No abstract

Nifenazone (1,5-dimethyl-4-nicotinamido-2-phenyl-3pyrazolone) (Fig. 1) is a pyrazole drug that was expected to be used in the treatment of a variety of rheumatic disorders. Unfortunately, it was proved that the drug is not of significant value for chronic rheumatic disorders. 1 The compound, however, has a unique drug-like structure, and is often included as a member of chemical libraries for drug discovery. An X-ray analysis of the title compound was undertaken to disclose its inherent three-dimensional structure, which is indispensable for drug design.

Carisoprodol (1-methylethyl)carbamic acid 2-[[(aminocarbonyl)oxy]methyl]-2-methylpentyl ester) produces muscle relaxation in animals by blocking interneuronal activity in the descending reticular formation and spinal cord. 1 The onset of action is rapid and effects last four to six hours. The molecule is indicated as an adjunct to relieve discomfort associated with acute and painful musculoskeletal conditions. The mode of action of the molecule has not been clearly identified. The X-ray analysis of the title compound was undertaken to disclose its inherent three-dimensional structure to understand the molecular mechanism of the drug action. The chemical structure is shown in Fig. 1. Platelet single crystals were grown from acetone solution. A colorless crystal with the size of 0.1 × 0.1 × 0.1 mm was mounted on a glass fiber and used for data collection. The structure was solved by direct methods and refined by fullmatrix least squares method. Non-hydrogen atoms were refined with anisotropic temperature factors. All H-atoms except those of the methylethyl group were located by difference Fourier synthesis and they were refined with isotropic temperature factors. The hydrogen atoms of the methylethyl group were calculated geometrically and fixed through the refinement. The crystal and experimental data are shown in Table 1. Atomic parameters of non-H atoms are shown in Table 2.