Acikgöz and colleagues exposed cultured primary human and pig hepatocytes to diazepam. They separately analyzed the cell material and the liquid above the cells. That design allowed them to compare what remained in the cellular compartment with what appeared in the surrounding medium.
Desmethyldiazepam, temazepam and oxazepam were detected in both compartments at points during the experiment. The human cells were sampled at six times over 24 hours. A measurement in the medium reflects what reached the sampled liquid. The cell measurement supplies information about a compartment that would otherwise have been left out.
The experiment illustrates why an assay’s sampling location matters when interpreting a metabolic profile. Culture medium is a controlled laboratory environment. Human blood concentrations also reflect distribution, ongoing metabolism and elimination. The experiment cannot establish dose or time since ingestion from a case specimen.
Acikgöz et al., International Journal of Nanomedicine (2012) · Full text