Chemical Stability of the Botanical Drug Substance Crofelemer: A Model System for Comparative Characterization of Complex Mixture Drugs

Abstract

As the second of a 3-part series of articles in this issue concerning the development of a mathematical model for comparative characterization of complex mixture drugs using crofelemer (CF) as a model compound, this work focuses on the evaluation of the chemical stability profile of CF. CF is a biopolymer containing a mixture of proanthocyanidin oligomers which are primarily composed of gallocatechin with a small contribution from catechin. CF extracted from drug product was subjected to molecular weight-based fractionation and thiolysis. Temperature stress and metal-catalyzed oxidation were selected for accelerated and forced degradation studies. Stressed CF samples were size fractionated, thiolyzed, and analyzed with a combination of negative-ion electrospray ionization mass spectrometry (ESI-MS) and reversed-phase-HPLC with UV absorption and fluorescence detection. We further analyzed the chemical stability data sets for various CF samples generated from reversed-phase-HPLC-UV and ESI-MS using data-mining and machine learning approaches. In particular, calculations based on mutual information of over 800,000 data points in the ESI-MS analytical data set revealed specific CF cleavage and degradation products that were differentially generated under specific storage/degradation conditions, which were not initially identified using traditional analysis of the ESI-MS results.

Evidence to the role of interflavan linkages and galloylation of proanthocyanidins at sustaining long-term dentin biomodification

“…This mechanism could explain the observed drop in mechanical properties of the galloylated extracts, which seems to appear without negatively affecting the resistance to biodegradation of the biomodified tissue. Another reason could be the oxidative degradation of B-type PACs, resulting in the formation of higher molecular weight polymeric phlobaphenes or quinones [22,23], both of which no longer elicit the desired dentin cross-linking interactivity.…”

Comparative Characterization of Crofelemer Samples Using Data Mining and Machine Learning Approaches With Analytical Stability Data Sets

“…As described in detail in the 2 companion articles, 6,7 for the purpose of this study we dissolved surface-scraped Fulyzaq tablets in water and obtained purified crofelemer by centrifuging the mixture. We then fractionated the filtrate using molecular weight cutoff centrifugal filters.…”

“…A combination of absorption spectra, chromatography, and mass spec-trometry was used to monitor the CQAs of crofelemer, as described in the preceding 2 articles in this 3-article series. 6,7 CQAs are often used for comparisons between drug product batches. However, such comparisons often lack the capacity to deal with data sets of extreme size, or with the combination of orthogonal techniques to monitor a single CQA, which may be necessary to compare highly heterogeneous products.…”

“…It is used for treating noninfectious diarrhea in HIV/AIDS patients undergoing antiretroviral therapies. 12 As described in the companion articles in this series of 3 articles, 6,7 we prepared different samples of crofelemer by extracting it from the drug product tablet, dissolving it in aqueous solution, and then fractionating it. Finally, each sample was incubated at 2 different temperatures.…”

The Botanical Drug Substance Crofelemer as a Model System for Comparative Characterization of Complex Mixture Drugs

“…The analytical results from a variety of forced chemical degradation studies of crofelemer are presented in the second companion article. 18 In the third article 19 , a machine learning approach is applied to the entirety of this data set to identify which individual and/or combinations of assays which can distinguish between subtle variations in highly similar samples of crofelemer.…”