GB1588648A

GB1588648A - Disinfecting and sterilizing compositions

Info

Publication number: GB1588648A
Application number: GB4654877A
Authority: GB
Original assignee: GALEN Ltd
Current assignee: GALEN Ltd
Priority date: 1977-11-09
Filing date: 1977-11-09
Publication date: 1981-04-29
Also published as: IE782199L; DE2848724A1; IE47504B1

Description

(54) IMPROVEMENTS IN OR RELATING TO DISINFECTING AND STERILIZING COMPOSITIONS (71) We, GALEN LIMITED, a British company of 34 Church Street; Portadown, Craigavon, County Armagh, Northern Ireland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to compositions of disinfecting and sterilizing agents. More particularly it relates to compositions based on glutaraldehyde which have bactericidal, fungicidal, virucidal and sporicidal properties.

One of the best known and most efficient sterilizing agents is glutaraldehyde. However, glutaraldehyde suffers from certain disadvantages. Glutaraldehyde in acid solution is relatively stable but has very poor sporicidal activity. In alkaline solutions it is effective but not very stable. Attempts have been made to overcome these disadvantages by storing glutaraldehyde under acid conditions and then, just prior to use, adjusting the pH of the aqueous solution of glutaraldehyde to alkaline. Such action however imposes an undesirable burden upon the user.

We have made careful investigations into the action of glutaraldehyde (along and in the presence of other materials) upon cell forms in order to more fully understand the parameters which govern the effectiveness of aqueous glutaraldehyde based solutions for sterilizing purposes. From a study of the effect of glutaraldehyde on the cellular activity of cell forms of Escherichia coli, it is believed that glutaldehyde acts via a combination of a partial sealing of the outer membrane of the cell wall and inactivation of cell wall-associated or periplasmiclocated enzymes. It has been found that the presence of certain materials potentiates the effective action of glutaraldehyde by modifying the cell wall. Study of the action of sodium bicarbonate (which has been the traditional alkalinating agent for converting stored acid glutaraldehyde solutions into more active alkaline glutaraldehyde solutions just prior to use) has shown that the sodium bicarbonate does not act only as a means of changing the pH. The sodium ions arising from the sodium bicarbonate modify the cell wall. The sodium ions cause disruption of the loose layer and outer membrane of the cell enabling increased uptake and penetration of glutaraldehyde to its optimum site of action. It would appear that the sodium ions assist in releasing enzymes from the cell wall constituents thus rendering them more susceptible to inactivation by glutaraldehyde. Similar results were achieved by replacing the sodium bicarbonate with sodium chloride, supporting the belief that the sodium ion action on the cell wall was as significant a parameter as the requirement for an alkaline pH.

Further investigations were then made into the effects of metal ions having higher valencies than sodium. It was found that such metal ions of higher valencies were more effective than monovalent ions such as sodium.

It has been suggested (in British Patent Specification No. 1.443,786) that dormant spores can be killed by the use of a composition having a pH of less than 7 and consisting of a solvent which is water or a mixture of water and a lower monohydric alcohol, glutaraldehyde and dissolved quantities of certain highly ionizable salts at temperatures above 15"C. Said Specification does not clearly show the applicability of such a method to bacteria.

Furthermore it is primarily directed to the use of monovalent salts and does not suggest that salts of higher valent metals would be more efficacious. Indeed it seems to be directed to the advantages of using salts of monovalent metal ions. Said specification also does not disclose any criteria for the effective concentrations of salts of metal ions of different valencies. In contrast we have found that when salts of monovalent divalent, and trivalent cations are added to aqueous glutaraldehyde solutions in equimolar amounts, particularly in the range of 0.15 Molar to 0.5 Molar, the salts of trivalent cations, for example aluminium chloride, produce much more effective sterilizing and disinfecting compositions than salts.of monovalent cations, for example, sodium chloride.

According to one embodiment of the present invention there is provided a composition for sterilizing and disinfecting which comprises water or a mixture of water and a monohydric alcohol having I to 3 carbon atoms, together with glutaraldehyde and a trivalent metal ions.

The composition is preferably at a pH not above 7.

