Sampling Time in Pharmacokinetics. Getting it right, matters.

Pharmacokinetics is the mathematical characterization of the time course of drug absorption, distribution, metabolism, and excretion from the body.

The underlying aim of starting such a discovery process is typically to determine the basic concentration-time curve on which the maximal concentration of a tested analyte (Cmax) at the equivalent time (Tmax) can be read, together with the description of how quickly the levels go up, how long they stay for, and how quickly they fall.

The design of the sampling times, therefore, plays a critical role in the reliability of the bioequivalence evaluation, as does ensuring that enough samples to adequately describe the plasma concentration-time profile are collected throughout the test.

As such, the sampling schedule should be frequent enough based on the predicted Tmax (time of maximal plasma concentration) to provide a reliable estimate of peak exposure to the subjects, while also covering the plasma concentration-time curve long enough to provide a reliable estimate of the extent of exposure.

This is achieved if AUC(0–t) (the area under the curve of plasma concentration from time zero to the last measurable concentration) covers at least 80% of AUC(0-inf) (the from time zero to infinity), the point when theoretically, 100% of the drug from the organism has been eliminated.

To put that into context, generally, there would be at least three to four samples taken during the terminal elimination phase to accurately obtain the documented result, and in simple terms,  to determine how the body handles the substance.

With decades of experience, the clinical team here at Quinta are true aficionados at both planning, performing, and reporting on such testing. On hand and ready to offer full support not only in sampling time preparation for your projects but also various types of consultation for your pharma needs.