Controlled release from a composite silicone/hydrogel membrane.
To enhance the drug uptake and release capacity of silicone rubber (SR), N-isopropylacrylamide (NIPA) hydrogel particles have been incorporated into a SR membrane. The NIPA particles were thoroughly blended with uncured SR with a certain ratio at room temperature. The mixture was then cast in a Petri dish to 1 mm thickness and cured 10 hours at 90 degrees C. The SR/NIPA composite gel can absorb water approximately equal to its dry weight. Brilliant blue, used as a mock drug, was loaded into the composite gel. Drug release increased exponentially to a final value that is temperature dependent: low at T> =34 degrees C, and high at T< 34 degrees C. This finding is because the hydrophobicity of NIPA changes with temperature. Pulsed release in response to temperature switching between 20 and 39 degrees C has been achieved. Drug uptake and release capability strongly depends upon the structure of the composite gel. The optimal range of NIPA composition is between 75 and 87% by volume. In the cited range, the NIPA particles form an interconnected network that provides a channel for diffusion of drug solution. The SR/NIPA composite gel has promising attributes as a wound dressing and other uses.
University of North Texas, Denton 76203, USA.
Z
Z
Hu
C
C
Wang
K D
KD
Nelson
R C
RC
Eberhart
D000178:Acrylamides / Q000737:chemistry; D000327:Adsorption; D016503:Drug Delivery Systems; D020100:Hydrogels / Q000737:chemistry*; D012826:Silicone Elastomers / Q000737:chemistry*
D000178:Acrylamides; D020100:Hydrogels; D012826:Silicone Elastomers; C067295:N-isopropylacrylamide