For the sake of convenience, the present invention will be particularly described with reference to the use of A13+ as the metal ion. However other trivalent metal ions may be used.

The preferred trivalent ions are those of Group IIIb of the Periodic Table of Elements e.g.

aluminium. The metal ions can be introduced in salt form such as sulphate or halide (particularly chloride), for example aluminium chloride. Referring again to the investigations described above, the presence of Al3+ in aqueous glutaraldehyde solutions was found to increase glutaraldehyde inactivation of cellular alkaline phosphatase by causing a drift of the enzyme towards the outer membrane. A still further increase in activity was demonstrated when a surfactant, preferably of the anionic type, was added to the aluminiumglutaraldehyde formulation and this effect was related to increased uptake of the disinfectant.

As mentioned above, acidic solutions of glutaraldehyde have very slow activity. However it has been found that an aqueous acidic solution of glutaraldehyde containing Alp6(EB has comparable activity to an aqueous solution of glutaraldehyde made alkaline by the presence of, for example, sodium bicarbonate.

Study of the effect of varying concentrations of Al3+ on the effectiveness of the glutaraldehyde solution has shown increasing effectiveness up to about 0.2 Molar but no significant increase for concentrations over 0.2 Molar. However concentrations as high as 0.5 Molar may be used. It is preferred to use a concentration for Al3+ of at least 0.15 Molar.

Extrapolation of investigations on bacteria to spores has shown similar results.

The incorporation of a surfactant into the glutaraldehyde-A13+ solution potentiates the effect of the glutaraldehyde. Indeed it has been found that in some cases a synergistic effect is achieved when compared with aqueous glutaraldehyde containing Al3 or surfactant alone.

The preferred surfactants are anionic. Suitable anionic surfactants include detergents which are ionizable at the pH of acid solutions of glutaraldehyde. The pKa values would generally be less than 4. preferably less than 3.5. The anionic surfactants maybe, for example, alkyl sulphates or alkylaryl sulphonates. The alkyl sulphates usually have 8 to 18 carbon atoms in the alkyl group, for example lauryl or dodecyl sulphate. The anionic surfactnat is usually employed in an amount of less than 1 0%buy weight, preferably less than 5 % by weight when using an alkyl sulphate.

Non-ionic surfactants such as the ethoxylated fatty alcohols. ethoxylated alkylphenols or ethoxylated lanolin may be used. Preferably the fatty alcohol or alkyl phenol has been ethoxylated to a degree or greater than 9 moles of ethylene oxide, and the lanolin has been ethoxylated to a degree within the range of 40 to 70 mols of ethylene oxide. However. use of a non-ionic surfactant with Al3+ or has been found not to be as effective as use of an anionic surfactant (as sodium salt) with Awl3+. The non-ionic surfactant is usually employed in an amount of less than 3%by weight. preferably 0.5 to I .5%by weight.

Use of fairly high concentration of Al3 (or indeed other trivalent metal ions) salt and fairly high concentrations of surfactants can however lead. in some instances. to a salting out effect resulting in precipitation from the solution. This problem can however be overcome by employing the Al + and surfactants as a single compound. We have also found that divalent metal ion-containing surfactants may be used in the composition of the present invention.

Accordingly the present invention also provides a composition for disinfecting and stcrilizing. which comprises water or a mixture of water and monohydric alcohol having 1 to 3 carbon atoms. together with glutaraldehyde and a divalent or trivalent metal ion-containing surfactant.

In the case of divalent ions it is preferred to use alkaline earth metal ions while in the case of trivalent ions, the preferred ions are those of Group IlI(b) of the Periodic Table of Elements.

e.g. aluminium.

When using such single compounds. the trivalent or divalent metal ions are'cations of surfactants. preferably anionic surfactants. Examples of such compounds are aluminium dodecyl or lauryl sulphate. aluminium dodecyl or lauryl benzene sulphonate magnesium dodecyl or lauryl sulphate and magnesium dodecyl or lauryl benzene sulphonate.

