Theoretical analysis of release kinetics of coated tablets containing constant and non-constant drug reservoirs

A detailed theoretical analysis of drug release from a two-dimensional membrane-reservoir tablet into a sink is presented. An entire process of drug release was modeled including a phase of drug release from a constant reservoir followed by a phase of non-constant reservoir. Explicit theoretical solutions were obtained for the first time for the two phases and integrated seamlessly to describe a drug release process from a non-steady state to a steady state. The theoretical solutions were useful for the prediction of release kinetics and analysis of formulation variables as demonstrated by various examples including tablets with varying coating thickness, material properties, drug solubility and partition coefficient, anisotropy and temporal idiosyncrasies.