Estimation of impurity profiles of drugs and related materials Part 15. Identification of minor impurities in cimetidine

The Role of Analytical Chemistry in the Safety of Drug Therapy

“…In this case, the PDA-UV spectra were not informative. From these data it is evident that impurity A contains two identical side chains that originate from an overreaction, the addition of a second formaldehyde C-NMR data [217]. From these data it is evident that impurity A contains two identical side chains that originate from an overreaction, the addition of a second formaldehyde C-NMR data [217].…”

“…The aim of another study was the structure elucidation of two unknown, apolar, minor impurities in cimetidine [217] eluting at relative retention time of 2.9 (impurity FIGURE 8.7 PDA-UV spectra of ethinylestradiol and its impurity 9(11)-dehydroethinylestradiol [216].…”

Determination of organic impurities in pharmaceutical preparations

“…Commonly, NMR is used to obtain and confirm data on the structure of molecular fragments formed in MS. In some cases, only the combination of NMR and MS gives the full information on the structure of the studied component [50,72,82,84,90]. NMR spectrometry also allows the quantitative determination of impurities; however, its low sensitivity and poor reproducibility are substantial limitations of the method.…”

“…In some cases, impurities are identified using the chromatographic extraction of fractions containing impurities, their preconcentration with solvent replacement, and the subsequent measurement of mass spectra [50,72,90] and NMR spectra [50,60,72,80].…”

A critical review on the use of modern sophisticated hyphenated tools in the characterization of impurities and degradation products

“…The subject matter has been the content of many articles and book chapters that include excellent case studies [46,52,[60][61][62][63][64][65]. There are series of papers by Görög et al involving characterization of IMPs of a number of drug molecules [66][67][68][69]. Baertschi et al reported degradation behavior of cefaclor in multiple papers [70][71][72], highlighting the use of conventional approach in the characterization of almost 30 DPs of the drug.…”