Preparation of homogeneous hydrogel copolymers
First Claim
1. A method for centrifugally casting a biocompatible copolymer having predetermined equilibrium water content (EWC) value formed by the addition polymerization of a mixture containing an ethylenically unsaturated hydrophilic monomer A and an ethylenically unsaturated hydrophilic monomer B copolymerizable therewith, said copolymer being useful as a hydrogen membrane in the diffusion therethrough of a selected active compound in an aqueous medium at a predetermined rate which comprises:
- a. determining the EWC values of hydrogel homopolymer of monomer A (homopolymer A) and hydrogel homopolymer of monomer B (homopolymer B);
b. determining the relationship of the EWC values of the homogeneous hydrogel copolymers of mixtures of monomer A and monomer B (copolymers AB) versus the chemical composition of said copolymers AB;
c. selecting the targeted EWC value and determining the chemical composition of homogeneous copolymer AB having this targeted EWC value;
d. forming a polymerizable liquid mixture containing said monomer A and said monomer B in amounts sufficient to yield said homogeneous copolymer AB having the targeted EWC value;
e. filling a tube comprising a core of smooth uniform cylindrical surface and closure means to prevent loss of the mixture during rotation, with a predetermined quantity of the liquid mixture;
f. rotating the tube while maintaining a longitudinal axis of the tube parallel to the ground and effecting the rotation at a speed sufficient to cause radially outward displacement of the liquid monomers to assume a cylindrically-shaped liquid cartridge shape having a predetermined configuration within said tube;
g. subjecting the tube to polymerization conditions to convert said liquid state cartridge to a predetermined solid state hollow plastic cartridge; and
h. recovering a biocompatible, non-degradable, water-swellable, water-insoluble, homogeneous copolymer AB consisting essentially of monomer A units and monomer B units in the form of a cylindrical cartridge having walls of uniform thickness between its smooth external and internal cylindrical surfaces.
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Abstract
A method is provided for the preparation of homogeneous copolymers having aredetermined equilibrium water content (EWC) value formed by the addition polymerization of a mixture of ethylenically unsaturated monomer A and ethylenically unsaturated monomer B, for example, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate. The method requires determining the EWC values of the hydrogel homopolymer of hydrophilic monomer A (homopolymer A) and the hydrogel homopolymer of hydrophilic monomer B (homopolymer B); determining the relationship of the EWC values of the homogeneous copolymers AB versus the chemical composition of said copolymers AB; selecting the targeted EWC value and determining the chemical composition of copolymer AB having the targeted EWC value; forming a polymerizable mixture of monomer A and monomer B in amounts sufficient to yield copolymer AB having the targeted EWC value; and effect the polymerization reaction to yield copolymer AB characterized by the targeted EWC value. A method is also provided for the preparation of a delivery device including a drug contained in the reservoir of the hydrogel of copolymer AB, said device being characterized by its capability of eluting or releasing the drug through the hydrogel membrane to a delivery environment at a predetermined rate. There is also disclosed a sterilized kit containing a trocar or hypodermic needle/syringe and the aforesaid drug delivery device having a cylindrical shape with a rounded or bullet-like extremity.
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Citations
40 Claims
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1. A method for centrifugally casting a biocompatible copolymer having predetermined equilibrium water content (EWC) value formed by the addition polymerization of a mixture containing an ethylenically unsaturated hydrophilic monomer A and an ethylenically unsaturated hydrophilic monomer B copolymerizable therewith, said copolymer being useful as a hydrogen membrane in the diffusion therethrough of a selected active compound in an aqueous medium at a predetermined rate which comprises:
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a. determining the EWC values of hydrogel homopolymer of monomer A (homopolymer A) and hydrogel homopolymer of monomer B (homopolymer B); b. determining the relationship of the EWC values of the homogeneous hydrogel copolymers of mixtures of monomer A and monomer B (copolymers AB) versus the chemical composition of said copolymers AB; c. selecting the targeted EWC value and determining the chemical composition of homogeneous copolymer AB having this targeted EWC value; d. forming a polymerizable liquid mixture containing said monomer A and said monomer B in amounts sufficient to yield said homogeneous copolymer AB having the targeted EWC value; e. filling a tube comprising a core of smooth uniform cylindrical surface and closure means to prevent loss of the mixture during rotation, with a predetermined quantity of the liquid mixture; f. rotating the tube while maintaining a longitudinal axis of the tube parallel to the ground and effecting the rotation at a speed sufficient to cause radially outward displacement of the liquid monomers to assume a cylindrically-shaped liquid cartridge shape having a predetermined configuration within said tube; g. subjecting the tube to polymerization conditions to convert said liquid state cartridge to a predetermined solid state hollow plastic cartridge; and h. recovering a biocompatible, non-degradable, water-swellable, water-insoluble, homogeneous copolymer AB consisting essentially of monomer A units and monomer B units in the form of a cylindrical cartridge having walls of uniform thickness between its smooth external and internal cylindrical surfaces. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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- 19. As an article, a biocompatible, non-biodegradable, water-swellable, water-insoluble, hydrophilic cartridge of copolymer AB defining a reservoir or core and useful as a rate-limiting barrier in a drug delivery device capable of being implanted in an animal by perforation, said cartridge characterized by a oval cylindrical shape at its closed end, and an open end distal to the closed end, smooth unscored internal and external cylindrical surfaces, a uniform thickness between said surfaces, said copolymer AB consisting essentially of from about 25 to 70 weight % of 2-hydroxyethyl methacrylate (monomer A) units and from about 75 to 30 weight % of monomer B units, and possessing a predetermined EWC value in the range of from about 25 to about 75 weight %.
Specification