US4608278A
Expired / Lapsed
US
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Small particule formation and encapsulation
Assignee: Ohio State University Research Foundation
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Filing: 1984-06-15
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Granted: 1986-08-26
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Expires: 2004-06-15
Abstract
Abstract The present invention is concerned with the simultaneous formation and encapsulation of small particles from aqueous solutions of compounds whose solubility is greater at a first pH than at a second pH. The process is preferably used to prepare a readily soluble encapsulated pharmaceutically active compound.
Inventors
- 👤 Sylvan G. Frank
- 👤 Arne F. Brodin
- 👤 Chih-Ming J. Chen
- 👤 Siriporn Panthuvanich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:50
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/48; A61K9/50; A61K9/5005; A61K9/5021; A61K9/5036; A61K9/5042; A61K9/5026; A61K9/5047; A61K9/5052; A61K9/5057; A61K9/5089; B; B01; B01J; B01J13/00; B01J13/02; B01J13/06; B01J13/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
135 words
A process for encapsulating a weakly acidic organic compound whose solubility in water is greater at a first pH than at a second pH which process comprises: (a) dissolving said compound in water in the presence of sufficient base to raise the pH to said first pH and at least 2 pH units above the pKa of the compound, together with an encapsulating material and an electrolyte which is effective, but present in an amount just insufficient to cause coacervation of the encapsulating material without interacting with it; (b) stirring and titrating the solution with a titrant effective to reduce the pH of said solution to said second pH to cause the concurrent precipitation of the compound as small particles and formation of a coacervate of the encapsulating material; and (c) gelling the encapsulating material.
Claim 2
Dependent Claim
135 words
A process for encapsulating a weakly acidic organic compound whose solubility in water is greater at a first pH than at a second pH which process comprises: (a) dissolving said compound in water in the presence of sufficient base to raise the pH to said first pH and at least 2 pH units above the pKa of the compound, together with an encapsulating material and an electrolyte which is effective, but present in an amount just insufficient to cause coacervation of the encapsulating material without interacting with it; (b) stirring and titrating the solution with a titrant effective to reduce the pH of said solution to said second pH to cause the concurrent precipitation of the compound as small particles and formation of a coacervate of the encapsulating material; and (c) gelling the encapsulating material.
Claim 3
Dependent Claim
33 words
A process according to claim 1, wherein the pharmaceutically active compound is selected from the group consisting of bacampicillin, griseofulvin, indomethacin, sodium sulfadiazine, erythromycin, theophylline, salicylic acid, acetylsalicylic acid, chlorozoxazone, lidocaine and alaproclate.
Claim 4
Dependent Claim
26 words
A process according to claim 1, wherein the encapsulating material is selected from the group consisting of gelatin, methylcellulose, sodium carboxymethylcellulose, cellulose acetate phthalate, and polyvinylpyrrolidone.
Claim 5
Dependent Claim
134 words
A process for encapsulating a weakly basic organic compound whose solubility in water is greater at a first pH than at a second pH which process comprises: (a) dissolving said compound in water in the presence of sufficient acid to lower the pH to said first pH and at least 2 pH units below the pKa of the compound, together with an encapsulating material and an amount of an electrolyte which is effective, but just insufficient to cause coacervation of the encapsulating material without interacting with it; (b) stirring and titrating the solution with a titrant effective to raise the pH of said solution to said second pH to cause the concurrent precipitation of the compound as small particles and formation of a coacervate of the encapsulating material; and (c) gelling the encapsulating material.
Claim 6
Dependent Claim
134 words
A process for encapsulating a weakly basic organic compound whose solubility in water is greater at a first pH than at a second pH which process comprises: (a) dissolving said compound in water in the presence of sufficient acid to lower the pH to said first pH and at least 2 pH units below the pKa of the compound, together with an encapsulating material and an amount of an electrolyte which is effective, but just insufficient to cause coacervation of the encapsulating material without interacting with it; (b) stirring and titrating the solution with a titrant effective to raise the pH of said solution to said second pH to cause the concurrent precipitation of the compound as small particles and formation of a coacervate of the encapsulating material; and (c) gelling the encapsulating material.
Claim 7
Dependent Claim
26 words
A process according to claim 4 wherein the compound is sulfadiazine in sodium sulfate solution containing ethyl alcohol and the encapsulating material is a gelatin solution.
Claim 8
Dependent Claim
22 words
A process according to claim 5, wherein the ratio of compound to encapsulating material to wetting agent to electrolyte is about (0.1-6):(0.1-4):(0.1-10):(0.4-48).
Claim 9
Dependent Claim
14 words
A process according to claims 1 or 4 wherein the compound is pharmaceutically active.
Claim 10
Dependent Claim
14 words
The process according to claim 7 wherein the first pH is an acid pH.
Claim 11
Dependent Claim
17 words
A process according to claim 1 or 4 wherein a wetting agent is used in step a.
Claim 12
Dependent Claim
18 words
A process according to claim 1 or 4 wherein, if needed, the temperature is controlled in step b.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-25 | 1990-02-24 | 1990-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-25 | 1994-02-24 | 1994-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-25 | 1998-02-24 | 1998-08-26 | $7700.00 | Window Closed / Lapsed |