Pharmacokinetic (PK) parameters of new drug candidates are traditionally determined by measuring drug concentration in plasma. However, many compounds bind to or diffuse into red blood cells (RBCs), and considering RBCs comprise at least 99% of cellular space in blood, this can significantly impact clearance and cause inaccuracies in PK calculations.

That’s why the majority of polled researchers said that they regularly conduct Red Blood Cell Partitioning Studies. Evaluating potential drug sequestration in red blood cells in addition to plasma protein binding studies helps to prevent misinterpretation of pharmacokinetic data and the potential overestimation of a drug’s intrinsic clearance. In fact, the majority of polled researchers said they run the studies just to be thorough, with the 2nd most common reason being indicators based on the molecular properties of their compound. The vast majority of respondents also said that they perform these evaluations in the discovery/preclinical phase of development, which helps to avoid costly missteps and delays from having to run additional studies because of clinical results or requests from a regulatory agency.