If a divalent or trivalent metal ion-containing surfactant is used in the composition. the concentration of the divalent or trivalent metal ion may be as low as 0.001 Molar. Further concentrations of divalent or trivalent metal ions of up to 0.5 Molar may be used.

The concentration of glutaraldehyde in the aqueous composition affects the time required for sterilization. The concentration of glutaraldehyde is usually from 0.005 to 1 or/% by weight of the composition. However, different uses of the glutaraldehyde composition affect the preferred concentration. For example, a composition for bactericidal use preferably has at least a 0.005% by weight concentration of glutaraldehyde, a composition for fungicidal use preferably has at least a 0.05% by weight concentration of glutaraldehyde, while a composition for sporicidal use preferably contains at least 1 %by weight glutaraldehyde.

As stated above, alkaline solutions of glutaraldehyde have greater activity than acid solutions. A similar difference occurs in solutions containing Awl + or Mg2+ (alone or with surfactant). However, such alkaline solutions have reduced stability compared with acid solutions. If it is desired to use an alkaline pH any conventional alkalinating agent, for example, sodium bicarbonate, may be used.

The compositions of the present invention are temperature dependent in use. Increasing temperature (particularly with acid solutions) leads to increasing activity and indeed a synergistic effect may be observed. The compositions are usually employed at a temperature of at least ambient temperature, preferably in the range of 15 to 75 0C.

It is possible to use the compositions of the present invention in conjunction with ultrasonic irradiation. A mixture of water and alcohol is used in the composition of the present invention, the alcohol may be, for example, isopropanol.

The compositions of the present invention may contain inhibitors.

The compositions of the present invention may be used in disinfecting and sterilizing in the presence of metallic, particularly ferrous, articles. However, at acid pH, many of the conventional additives for rust inhibition have been demonstrated to be ineffective for the formulations of the present invention. It has been further demonstrated that the sulphate or sulphonate derivatives of hydroxy carboxylic acids, such as those derived from ricinoleic and hydroxystearic acids, are effective corrosion inhibitors for the formulations of this invention.

The aforementioned sulphate and sulphonated derivatives of hydroxy carboxylic acids are also anionic surfactants. It is further possible by the use of the said carboxylic acids, to present the preferred ion, anionic surfactant and corrosion or rust inhibitor in the form of a single compound. The amount of corrosion or rust inhibitor employed is usually 0.1 to 5% by weight, preferably substantially 1 % by weight, of the composition.

A particularly useful inhibitor is sulphated castor oil (such as marketed by Ellis Jones & Co.) when using higher concentrations of the sulphated oil it is preferred also to use a small amount of organic acid e.g. citric acid to ensure an acid pH.

The present invention will now be further described with reference to, but is in no manner limited to, the following Examples. Results in the Tables marked with an asterisk are outside the scope of the present invention and are included for comparative purposes only. In the Examples: Empilan KA880 is an 80% solution of ethoxylated fatty alcohols in water sold by the Marchon Division of Albright and Wilson Ltd "Empilan" is a trade mark; Solan E is a solid water soluble ethoxylated lanolin sold by Crods Chemical Ltd; ("Solan" is a Trade Mark); and Empicol ML26a is a 26.5%w/v solution of magnesium dodecyl sulphate in water, which also contains 1.5% w/v magnesium sulphate and 0.2% w/v magnesium chloride, sold by the Marchon Division of Albright and Wilson Ltd ("Empicol" is a Trade Mark).

Examples 1 to 3 Several aqueous glutaraldehyde compositions (containing 2.0% w/ v glutaraldehyde) were prepared and their effectiveness was measured in deactivating the following organisms: Bacteria, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus Fungi, Trichophyton mentagrophytes var interdigitale , Aspergillus niger Spores. Bacillus subtilis, Bacillus pumilis, Clostridium sporogenes B. subtilis exhibited the greatest resistance to the sterlising effects of all the formulations studied and thus for clarity the data presented pertains to this organism. Activity of the formulations was examined using a percentage kill method as described by S.P. Gorman and E.M. Scott (Microbios Letters. 1976). Fungicidal activity of the solutions was determined as described by S.P. Gorman and E.M. Scott (J. app. Bact. 1977). All solutions were freshly prepared in deionised water, accurate pH values recorded and added to the organism at the specified temperature. At specified intervals samples were removed into 1 % (w/v) glycine solution (S.P. Gorman and E.M. Scott. Microbios Letters. 1976) to inactivate excess glutaraldehyde before plating onto agar for incubation and subsequent enumeration of surviving organisms. Controls were carried out in every case using standard solutions of both acid and alkaline glutaraldehyde. The details and results of Examples 1 to 3 are set forth in Tables I to 3 respectively.

