ABSTRACT
The anti-inflammatory drug indomethacin was investigated regarding new related impurities. Therefore, related substances 2-9 were prepared by independent synthesis and physicochemically characterized. To determine indomethacin and its related substances, a new HPLC-UV method was developed and validated. Indomethacin and its impurities were eluted on a C(18) column with a mobile phase consisting of methanol and an aqueous solution of 0.2% phosphoric acid at a flow rate of 1.5 ml/min and were quantified by UV detection at 320 nm. Overall, the HPLC-UV method was simple and reliable for the detection of eight impurities in indomethacin. In addition to the HPLC-UV method, 1H nuclear magnetic resonance (NMR) was used to investigate indomethacin regarding impurities. For that purpose, related substances 2-9 were systematically added to indomethacin and investigated. The NMR method was found to be very useful for the identification of impurities in bulk substance without prior separation. Both HPLC-UV and NMR were used to analyze 38 batches of indomethacin available on the European market. The outcome was that 42% of the batches did not meet the compendial requirements although they met the specifications of current compendial methods. Some batches contained the previously undescribed impurity 8, while other batches contained by-products from two distinct synthetic routes. The methods presented herein are important contributions to the ongoing efforts to reduce impurities and therefore the risk of adverse side-effects in drugs that are no longer under patent protection.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/analysis , Anti-Inflammatory Agents, Non-Steroidal/isolation & purification , Indomethacin/analysis , Indomethacin/isolation & purification , Chromatography, High Pressure Liquid/standards , Indomethacin/chemical synthesis , Nuclear Magnetic Resonance, Biomolecular/methods , Protons , Reproducibility of Results , Spectrophotometry, Ultraviolet/standardsABSTRACT
The analysis of several impurities of the chemotherapeutic agent trimethoprim with various methods, including thin layer chromatography, gas chromatography, capillary electrophoresis as well as nuclear magnetic resonance is described. These methods were used to identify new impurities in trimethoprim batches. The main impurities were separated by column chromatography. To ensure the identity of the impurities, de novo syntheses were successfully carried out. With the methods described, it was possible to detect, separate and identify new impurities in trimethoprim batches.
Subject(s)
Anti-Infective Agents, Urinary/chemistry , Drug Contamination , Trimethoprim/chemistry , Chromatography, High Pressure Liquid , Chromatography, Thin Layer , Electrochemistry , Electrophoresis, Capillary , Gas Chromatography-Mass Spectrometry , Indicators and Reagents , Magnetic Resonance SpectroscopyABSTRACT
The synthesis of 5'-substituted thalidomide analogs is described. The amino acids 2 necessary to synthesize the target compounds were prepared by Michael reaction. Condensation of 2 with phthalic anhydrides followed by reaction with urea yielded 4 as diastereomeric mixtures. Furthermore glutethimide (5) was brominated by an improved method and the resulting compound 6 was reacted in several steps with sodium azide, hydrogen, and phthalic anhydride to give 8. In a similar manner, 6 was reacted with sodium azide and various phthalic anhydrides to give 9, 10, and 11. All final compounds were tested in vitro for their inhibitory activity on the release of TNF-alpha, using stimulated peripheral mononuclear blood cells (PBMCs). Compounds with an additional aromatic substituent in position 5' of the thalidomide molecule were more active than thalidomide. Compound 11 was able to reduce increased levels of IL-2 in vitro.
