Stabilised compositions having antibacterial activity
A stabilised composition having antibacterial, antiviral and/or antifungal activity, said composition comprising silver ions and a ligand, characterised in that the composition comprises a complex of silver and a ligand selected from the group consisting of 5,5-disubstituted hydantoins in which the substituents do not comprise conjugated unsaturated bonds and barbituric acid and derivatives thereof stabilising silver ions against reduction to free silver in a hydrophilic environment, and that the composition has a solubility in water higher than 10 mg Ag/l is stable during sterilisation and retains the activity without giving rise to darkening or discoloration of the dressing during storage.
1. A stabilized composition having antibacterial, antiviral and/or antifungal activity, said composition containing silver ions in complex with a ligand, wherein said composition comprising a complex of silver ions; and
a ligand selected from the group consisting of:
5,5-dimethyl-barbituric acid or 1,5,5-trimethyl-barbituric acid,
wherein said silver ions are stabilized against reduction to free silver in a hydrophilic environment and the composition has a solubility in water greater than 10 mg Ag/l.
2. A composition as claimed in claim 1 , wherein said composition contains a second silver compound with a solubility less than 10 mg Ag/l.
3. A composition as claimed in claim 1 , wherein said composition is mixed into a polymer composition.
4. A composition according to claim 3 , wherein the polymer is a hydrophilic polymer.
5. A composition as claimed in claim 4 , wherein the hydrophilic polymer forms a gel, a foam or a xerogel.
6. A composition as claimed in claim 4 , wherein said composition is mixed into an alginate.
7. A composition as claimed in claim 1 , wherein the concentration of silver is from 0.1 to 20% by weight of the dry matter.
8. A method of producing the composition of claim 1 , said method comprising the steps of:
1) dissolving a silver salt in water;
2) adding a ligand selected from the group consisting of 5,5-dimethyl-barbituric acid or 1,5,5-trimethyl-barbituric acid to the solution of the silver salt at a controlled pH;
3) leaving the resulting solution for a period of between about 2 to 100 hours;
4) optionally adjusting the pH to a value of 7-11;
5) isolating the resulting mixture; and
6) optionally drying and micronizing the mixture.
9. A medical device which comprises the the composition of claim 1 .
10. A method of treating infection in a human being by applying the medical device of claim 9 .
11. The medical device of claim 9 , wherein said device is a catheter having a hydrophilic coating.
12. The method of treating infection in a human being of claim 10 , wherein said medical device is a catheter having a hydrophilic coating.
13. The medical device according to claim 9 , wherein the medical devices is selected from the group consisting of a wound dressing, an ostomy appliance, and an incontinence device.