Our Research

Discover our recent findings, catch up with news, and review in-depth resources.

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Pharmacokinetics – Area Under the Curve Calculations

The area under the concentration vs. time curve is a useful description of exposure of drug following administration. There are different ways in which AUC may be calculated…

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Pharmacokinetics – Area Under the Curve Calculations

The area under the concentration vs. time curve is a useful description of exposure of drug following administration. There are different ways in which AUC may be calculated, and terminology may vary from one source or text to another. This page summarizes the calculations and terminology that may be encountered.

Bioanalytical data consists of a series of concentrations at various time points following dose administration.

The shape under each pair of data points forms a trapezoid. The area of a trapezoid can be calculated using a variety of rules. For example, the Linear Log Trapezoidal rule will draw a linear line between pairs of data points that are prior to Cmax, and a logarithmic line between data points following Cmax. The linear trapezoidal linear interpolation rule will draw a linear line between each pair of data points:

There are additional rules, and these are specified in our study plans.

The area under each of the trapezoids are summed (shaded area above) to give an AUC:

AUC0-n = Ʃ[0.5*(t2-t1)* (Cp1+Cp2)]

Where a logarithmic trapezoidal rule is employed for a trapezoid, the formula is:

AUCt1-t2 = (t2-t1)*((Cp1-Cp2)/ln(Cp1/Cp2 ))

  • AUC0-last describes the area under the curve up to the last quantifiable time-point (sometimes referred to as AUC0-t)
  • AUC0-x describes the area under the curve limited to a specific time (e.g. AUC0-12h). This time may fall between available data points, in which case interpolation is used to make the calculation
  • AUC0-inf extrapolates the area to infinite time. This requires a terminal elimination phase to be characterized. AUC0-inf comprises AUC0-last plus the extrapolated area AUCt-inf which is calculated by

AUCt-inf  = Cpt / Kel

where Cpt is the plasma concentration at the last quantifiable time point and Kel is the terminal elimination rate constant

  • AUC0-tau describes the area under the curve limited to the end of a dosing interval. The end of the dosing interval may fall between available data points, in which case interpolation is used to make the calculation
  • AUCall describes the area under the curve inclusive of any final time-point that is below the limit of quantitation
 

Zhiyang Zhao, Ph.D.

Chief Scientific Officer

Zhiyang Zhao, Ph.D., serves as Chief Scientific Officer (CSO) at Resolian. Dr. Zhao has over 30 years of pharmaceutical industry experience with special focus on drug metabolism and bioanalysis of small and large molecules in drug discovery and development. Dr. Zhao has previously held positions at Pfizer, GlaxoSmithKline, and Amgen. Before joining Resolian in 2015, Dr. Zhao served as Site Director of Preclinical Research at Amgen in Cambridge, Massachusetts, for over a decade. 

Currently, Dr. Zhao serves as an Adjunct Professor at the Eshelman School of Pharmacy of the University of North Carolina at Chapel Hill, North Carolina, and as Editor-in-Chief of Drug Metabolism & Bioanalysis Letters, a journal by Bentham Science, which publishes in all areas of drug metabolism and bioanalysis. Dr. Zhao received his Ph.D. degree in Medicinal Chemistry from Virginia Polytechnic and State University (popularly known as Virginia Tech) in Blacksburg, Virginia. 

Patrick Bennett

Chief Executive Officer

Patrick Bennett has over 35 years of experience in pharmaceutical analysis and laboratory management. Now CEO at Resolian, Patrick’s experience includes the roles of Strategic Marketing Director for Pharma with Thermo Fisher Scientific, LabCorp, and Vice President of Strategy and Development with PPD. 

Patrick earned a B.S. degree in Toxicology and a M.S. degree in Pharmacology from the College of Pharmacy and Allied Health at St. John’s University and an M.B.A in International Marketing from the Martin J. Whitman School of Management at Syracuse University.