Mathematical models describing the drug release kinetics from pressure sensitive adhesive matrix

Abstract Several mathematical models for facilitating the interpretation of the release data cf lipophilic drugs from highly lipophilic matrices were proposed. Aminopyrine (AMP), ethinylestradiol (EE) and dipropylphthalate (DPP) were used as model drugs, and acrylic type pressure sensitive adhesive (PSA) was used as a model lipophilic matrix. Release experiments were performed using a diffusion cell at 37°C. AMP was completely released from the PSA, whereas only a fraction of EE and DPP loaded was released. There are usually several resistances involved in the diffusion of a drug through the matrix, such as interfacial transfer resistance ( R ) and transport resistance across the stagnant layer ( H ) during the drug release process; several equations containing above resistances were therefore developed in the Laplace dimension and used to interpret the obtained release data for the three drugs. Analysis of the results suggested that the stagrant layer could be neglected when using our type of diffusion cell and that the release data of the drugs from the PSA matrix could be interpreted by introducing the interfacial migration resistance and partition coefficient between the matrix and receiver solution into a Fick's diffusion equation.