Drug release characteristics of unimolecular polymeric micelles

Biodegradable, unimolecular polymeric micelles possess several features that are attractive for drug delivery applications: Thermodynamic stability, ability to encapsulate and solubilize a hydrophobic guest molecule, biodegradability, as well as size and surface characteristics that prevent rapid clearance by the RES. Here we investigate the potential of these unimolecular polymeric micelles to release a drug for an extended time. Lidocaine was used as a model drug for in vitro studies using a horizontal diffusion cell and cellulose membrane that prevented polymer transport from the source to the receiver compartment. The transport of free lidocaine from source to receiver under sink conditions was zero-order and complete within 8 h. The transport of lidocaine initially encapsulated in polymer was zero-order for the first 14 h, and 96% of the lidocaine was detected within 24 h.