BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Sustained release Primary objective of controlled release devices: SUSTAINED RELEASE General rate expression 0 k Want to match release rate to in vivo uptake/degradation rate to obtain a constant effective concentration of drug ON BOARD -Toxic dose t Design of Eroding Polymer Controlled Release Devices Continuous release Mechanisn∥ hydrolysis Surface-eroding matrix bulk-eroding matrix Protein or Lecture 5- Controlled Release Devices 6 of 14BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Sustained release • Primary objective of controlled release devices: SUSTAINED RELEASE • General rate expression: dc = kc n n = 0 -> dc = k dt dt • Want to match release rate to in vivo uptake/degradation rate to obtain a constant effective concentration of drug ON BOARD: c(t) ceff(t) Minimal effective dose Toxic dose t t Design of Eroding Polymer Controlled Release Devices Continuous Release: Mechanism III hydrolysis Surface-eroding matrix bulk-eroding matrix Protein or Small-molecule drug Lecture 5 – Controlled Release Devices 6 of 14