Measurement of Bioavailability: Pharmacokinetic Methods

Pharmacokinetic methods, like plasma drug concentration and urinary excretion studies, assume a drug's pharmacokinetic profile influences its efficacy.

Plasma drug concentration-time studies involve drug assays using collected blood samples. The resulting plasma drug concentration versus time plot highlights the time of peak plasma concentration, the peak plasma drug concentration, and area under the plasma drug concentration-time curve.

A smaller t_max indicates a faster absorption rate, while a higher C_max suggests an increased peak drug concentration due to greater absorption, a faster absorption rate, or slower elimination. The AUC reflects the drug’s total bioavailability.

Urinary drug excretion studies employ parameters like cumulative drug amount in the urine , rate of drug excretion dD_u/dt, and total excretion time t^∞.

reflects total drug absorption through the cumulative urine drug concentration-time plot. In the dD_u/dt-time graph, the excretion rate initially peaks and diminishes as the elimination completes. t^∞ marks the drug absorption and excretion span and critically compares the different drug products.