AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 5 716-R720, Copyright © 1984 by American Physiological Society
A model for the distribution and clearance of inert substances in subcutaneous tissue
M. N. Ozisik, R. Hillman and F. Widmer
The subcutaneous space has received attention in recent years as a route
for the continuous administration of drugs and implantation of drug
delivery systems. Yet little work has been devoted to an examination of the
mass transport (distribution) of drugs in the subcutaneous space and the
factors that influence their rate of clearance. A mathematical model is
developed to describe the spreading and resorption of substances infused
into the subcutaneous space. It simulates radial diffusion and flow in the
direction of spreading as well as lateral convection into the systemic
circulation. An analytic solution is obtained for the distribution of the
substance as a function of time and position in the subcutaneous space. Two
independent parameters, v (Peclet no.) and H (generalized Biot no.), are
found to control the transport. Examples are presented to illustrate the
effects of these parameters on the distribution of substances in the
subcutaneous space.
