Mathematical modeling of delivery of chemotherapeutic drugs to human tissues: an analytical approach

Introduction Man’s war against dangerous afflictions has led to the development of potent formulations and requires complicated dosage patterns. They require controlled and targeted delivery to maximize therapeutic efficacy and minimize side-effects. Chemotherapy has been recognized as a successful means of arresting cancer, which is the third biggest killer among humans. Cancerous tumors are characterized by their rapid spread across the diseased tissue and successively deteriorating conditions. However, it necessitates repeated dosage at specific times, and conventional delivery methods result in unnecessary delay in reaching the targeted location and expose other organs to the effect of the drugs. The drug delivery is thus desired to be precisely targeted and controlled. This has resulted in previous attempts at designing novel, bio-implantable, polymercoated delivery devices that can release the drug at a specified rate. We design and model a novel device that allows electrically regulated release of an ionic drug through an electroactive polymer membrane into a tumor-affected tissue. Doped electro active polymers like polypyrrole show considerable ability to conduct ions and even behave as a switch by alternating its oxidized and reduced states on reversal of electric potential. Our drug delivery device consists of a cylindrical capsule comprising of a drug reservoir containing the ionic drug solution and a set of batteries for creating the desired electric field. The entire capsule is surrounded by a layer of selectively doped electroactive polymer. The device has been implanted at the center of the tumor such that the tumor has progressed symmetrically from all sides. The anionic drug diffuses out under the action of the electric field, permeates through the electroactive membrane as it reacts with the charged polymer groups and is released into the tissue, where it reacts with the biological cells.