Patent US3856805A successfully refreshed from Google Patents.
US3856805A
Expired / Lapsed
US
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Silver zinc allantoin complex
Assignee: University of Washington
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Filing: 1971-06-16
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Granted: 1974-12-24
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Expires: 1991-06-16
Abstract
Abstract A silver zinc allantoinate composition and method for making it. The silver zinc allantoinate is prepared by a novel process producing high yields above 90 percent and the resultant silver zinc allantoinate has a low water solubility of about 0.02 percent at 25* C. providing for slow release of silver and zinc ions in medication. The silver zinc allantoinate can be incorporated into various carriers such as ointment, creams, lotions, aerosol sprays, and the like, for topical application for control of bacteria and fungi.
Inventors
- 👤 H Margraf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:56
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/10; A61K9/12; A61K9/06; A61K9/08; A61K9/14; C; C07; C07D; C07D233/00; C07D233/54; C07D233/66; C07D233/88; C07F; C07F3/00; C07F3/003
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
5 words
SILVER-ZINC-ALLANTOINATE OF THE FORMULA (C4H5O3N4AG)2:ZN(OH)2.
Claim 2
Dependent Claim
5 words
SILVER-ZINC-ALLANTOINATE OF THE FORMULA (C4H5O3N4AG)2:ZN(OH)2.
Claim 3
Independent Claim
54 words
A method of preparing silver-zinc-allantoinate which comprises using in the proportion of 100 parts zinc sulfate heptahydrate and 100 parts allantoin in boiling water, adding 100 parts silver nitrate in aqueous solution, adding to the aforementioned ammonia to form a precipitate and filtering the precipitate from the solution to obtain the precipitate as silver-zinc-allantoinate.
Claim 4
Independent Claim
54 words
A method of preparing silver-zinc-allantoinate which comprises using in the proportion of 100 parts zinc sulfate heptahydrate and 100 parts allantoin in boiling water, adding 100 parts silver nitrate in aqueous solution, adding to the aforementioned ammonia to form a precipitate and filtering the precipitate from the solution to obtain the precipitate as silver-zinc-allantoinate.
Claim 5
Dependent Claim
25 words
The method of claim 2 in which silver is recovered from the filtered solution by adding hydrochloric acid to said solution to precipitate silver chloride.
Claim 6
Dependent Claim
18 words
The method of claim 2 in which the precipitate is washed with cold water containing 1.0% hydrogen peroxide.
Claim 7
Independent Claim
100 words
A method of preparing silver-zinc-allantoinate which comprises using in the proportion of 100 parts zinc sulfate heptahydrate and 100 parts allantoin in 2 liters of distilled water, stirring and heating said mixture to 100*C and adding 200 milliliters of a 50% aqueous solution of silver nitrate, slowly adding a 29 percent aqueous ammonia solution in the amount of about 90 to 95 milliliters until a pH of 7.5 is attained to obtain a precipitate, filtering said mixture through a suction filter to separate the precipitate from the solution, washing the precipitate with cold water and drying to provide the silver-zinc-allantoinate.
Claim 8
Independent Claim
100 words
A method of preparing silver-zinc-allantoinate which comprises using in the proportion of 100 parts zinc sulfate heptahydrate and 100 parts allantoin in 2 liters of distilled water, stirring and heating said mixture to 100*C and adding 200 milliliters of a 50% aqueous solution of silver nitrate, slowly adding a 29 percent aqueous ammonia solution in the amount of about 90 to 95 milliliters until a pH of 7.5 is attained to obtain a precipitate, filtering said mixture through a suction filter to separate the precipitate from the solution, washing the precipitate with cold water and drying to provide the silver-zinc-allantoinate.
Claim 9
Dependent Claim
25 words
The method of claim 5 in which silver is recovered from the filtered solution by adding hydrochloric acid to said solution to precipitate silver chloride.
Claim 10
Dependent Claim
19 words
The method of claim 5 in which the precipitate is washed with cold water containing 1.0 percent hydrogen peroxide.
References Cited (Backward Citations)
US2104738A
Cited
US2336131A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |