Control of drug release from polymer matrices impregnated with magnetic beads —a proposed mechanism and model for enhanced release

The need to regulate drug release rates in applications such as suppression of diabetic symptoms and birth control has previously led to the development of delivery systems containing small magnetic beads uniformly imbedded within drug-laden polymer matrices. An oscillating magnetic field imposed on such systems triggers a significant increase in release rate. A mechanism for enhanced release is proposed here, which draws upon the similarity between the observed increase in mass transfer by pulsation, e.g., promotion of axial diffusion in a cylinder with pulsed (but zero net) flow and enhanced drug release by the oscillating field. A mathematical model is derived based on this analogy. Its predictions are consistent with general observations and provide correlations of release rates with the frequency and amplitude of the oscillating magnetic field and the intrinsic drug diffusivity.