[Simple method for quantitative determination of active polymorphous and amorphous drugs in drug products by fourier transform-Raman spectroscopy].

The feasibility of a simple Fourier transform (FT)-Raman spectroscopic method for the quantitative determination of unexpected active drug polymorphs or amorphous in drug products was explored. In this study, calibration samples were prepared by physically mixing drug substances with their polymorphs or amorphous, without using excipients. A partial least-squares (PLS) method was applied to the quantitative analysis of the FT-Raman spectra obtained.

Matrix media selection for the determination of residual solvents in pharmaceuticals by static headspace gas chromatography.

The influence of the matrix medium used for the determination of residual solvents in pharmaceuticals by static headspace gas chromatography was investigated. The purpose of this paper is to propose a guide for the choice of a matrix medium suitable for the determination of residual solvents of interest. Dimethylsulfoxide (DMSO), N,N-dimethyformamide (DMF), N,N-dimethylacetamide (DMA), benzyl alcohol (BA), 1,3-dimethyl-2-imidazolidinone (DMI) and water were studied as matrix media, and seventeen solvents used for the synthesis and purification of drug substances were used as target analytes.

Investigation of intermolecular interaction in molecular complex of tryptamine and benzoic acid by solid-state 2D NMR.

Solid-state NMR spectra and powder X-ray diffraction of the two-component molecular complex composed of tryptamine and benzoic acid were observed to investigate the intermolecular interaction in the molecular complex. 1D (13)C CP/MAS NMR spectrum and powder X-ray diffraction pattern of the complex was clearly different from the convolution of each spectrum of the single component. 2D (1)H-(13)C heteronuclear-correlation (HETCOR) NMR technique indicated that the intermolecular interaction between the primary amine of tryptamine and the carboxyl group of benzoic acid must be related to the complex formation.

A novel method for estimation of transition temperature for polymorphic pairs in pharmaceuticals using heat of solution and solubility data.

A novel method for thermodynamic stability studies of polymorphic drug substances has been developed. In order to estimate the transition temperature for an enantiotropic polymorphic pair, a formula for calculating the temperature at which the solubilities of each polymorph become equal has been derived with heat of solution and solubility as the variables. This formula is based on the assumption that van't Hoff plots (logarithmic solubility versus reciprocal of absolute temperature plots) of each polymorph show a straight line (heat of solution is independent of temperature) whose slope can be expressed as a function of heat of solution.