Title:  Use of biologically active glass as a drug delivery system

United States Patent:  6,197,342

Assignee:  Thut; Paul D. (Baltimore, MD); Litkowski; Leonard J. (Towson, MD)

Filed:  September 21, 1998

This invention relates to a synthetic bone replacement material impregnated with drugs such as antibiotics and growth hormones, which facilitate and promote the regeneration of bone and/or soft tissue. Methods for making the impregnated material and its medical use are also taught.

SUMMARY OF THE INVENTION

An aspect of the present invention is a particulate, biologically active, ceramic-glass material in conjunction with one or more microencapsulated therapeutically beneficial drugs, capable of releasing the drugs at a predetermined rate when placed in a physiological environment, either in bone or soft tissue. This impregnated biologically active, ceramic-glass material is referred to as "ceramodrug matrix".

A second aspect of the present invention is a method for preparing the ceramodrug matrix of the first aspect comprising the following sequential steps:

a) Forming one or more drugs into biodegradable micro capsules which degrade in physiological fluids at a pH level higher than about 7,

b) Forming a colloidal suspension of the biologically active, ceramic-glass material by mixing the finely divided biologically active, ceramic-glass material in one or more solvents, optionally void of suspending agent,

c) Stirring the micro capsules prepared in step a with the colloidal suspension prepared in step b to yield a cosuspension of micro capsules of drug and the biologically active, ceramic-glass, and

d) Removing the solvent in a sequential manner from the suspension formed in step c yielding a ceramodrug matrix.

A third aspect of the present invention is a method for promoting the regeneration of missing or damaged bone tissue in a mammal comprising replacing the missing or damaged bone tissue with ceramic-glass bone replacement material, impregnated with at least one therapeutically beneficial drug in microencapsulated form, capable of releasing the drug at a predetermined rate when placed in a physiological environment.

A fourth aspect of the present invention is a method for the controlled release of therapeutically beneficial drugs into the bone or soft tissue of a mammal in need of such drugs by placing ceramic-glass material, impregnated with at least one therapeutically beneficial drug in microencapsulated form, capable of releasing the drug at a predetermined rate when placed in a physiological environment into the bone or soft tissue of the mammal.

Claim 1 of 5 Claims

What is claimed is:

1. A method for impregnating a biologically active, ceramic-glass material with at least one beneficial, physiologically active agent to form a ceramodrug matrix comprising the steps:

a) forming one or more drugs into a biodegradable microencapsulated form which degrades in physiological fluids at pH level higher than about 7,

b) forming a colloidal suspension of the biologically active, ceramic-glass material by mixing the finely divided biologically active, ceramic-glass material in one or more solvents, optionally void of suspending agent,

c) stirring the drug in microencapsulated form prepared in step a with the colloidal suspension prepared in step b to yield a cosuspension of microencapsulated drug and the biologically active, ceramic-glass, and

d) removing the solvent in a sequential manner from the suspension formed in step c yielding a ceramodrug matrix impregnated, uniformly or in gradients, with one or more drugs in microencapsulated form.

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