| Περίληψη: | <span style="font-variant: small-caps;">d</span>-cycloserine is a broad-spectrum antibiotic that is currently being used as a secondary choice in the treatment of tuberculosis. In recent years, it has become more popular, due to its effect on the nervous system. In this current study, we provide evidence that The International Pharmacopoeia HPLC–UV method for <span style="font-variant: small-caps;">d</span>-cycloserine impurity profiling is not repeatable due to the variable response of cycloserine dimer, one of <span style="font-variant: small-caps;">d</span>-cycloserine impurities. Therefore, we introduced the DOSY (diffusion ordered spectroscopy) NMR (nuclear magnetic resonance) technique to determine the levels of <span style="font-variant: small-caps;">d</span>-cycloserine impurities in pharmaceutical dosage forms. The DOSY NMR technique allowed separation of <span style="font-variant: small-caps;">d</span>-cycloserine, its degradation products, and key process impurities in concentrations below pharmacopoeial specification limits. The proposed DOSY NMR method allowed accurate identification and quantification of the cycloserine dimer, which was not possible through the use of the pharmacopoeial HPLC method. The current method has the potential for practical use in analytical laboratories of the pharmaceutical industry.
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