Mesoscopic simulation of the drug release mechanism on the polymeric vehicle P(ST-DVB) in an acid environment

In this work, the drug release mechanism of a polymeric delivery vehicle (polymeric microsphere) is investigated using dissipative particle dynamics (DPD) simulations. Polymer nanoparticles are interesting drug-delivery systems because drugs can be encapsulated inside the shell, which exhibits swelling properties that depend on pH conditions. Albendazole is selected as the model drug, whereas poly(styrene-divinylbenzene) P(ST-DVB) copolymer is the carrier. The DPD simulation shows that drug release of the P(ST-DVB) carrier in an acidic environment occurs via a diffusion mechanism (swelling followed by diffusion). Four transient stages were detected during the drug release: (i) swelling of the polymeric microsphere, (ii) the generation of pores, (iii) drug diffusion in the polymeric matrix and (iv) drug release towards the acid medium. All transient states of the drug release process of the polymeric carrier in an acid environment are described and analysed in this paper. The outcomes obtained from the DPD simulations are consistent with the available experimental results, and they provide a mesoscopic methodology for the evaluation and prediction of new advanced polymeric carriers of pharmaceutical interest.