Composition comprising antimicrobial metal ions and a quaternary cationic surfactant

1. An antimicrobial wound dressing comprising a silver ion from a silver salt, a quaternary cationic surfactant, and ethylenediaminetetra-acetic acid (EDTA) present as the di-, tri- or tetra-basic salt of EDTA at a level of less than 2% by weight, wherein the silver ion is included in the antimicrobial wound dressing at a level of from 0.01% to 10%.

2. A The antimicrobial wound dressing as claimed in claim 1 having a pH of 4 to 8.

3. The antimicrobial wound dressing as claimed in claim 1 wherein the quaternary cationic surfactant is a quaternary ammonium surfactant.

4. The antimicrobial wound dressing as claimed in claim 1 wherein the quaternary cationic surfactant is selected from the group of the salts where the cation is benzethonium, benzalkonium, dimethyldiakylonium, alkylpyridinium and alkyltrimethylammonium.

5. A process for making an antimicrobial wound dressing comprising:

(i) obtaining an absorbent wound dressing, and

(ii) treating the absorbent wound dressing such that the absorbent wound dressing contains a silver ion from a silver salt, a quaternary cationic surfactant, and ethylenediaminetetra-acetic acid (EDTA) present as the di-, tri- or tetra-basic salt of EDTA at a level of less than 2% by weight,

wherein the silver ion is included in a composition at a level of from 0.0001% to 0.02% by weight if the composition is in aqueous solution, or if the silver ion is included in the composition at a level of from 0.01% to 10% by weight.

6. The antimicrobial wound dressing as claimed in claim 1 having a pH of between 4 and 7.

7. The antimicrobial wound dressing as claimed in claim 1 having a pH of between 4.5 and 5.5.

8. The antimicrobial wound dressing as claimed in claim 1 wherein the EDTA is present at a level from 0.2% to 1% by weight.

9. The antimicrobial wound dressing as claimed in claim 1 wherein the quaternary cationic surfactant is present at a level of more than or equal to 0.025% by weight.

10. The antimicrobial wound dressing as claimed in claim 1 wherein the quaternary cationic surfactant is present at a level of between 0.05% and 4% by weight.

11. The antimicrobial wound dressing of claim 1 further comprising a buffering agent.

12. The antimicrobial wound dressing of claim 11 wherein the buffering agent is present in an amount of about 0.5% to 2% by weight.

13. The antimicrobial wound dressing of claim 11 wherein the buffering agent is selected from the group comprising citric acid/di-sodium hydrogen phosphate, citric acid/sodium citrate and acetic acid/sodium acetate.

14. The antimicrobial wound dressing of claim 7 wherein the pH is around 5.5.

15. The process of claim 5 , wherein the quaternary cationic surfactant is selected from the group of the salts where the cation is benzethonium, benzalkonium, dimethyldiakylonium, alkylpyridinium and alkyltrimethylammonium.

16. The process of claim 5 , wherein the quaternary cationic surfactant is present at a level of more than or equal to 0.025% by weight.

17. The process of claim 5 , wherein the quaternary cationic surfactant is present at a level of between 0.05% and 4% by weight.