The development of a peak-time criterion for designing controlled-release devices.
This work consists of estimating dynamic characteristics for topically-applied drugs when the magnitude of the flux increases to a maximum value, called peak flux, before declining to zero. This situation is typical of controlled-released systems with a finite donor or vehicle volume. Laplace transforms were applied to the governing equations and resulted in an expression for the flux in terms of the physical characteristics of the system. After approximating this function by a second-order model, three parameters of this reduced structure captured the essential features of the original process. Closed-form relationships were then developed for the peak flux and time-to-peak based on the empirical representation. Three case studies that involve mechanisms, such as diffusion, partitioning, dissolution and elimination, were selected to illustrate the procedure. The technique performed successfully as shown by the ability of the second-order flux to match the prediction of the original transport equations. A main advantage of the proposed method is that it does not require a solution of the original partial differential equations. Less accurate results were noted for longer lag times.
Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 0702, USA.
Laurent
L
Simon
Logic and Computation Group, Physics Engineering Program, School of Sciences and Humanities, EAFIT University, Medellin, Colombia.
Juan
J
Ospina
D000279:Administration, Cutaneous; D003692:Delayed-Action Preparations / Q000737:chemistry / Q000493:pharmacokinetics*; D004058:Diffusion; D015195:Drug Design; D008954:Models, Biological; D012869:Skin Absorption; D012995:Solubility
D003692:Delayed-Action Preparations
Controlled release; Diffusion; Mathematical models; Peak time