenomena; Chemistry, Physical; Chloroform; Crystallography, X-Ray; Dimethylformamide; Dioxanes; Hydrogen-Ion Concentration; Kinetics; Piroxicam; Solubility; Solvents; Spectrophotometry, Infrared; Spectrophotometry, Ultraviolet

The products of recrystallization of tenoxicam (4-hydroxy-2-methyl-N-2-pyridinyl-2H-thieno[2,3-e]-1,2-thiazine-3- carboxamide 1,1-dioxide) from ethanol and acetonitrile were investigated by thermogravimetric analysis, differential scanning calorimetry, and X-ray diffraction. Recrystallization from ethanol yielded a polymorph designated 1, and recrystallization from acetonitrile gave a solvate 2 with 1:1 stoichiometry. The structures of 1 and 2 were determined by single-crystal X-ray methods. Polymorph 1 is triclinic, space group P1, with Z = 4; solvate 2 is monoclinic, space group P2(1)/n, with Z = 4. In both crystal structures, the tenoxicam molecule exists in the zwitterionic form, adopting a planar conformation that is stabilized by two intramolecular hydrogen bonds (N(+)-H...O and N-H...O-). Tenoxicam molecules associate by N(+)-H...O and C-H...N hydrogen bonding in both crystal structures. Desolvation of 2 yields a polymorph of tenoxicam that is different from polymorph 1. A study of the kinetics of the desolvation of 2 by dynamic thermogravimetry yielded estimates of the activation energy in the range 69-72 kJ.mol-1. From a comparison of experimental and simulated X-ray powder diffraction patterns, neither 1 nor 2 undergoes a polymorphic transition upon grinding. X-ray patterns based on the single-crystal X-ray data for 1 and 2 are presented as reliable references for their identification.

Topics: Acetonitriles; Anti-Inflammatory Agents, Non-Steroidal; Ethanol; Molecular Structure; Piroxicam; Temperature; Thermogravimetry; X-Rays