Recent applications of analytical techniques for quantitative pharmaceutical analysis: A review

The intension of this paper was to review and discuss some of the current quantitative analytical procedures which are used for quality control of pharmaceutical products. The selected papers were organized according to the analytical technique employed. Several techniques like ultraviolet/visible spectrophotometry, fluorimetry, titrimetry, electroanalytical techniques, chromatographic methods (thin-layer chromatography, gas chromatography and high-performance liquid chromatography), capillary electrophoresis and vibrational spectroscopies are the main techniques that have been used for the quantitative analysis of pharmaceutical compounds. In conclusion, although simple techniques such as UV/VIS spectrophotometry and TLC are still extensively employed, HPLC is the most popular instrumental technique used for the analysis of pharmaceuticals. Besides, a review of recent works in the area of pharmaceutical analysis showed a trend in the application of techniques increasingly rapid such as ultra performance liquid chromatography and the use of sensitive and specific detectors as mass spectrometers.

Analysis of agonist and antagonist effects on thyroid hormone receptor conformation by hydrogen/deuterium exchange

Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains important to understand apo-LBD conformation and the way that it rearranges with ligands to develop better TR pharmaceuticals. In this study, we conducted hydrogen/deuterium exchange on TR LBDs with or without agonist (T 3) or antagonist (NH3). Both ligands reduce deuterium incorporation into LBD amide hydrogens, implying tighter overall folding of the domain. As predicted, mass spectroscopic analysis of individual proteolytic peptides after hydrogen/ deuterium exchange reveals that ligand increases the degree of solvent protection of regions close to the buried ligand-binding pocket. However, there is also extensive ligand protection of other regions, including the dimer surface at H10-H11, providing evidence for allosteric communication between the ligand-binding pocket and distant interaction surfaces. Surprisingly, Cterminal activation helix H12, which is known to alter position with ligand, remains relatively protected from solvent in all conditions suggesting that it is packed against the LBD irrespective of the presence or type of ligand. T 3, but not NH3, increases accessibility of the upper part of H3-H5 to solvent, and we propose that TR H12 interacts with this region in apo-TR and that this interaction is blocked by T 3 but not NH3.Wepresent data from site-directed mutagenesis experiments and molecular dynamics simulations that lend support to this structural model of apo-TR and its ligand-dependent conformational changes. (Molecular Endocrinology 25: 15-31, 2011). Copyright © 2011 by The Endocrine Society.

A simple and environmentally friendly reflectometric method for the rapid quantitative analysis of captopril in pharmaceutical formulations

This paper describes a simple, environmentally friendly and rapid quantitative spot test procedure for the determination of captopril (CPT) in bulk drug and in pharmaceutical formulations by using diffuse reflectance spectroscopy. The proposed method is based on the reflectance measurements of the orange compound (λ max 490 nm) produced by the spot test reaction between CPT and p-chloranil (CL). Under optimal conditions, calibration curves were obtained for CPT by plotting the optical density of the reflectance signal (A R) vs. the log of the mol L -1 concentration, from 6.91×10 -3 to 1.17×10 -1, with a good coefficient of determination (R 2 = 0.9992). The common excipients used as additives in pharmaceuticals do not interfere in the proposed method. The method was applied to determine CPT in commercial pharmaceutical formulations. The results obtained by the proposed method are compared favorably with those obtained by an official procedure at 95% confidence level. The method validation results showed that the sensitivity and selectivity of the methods were adequated for drug monitoring in industrial quality control laboratories. © 2011 Moment Publication.

Sensitive flow-injection spectrophotometric analysis of bromopride

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