Physical characterization of two oxyphenbutazone pseudopolymorphs

3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine, a new prodrug of zidovudine. Synthesis, solid state characterization, and anti HIV-1 activity

Synthesis, solid state characterization and anti HIV-1 activity of 3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine (2), a new prodrug of zidovudine (AZT, 1), are described. Two solid forms of 2 prepared by crystallization from ethyl acetate-petroleum ether (form alpha) and from a melt sample of form alpha (amorphous form) were characterized by X-ray diffractometry, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA) techniques. The novel nucleoside exhibited antiviral activity against standard and resistant strain panels of HIV-1 as well as cytotoxicity similar to that of AZT.

Solid phases of tenoxicam

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.

Polymorphism of sulindac: isolation and characterization of a new polymorph and three new solvates

The polymorphism of sulindac was investigated. Two polymorphs (I and II) and a new crystalline form (form III) of sulindac were prepared by recrystallization in different solvents. In addition, three new pseudopolymorphs (solvates) from acetone, chloroform, and benzene were obtained, with each containing 1 mol of solvent to 2 mol of sulindac. Different sulindac polymorphs and pseudopolymorphs were characterized by X-ray diffractometry, infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and hot-stage microscopy. The transition behavior of the crystalline forms of sulindac, their melting points, and their enthalpies were investigated by DSC. The melting of form II was observed at 184 degrees C, and form I subsequently recrystallized from this melt. Similarly, form III melts at 145 degrees C and then recrystallizes to form I. We also investigated the influence of the crystallization solvent on sulindac crystal shape.

High-resolution solid-state carbon-13 nuclear magnetic resonance spectra of mofebutazone, phenylbutazone, and oxyphenbutazone in relation to X-ray crystallographic data

The solid-state 13C NMR spectra of mofebutazone, phenylbutazone, and oxyphenbutazone monohydrate and anhydrate are presented. The crystal structures of these pyrazolidinedione derivatives, obtained by single-crystal X-ray analysis, were previously reported, revealing distinct differences in crystal structure. In this report, the chemical shift values observed for the solid-state 13C spectra are related to the chemical environment of the various carbon atoms and compared with the crystallographic data. Results indicate that solid-state NMR spectroscopy is potentially useful in the study of drugs in the solid state.