US5614206A
Expired / Lapsed
US
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Controlled dissolution pellet containing calcium sulfate
Assignee: Wright Medical Technology Inc
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Filing: 1995-03-07
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Granted: 1997-03-25
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Expires: 2015-03-07
Abstract
Abstract This invention relates to the controlled release of calcium sulfate as well as to the controlled release of an additive to a calcium sulfate matrix such as medicaments or pesticides. The controlled release is achieved by a pellet comprising calcium sulfate. The pellet is prepared by the process comprising mixing powder consisting essentially of alpha-calcium sulfate hemihydrate, a solution comprising water, and, optionally, an additive and a powder consisting essentially of beta-calcium sulfate hemihydrate to form a mixture, and forming said mixture into a pellet, wherein said alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate powders have specified properties such as BET surface areas, densities, mean particle sizes, and purifies. The dissolution rate of the calcium sulfate pellet is controlled by varying the weight ratio of the beta-calcium sulfate hemihydrate powder to the alpha-calcium sulfate hemihydrate powder from 0 to about 3. The invention also provides a method of delivering medicament in vivo by implanting a pellet prepared with medicament into a human or an animal.
Inventors
- 👤 Donald A. Randolph
- 👤 Jodi L. Negri
- 👤 Timothy R. Devine
- 👤 Steven Gitelis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:27
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/20; A61K9/2004; A61K9/2009; A61K9/14; A61K9/16; A61K9/1605; A61K9/1611; A61L; A61L27/00; A61L27/02; A61L27/025; A61L27/50; A61L27/54; A61L2300/00; A61L2300/40; A61L2300/402; A61L2300/404; A61L2300/406; A61L2300/412; A61L2300/414; A61L2300/416; A61L2300/60; A61L2300/602
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
237 words
A pellet having a controllable dissolution rate, wherein said pellet comprises calcium sulfate and is prepared by the process comprising: (a) mixing a first powder consisting essentially of alpha-calcium sulfate hemihydrate, and optionally, a second powder consisting essentially of beta-calcium sulfate hemihydrate, with a solution comprising water to form a mixture, and (b) forming said mixture into a pellet, wherein said first powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 0.4 m 2 /g to about 0.9 m 2 /g, a density in the range of from about 2.73 to about 2.80 g/cm 3 , a mean particle size of about 16 μm to about 22 μm, and wherein 90-95 wt. % of the first powder has a particle size distribution from about 1 μm to about 45 μm, wherein said second powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 4.5 m 2 /g to about 7.5 m 2 /g, a density in the range of from about 2.5 g/cm 3 to about 2.6 g/cm 3 , and a mean particle size in the range of from about 10 μm to about 15 μm, and wherein the dissolution rate is controlled by varying the weight ratio of the second powder to the first powder from 0 to about 3.
Claim 2
Dependent Claim
237 words
A pellet having a controllable dissolution rate, wherein said pellet comprises calcium sulfate and is prepared by the process comprising: (a) mixing a first powder consisting essentially of alpha-calcium sulfate hemihydrate, and optionally, a second powder consisting essentially of beta-calcium sulfate hemihydrate, with a solution comprising water to form a mixture, and (b) forming said mixture into a pellet, wherein said first powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 0.4 m 2 /g to about 0.9 m 2 /g, a density in the range of from about 2.73 to about 2.80 g/cm 3 , a mean particle size of about 16 μm to about 22 μm, and wherein 90-95 wt. % of the first powder has a particle size distribution from about 1 μm to about 45 μm, wherein said second powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 4.5 m 2 /g to about 7.5 m 2 /g, a density in the range of from about 2.5 g/cm 3 to about 2.6 g/cm 3 , and a mean particle size in the range of from about 10 μm to about 15 μm, and wherein the dissolution rate is controlled by varying the weight ratio of the second powder to the first powder from 0 to about 3.
Claim 3
Dependent Claim
35 words
The pellet of claim 1 wherein the surface area of the powder consisting essentially of alpha-calcium sulfate hemihydrate is in the range of from about 0.4 m 2 /g to about 0.7 m 2 /g.
Claim 4
Dependent Claim
32 words
The pellet of claim 1 wherein the mean particle size of the powder consisting essentially of alpha-calcium sulfate hemihydrate is in the range of from about 18 μm to about 22 μm.
Claim 5
Dependent Claim
35 words
The pellet of claim 1 wherein the surface area of the powder consisting essentially of beta-calcium sulfate hemihydrate is in the range of from about 5 m 2 /g to about 6 m 2 /g.
Claim 6
Dependent Claim
32 words
The pellet of claim 1 wherein the mean particle size of the powder consisting essentially of beta-calcium sulfate hemihydrate is in the range of from about 13 μm to about 14 μm.
Claim 7
Dependent Claim
35 words
The pellet of claim 1 wherein the ratio of the powder consisting essentially of beta-calcium sulfate hemihydrate to the powder consisting essentially of alpha-calcium sulfate hemihydrate is in the range of from0 to about 0.33.
Claim 8
Dependent Claim
11 words
The pellet of claim 1 wherein said pellet further comprises medicament.
Claim 9
Dependent Claim
20 words
The pellet of claim 7 wherein the medicament is an antibiotic, a chemotherapeutic agent, a growth factor, or an analgesic.
Claim 10
Dependent Claim
17 words
The pellet of claim 8 wherein said antibiotic is tetracycline hydrochloride, vancomycin, tobramycin, gentamicin or a cephalosporin.
Claim 11
Dependent Claim
16 words
The pellet of claim 8 wherein said chemotherapeutic agent is cis-platinum, ifosfamide, methotrexate, or doxorubicin hydrochloride.
