Investigation of unknown impurities of paromomycin in a 15% topical cream by liquid chromatography combined with mass spectrometry

Abstract

Rationale Characterization of unknown impurities in degraded paromomycin 15% topical cream samples by ultra‐high‐performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) gas‐phase fragmentation is described. Methods A volatile reversed‐phase high‐performance liquid chromatography/charged aerosol detection (RP‐HPLC/CAD) method was developed and validated for fast and consistent analysis of the paromomycin potency and impurity values in drug substance and drug product samples. A Veo charged aerosol detector was chosen for routine analysis. The method shows separation of two paromomycin isomers as well as twelve unknown impurity peaks. The identity of the unknown impurities was investigated by LC/MS/MS using a quadrupole time‐of‐flight (QTOF) mass spectrometer. Results Six of the HPLC/CAD impurity peaks met the ICH Q3B(R2) threshold for identification and were investigated by coupling the developed LC method with a QTOF instrument. Structures for the impurities were proposed based on gas‐phase fragmentation patterns of the paromomycin reference standard. Impurity fragmentation pathways were proposed based on literature of other structurally related aminoglycoside compounds. Conclusions Nine unknown paromomycin impurities were identified and the observed modifications included acetylation, carbamylation, gain of a hexose, and loss of glucosamine. The most abundant paromomycin modification was carbamylation by urea (a cream excipient) characterized by a 43 Da mass increase.

Research progress on the impurities identification and determination in pharmaceuticals

“…Zhu et al 70 used LC-MS to study the fragmentation patterns of impurities in sodium drug substance and eye drops, deduced the chemical structures of impurities, confirmed the structure with 1D and 2D NMR data, and achieved the structures characterization of 2 unknown impurities and 6 unknown degradation products and a plausible mechanism for the formation of the degradation products was also proposed. Hertzler et al 71 study fragmentation patterns and fragmentation pathways of paromomycin impurities based on UHPLC/MS/MS and the literature of other structurally related aminoglycoside compounds, and made reasonable suggestions for the storage methods of drugs.…”

Highly sensitive liquid chromatographic method combined with online ion suppression to remove interfering anions and mass spectrometry for impurity profiling of paromomycin sulfate

“…Hertzler et al. [27] developed and validated a volatile reversed‐phase HPLC‐CAD method that identified nine PRM impurities. Modifications such as acetylation, carbamylation, addition of hexose and loss of glucosamine were observed.…”

“…Given that PRM and its impurities have similar structures without UV-absorbing chromophores, decent detection techniques should be applied, and few LC-based methods for detecting PRM in human biological matrices have been reported [23][24][25][26]. Hertzler et al [27] developed and validated a volatile reversed-phase HPLC-CAD method that identified nine PRM impurities. Modifications such as acetylation, carbamylation, addition of hexose and loss of glucosamine were observed.…”