Lag time in the dual sorption model for percutaneous absorption with finite skin-receptor boundary clearance

The lag time in the dual sorption model for percutaneous drug absorption with finite skin-receptor boundary clearance is examined. The effect of the change in the perfusional resistance on the lag time in the dual sorption model is found to be similar to, but a little less prominent than, that in the linear model. It is suggested that the lag time is roughly proportional to the amount in the skin at the steady state. Two numerical methods are used in predictor-corrector combination to obtain a numerical solution of the parabolic partial differential equation, together with the associated initial and boundary conditions, which arise in a nonlinear mathematical model of percutaneous drug absorption. Numerical estimates are obtained for the drug concentration profiles, the cumulative amount of drug excreted into the blood, the flux in the transient and steady states, the lag time, and the amount of drug in the skin per unit area in the steady state.