Claim 12
Dependent Claim
29 words
The pellet of claim 8 wherein said growth factor is transforming growth factor beta, bone morphogenic protein, basic fiberblast growth factor, platelet-derived growth factor, or other polypeptide growth factors.
Claim 13
Dependent Claim
16 words
The pellet of claim 8 wherein said analgesic is lidocaine hydrochloride, bipivacaine hydrochloride, or ketorolac tromethamine.
Claim 14
Dependent Claim
12 words
The pellet of claim 1 wherein said solution also contains sodium chloride.
Claim 15
Dependent Claim
30 words
The pellet of claim 1 wherein the weight ratio of water to alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate is in the range of from about 0.22 to about 1.
Claim 16
Dependent Claim
29 words
The pellet of claim 14 wherein the weight ratio of water to alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate is in the range of from about 0.27 to 0.30.
Claim 17
Dependent Claim
11 words
The pellet of claim 6 wherein said pellet further comprises medicament.
Claim 18
Dependent Claim
20 words
The pellet of claim 16 wherein the medicament is an antibiotic, a chemotherapeutic agent, a growth factor, or an analgesic.
Claim 19
Dependent Claim
17 words
The pellet of claim 17 wherein said antibiotic is tetracycline hydrochloride, vancomycin, tobramycin, gentamicin or a cephalosporin.
Claim 20
Dependent Claim
16 words
The pellet of claim 17 wherein said chemotherapeutic agent is cis-platinum, ifosfamide, methotrexate, or doxorubicin hydrochloride.
Claim 21
Dependent Claim
16 words
The pellet of claim 17 wherein said analgesic is lidocaine hydrochloride, bipivacaine hydrochloride, or ketorolac tromethamine.
Claim 22
Independent Claim
245 words
A method of delivering medicament in vivo comprising implanting a pellet comprising calcium sulfate and a medicament into a human or an animal, wherein said pellet is prepared by the process comprising: (a) mixing a first powder consisting essentially of alpha-calcium sulfate hemihydrate, medicament, a solution comprising water, and, optionally, a second powder consisting essentially of beta-calcium sulfate hemihydrate, and (b) forming said mixture into a pellet, wherein said first powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 0.4 m 2 /g to about 0.9 m 2 /g, a density in the range of from about 2.73 to about 2.80 g/cm 3 , a mean particle size of about 16 μm to about 22 μm, and wherein 90-95 wt. % of the first powder has a particle size distribution from about 1 μm to about 45 μm, wherein said second powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 4.5 m 2 /g to about 7.5 m 2 /g, a density in the range of from about 2.5 g/cm 3 to about 2.6 g/cm 3 , and a mean particle size in the range of from about 10 μm to about 15 μm, and wherein the dissolution rate is controlled by varying the weight ratio of the first powder to the second powder from 0 to about 3.
Claim 23
Independent Claim
245 words
A method of delivering medicament in vivo comprising implanting a pellet comprising calcium sulfate and a medicament into a human or an animal, wherein said pellet is prepared by the process comprising: (a) mixing a first powder consisting essentially of alpha-calcium sulfate hemihydrate, medicament, a solution comprising water, and, optionally, a second powder consisting essentially of beta-calcium sulfate hemihydrate, and (b) forming said mixture into a pellet, wherein said first powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 0.4 m 2 /g to about 0.9 m 2 /g, a density in the range of from about 2.73 to about 2.80 g/cm 3 , a mean particle size of about 16 μm to about 22 μm, and wherein 90-95 wt. % of the first powder has a particle size distribution from about 1 μm to about 45 μm, wherein said second powder has a purity greater than 98 wt. % calcium sulfate hemihydrate, a BET surface area in the range of from about 4.5 m 2 /g to about 7.5 m 2 /g, a density in the range of from about 2.5 g/cm 3 to about 2.6 g/cm 3 , and a mean particle size in the range of from about 10 μm to about 15 μm, and wherein the dissolution rate is controlled by varying the weight ratio of the first powder to the second powder from 0 to about 3.
Claim 24
Dependent Claim
20 words
The method of claim 21 wherein the medicament is an antibiotic, a chemotherapeutic agent, a growth factor, or an analgesic.
Claim 25
Dependent Claim
17 words
The method of claim 22 wherein said antibiotic is tetracycline hydrochloride, vancomycin, tobramycin, gentamicin or a cephalosporin.
Claim 26
Dependent Claim
16 words
The method of claim 22 wherein said chemotherapeutic agent is cis-platinum, ifosfamide, methotrexate, or doxorubicin hydrochloride.
Claim 27
Dependent Claim
29 words
The method of claim 22 wherein said growth factor is transforming growth factor beta, bone morphogenic protein, basic fiberblast growth factor, platelet-derived growth factor, or other polypeptide growth factors.
Claim 28
Dependent Claim
16 words
The method of claim 22 wherein said analgesic is lidocaine hydrochloride, bipivacaine hydrochloride, or ketorolac tromethamine.
Claim 29
Dependent Claim
12 words
The method of claim 21 wherein said solution also contains sodium chloride.
Claim 30
Dependent Claim
30 words
The method of claim 21 wherein the weight ratio of water to alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate is in the range of from about 0.22 to about 1.
Claim 31
Dependent Claim
29 words
The method of claim 28 wherein the weight ratio of water to alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate is in the range of from about 0.27 to 0.30.
Claim 32
Dependent Claim
23 words
A method of preparing the pellet of claim 1 wherein the mixture is formed into a pellet by subjecting the mixture to pressure.
Claim 33
Dependent Claim
21 words
A method of preparing the pellet of claim 1 wherein the mixture is formed into a pellet by molding the mixture.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2000-03-24 | 2000-09-23 | 2001-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-24 | 2004-09-23 | 2005-03-25 | $3760.00 | Window Closed / Lapsed |
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