Introduction To Pharmacokinetics
Method Of Residuals
INTRODUCTION
When the concentration-time curve for a drug given by a non-intravenous route is plotted on a semilogarithmic graph, often the first part of the curve is curved and the latter part is linear. The first part of the graph reflects the absorption process.
The method of residuals is a useful technique that allows a second graph to be plotted using the data from the first, curved area of the graph.
The resulting residuals graph indicates whether the absorption process follows first order kinetics.
Where first order kinetics are involved, the residuals graph can be used to find a reasonable approximation of the absorption half-life and from that, the absorption rate constant.