Patent ID: 8420121

Claim:
A drug delivery vehicle, comprising a first hydrogel comprising an opioid antagonist, wherein release of the opioid antagonist from the first hydrogel is stimulated by an increase in the concentration of CO 2 in environment of the drug delivery vehicle; and a second hydrogel comprising an opioid, wherein release of the opioid from the second hydrogel is substantially CO 2 -independent, or is decreased by an increase in the concentration of CO 2 in the environment of the drug delivery vehicle, wherein the second hydrogel comprises 25 to 50 mol % of the aminoalkyl (meth)acrylate of Formula 9 or an acid salt thereof, wherein G is oxygen or NR′ where R′ is hydrogen or C 1-3 alkyl group, R is hydrogen or methyl, R 1 is a straight chain or branched C 1-4 alkylene group, and each R 2 is independently hydrogen, C 1-4 alkyl, or a labile group; 40 to 70 mol % of an acetal (meth)acrylate of Formula 5 wherein R is hydrogen or methyl, and each R 4 and R 5 is independently a straight chain or branched C 1-4 alkyl group, or R 4 and R 5 together form a cycloaliphatic ring having a total of 5 to 7 carbon atoms; and 1 to 5 mol % of a crosslinker of Formula 6 wherein each R is independently hydrogen or methyl, n is 1 to 4, and R 6 and R 7 is independently hydrogen or a straight or branched chain C 1-3 alkyl group, or R 6 and R 7 together form a cycloaliphatic ring having a total of 5 to 6 carbon atoms or a cycloheteroaliphatic ring having 4 to 6 carbon atoms and an oxygen or sulfur ring atom.