Method of preparing bioerodible polymers having pH sensitivity in the acid range and resulting product
First Claim
1. Bioerodible polymers capable of functioning as carriers of biologically active substances and release thereof by erosion of the polymer when brought into contact with an aqueous environment, said polymers containing in at least a substantial proportion of the polymer molecules an amine functionality such that the rate of erosion of the polymer in an acidic aqueous environment will increase as the pH of the environment diminishes.
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Accused Products
Abstract
Biodegradible polymers are provided which may contain a biologically active substance, e.g. a drug such as insulin, which is released over a period of time as the polymer erodes when in contact with a body fluid. The polymer contains an amine functionality whereby it erodes faster at low acid pH'"'"'s than at higher acid pH'"'"'s. As an example, the polymer may contain insulin and may contain or may have an encapsulating hydrogel containing glucose oxidase. As the blood sugar level of a diabetic person rises, e.g., afte a meal, glucose diffuses into the polymer or hydrogel and is converted to gluconic acid which lowers the pH, and accelerates erosion and the release of insulin.
75 Citations
23 Claims
- 1. Bioerodible polymers capable of functioning as carriers of biologically active substances and release thereof by erosion of the polymer when brought into contact with an aqueous environment, said polymers containing in at least a substantial proportion of the polymer molecules an amine functionality such that the rate of erosion of the polymer in an acidic aqueous environment will increase as the pH of the environment diminishes.
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7. Polymers having the repeating mer unit:
- ##STR10## wherein n is an integer substantially greater than 10;
wherein R1 and R2 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups or may form parts of a cyclic group;
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R is a quadrivalent organic grouping;
R3 and R4 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups or may form parts of a cyclic group;
R5 is an essentially hydrocarbon group which is the residue of a polyol R5 (OH)a wherein a is an integer equal to two or more, such polyol being a single molecular species or a mixture of molecular species; and
wherein such linear chain may be crosslinked with other such chains, at least a substantial portion of the polymers having an amine functionality incorporated in the ○
R or in R5 or in both, whereby the rate of erosion of the polymer in contact with an acidic aqueous medium is substantially greater at lower acidic pH'"'"'s than at higher acidic pH'"'"'s. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
- ##STR10## wherein n is an integer substantially greater than 10;
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15. Compounds having the structure ##STR12## wherein R1 and R2 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups or may form parts of a cyclic group;
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R is a quadrivalent organic grouping;
R3 and R4 are hydrogen or the same or different essentially hydrocarbon groups and may be separate groups or may form parts of a cyclic group; and
R is a linking group. - View Dependent Claims (16)
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- 17. A method of producing biodegradible polymers which undergo faster erosion in an aqueous medium at lower acid pH'"'"'s than at higher acid pH'"'"'s, said method comprising copolymerizing at least two different monomeric species selected to produce a biodegradible polymer, at least one of such species containing an amine functionality.
Specification