Identification of reaction products between drug substances and excipients by HPLC–SPE–NMR: Ester and amide formation between citric acid and 5-aminosalicylic acid

Evaluation of microwave oven heating for prediction of drug–excipient compatibilities and accelerated stability studies

“…1) were different regarding physico-chemical properties, e.g., partition coefficient and ionization properties, but all contained either carboxylic acid or amine functionalities capable of participating in ester or amide formation. Examples of the formation of ester and amide reaction products in relation to stability and drug-excipient compatibility testing have been published (Kochling et al, 2007;Larsen et al, 2009aLarsen et al, , 2009bPoole et al, 2011), but systematic investigations have not been performed regarding the relative reactivity of commonly employed excipients.…”

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

“…More specific applications of 1D and 2D LC-NMR in understanding inherent degradation behavior of APIs and the formation of DPs in formulations were critically described by Pan et al [103]. There are several other reports on the use of LC-NMR for structural characterization of IMPs and degradation/interaction products [39,122,153,168,[225][226][227][228][229][230][231][232][233][234][235][236][237][238][239][240][241][242]. A compilation is separately given in Table S4, which includes details of drugs/compounds investigated, IMPs/DPs characterized, their amount in the sample, instrument configuration, operation mode, etc.…”

Rapid Identification of Bioactive Carbohydrazide Reaction Products by an LC-DAD-SPE-NMR Approach

“…LC-SPE-NMR is now widely accepted tool for dereplication and discovery of natural products from complex mixtures of plants, metabolites, drug impurity profiling and environmental analysis [17][18][19][20][21]. On the other hand, it has been less frequently used to monitor chemical reaction products [22,23]. Hence, in the present work we applied this hyphenated method to analyse carbohydrazide condensation reaction.…”