Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Theoretical considerations along with extensive Monte Carlo simulations are used to calculate the lag time before initiation of diffusion-controlled drug release in multilayer planar devices an outer layer containing no drug. The presented results also relevant formulations coated by a drug-free membrane as well other reservoir systems. diffusion molecules through towards medium is considered, giving rise observed time. We have determined dependence on thickness and coefficient layer, initial concentration surface area device. A simple expression, obtained analytical solution equation, provides approximate estimate for that describes numerical reasonably well; according this relation, proportional squared over corresponding inversely logarithm linear number density initially loaded inner layer.