Biodegradable dexamethasone polymer capsule for long-term release

We have developed sustained Dex (dexamethasone) capsule implants for sustained local delivery for inflammatory disease treatment. Four different biodegradable polymers were used as capsule materials: polycaprolactone (PCL), poly(lactic acid) (PLA), 90:10 poly(lactic-co-glycolide) (PLGA), and 50:50 PLGA. The drug release profiles from the four types of capsule were compared and the profiles were fit to a cylindrical reservoir first-order kinetics model. As a result, 50:50 PLGA showed the fastest release with the largest permeability and partition coefficient at 0.4909 nm/s and 1.9519, respectively. On the other hand, PCL showed the slowest release with the smallest permeability and partition coefficient at 0.1915 nm/s and 0.8872, respectively. The results indicate that the drug release kinetics are highly correlated with hydrophobicity of the polymer sheet: the more hydrophobic, the slower the drug release kinetics for the hydrophilic drug. The in vitro therapeutic efficacy of the Dex implant was also explored using TNF- α stimulated human umbilical vein endothelial cells (HUVECs), showing effective suppression of IL-6 levels with the implant compared to free Dex with minimal toxicity. Overall, this study suggests that the release trend of Dex from implants follows the hydrophobicity of each polymer, and the Dex implant inhibits the IL-6 expression effectively.