CONTROLLED-RELEASE FROM A COATED PARTICLE - EFFECTS OF INITIAL CONDITIONS AND METHODS OF SOLUTION

The exact effects of three initial conditions - time lag, burst release, and steady state concentration profile - on drug release from a coated spherical matrix containing dissolved drug into a finite amount of well stirred elution liquid have been analyzed. The degree of the effect of initial conditions on drug release depends on the diffusivity ratio of coating layer to core matrix and the radius ratio of the coated particle to the core. For the case where drug concentration in the core is dependent on time only, the differences between the exact and the pseudo-steady state solutions are computed, therefore, pros and cons for the pseudo-steady state solution, which is simple and direct, can he anchored on exact comparison.