The necessity of healthcare supply chain resilience for crisis preparedness.

Prior to and during the COVID-19 pandemic, Canadian provincial health systems and governments did not sufficiently consider healthcare supply chain in their crisis preparedness plans, leading to an exposed and vulnerable healthcare system. There have been many opportunities to learn from past Canadian and global crises, which have emphasized the importance of healthcare supply chain resilience in providing essential care to patients; however, considerations of healthcare supply chain resilience remain a significant gap in preparedness planning. Illustrated through the Canadian response to COVID-19 pandemic, this article will explore how healthcare supply chain resilience should be a necessary consideration in any crisis preparedness plans. Further, without this consideration of healthcare supply chain resilience, it is the person (the patient and healthcare worker), and especially vulnerable populations, that are most put at risk in the event of a future crisis.

Mathematical Relationships of Individual Stereocenter er Values to dr Values.

A mathematical relationship is derived for relating the enantiomeric ratios (er values) of two individual stereocenters within a single chiral molecule to the diastereomeric ratio (dr). Whereas the er (or enantiomeric excess, ee) of chiral molecules is readily determined by chiral chromatography and dr values can be determined by chromatography or NMR, modern methods for the optical determination of er values at individual functional groups do not normally determine the er and dr of the entire molecule. We find there is only a special circumstance when knowledge of the er of two individual stereocenters can be used to predict the er of the enantiomers in each diastereomeric set, along with the dr of the stereoisomers. Under circumstances where this relationship fails, one will require a dr assay in addition to two individual er assays to fully characterize the stereochemical parameters of a reaction. Thus, with these circumstances in mind, we give mathematical relationships for determining complete stereoisomer speciation having the knowledge of individual stereocenter er values and a dr value.