Table 1 (Example 1) Time in minutes for 99.9 %kill at 0C Additive Concn. pH 18 37 55" None* - 3.6 > 5h 25 20 AIC13 0.2M 3.6 100 17 13 NaCI* 0.2M 3.6 250 22 17 B. subtilis initial spore count: 108/ml; glutaraldehyde 2%w/v Table 2 (Example 2) Time in minutes for 99.9% kill at 0C Additive Concn. pH 18 37 55" None* - 3.6 > 5h 25 19 NaHCO3* - 7.9 40 17 13 Magnesium dodecyl sulphate 0.7% 3.8 90 14 4 EmpicolML26a 2.5% 3.8 95 15 4 EmpicolML26a 10.0% 4.5 55 7 2 Sodiumdodecyl 2.5sic 4.0 150 22 10 sulphate B. subtilis initial spore count: 108/my; glutaraldehyde 2%w/v Table 3 (Example 3) Time required (min or h-hours) for 99.9% kill at 18"C. with formulation stored for (weeks) Additive Concn. pH 0 2 4 24 52 None - 3.6 > 5h > 5h > 5h > 5h > 5h NaHCO3 * 0.3% 7.9 40 2-3h > 5h > 5h > 5h Empicol ML26a 10.0% 4.5 55 55 55 55 60 B. subtilis initial spore count: 108/ml; glutaraldehyde 2%w/v Example I illustrates the effect of monovalent and trivalent ions on the sporicidal efficacy of aqueous glutaraldehyde formulations. The results (Table I) indicate that the trivalent metal ions potentiate the sporicidal activity of acid glutaraldehyde to a greater extent than the monovalent ions. It shows the higher efficiency of AICI3. which we believe is due not to the triple charge but to its astringency and protein precipitation. Table I also shows the effect of temperature on the sporicidal efficacy of the above glutaraldehyde formulations. increasing temperature producing a highly significant increase in activity.

Example ' illustrates the effect of formulation of the glutaraldehyde with the magnesium salt of an anionic surfactant. In this instance all the solutions are clear and have sporicidal efficacies at room temperature which approach that of freshly bicarbonate alkalinated glutaraldehyde. At elevated temperatures the efficacy of the formulations is significantly in excess of that of freshly bicarbonate alkalinated glutaraldehyde.

Example 3 illustrates the effect of storage on the sporicidal efficacy of the novel aqueous acidic glutaraldehyde formulations of this invention. The sporicidal efficacy of the formulations has been demonstrated to be largely unaffected by storage at room temperature for a period of up to one year. By contrast. the alkalinated formulations studied retained an acceptable level of sporicidal efficacy for a 14 day period only.

Example 4 In a similar manner to Examples I to 3. several glutaraldehyde compositions (containing 0.01 % w/v glutaraldchydc) were prepared and their effectiveness at I 80C. was measured in deactivating Escherichia coli, the initial count of which was 108/ ml. The results are shown in Table 4.

Table 4 (Example. 4) Additive Concn. pH Time (minutes) for 99.9%kill None * 4.6 120 NaHCO3* 0.3% 7.9 20 NaCI* 0.2M 4.5 60 AICI3 0.2M 4.5 25 Example 5 In a similar manner to Examples 1 to 3, several glutaraldehyde compositions (containing 0.5% w/v glutaraldehyde) were prepared and their effectiveness at 180C. was measured in deactivating A. niger and T. mentagrophyte, the initial spore count of each of which was 106/my. The results are shown in Table 5.

Table 5 (Example 5) Additive Concn. pH Time in hours for 99.999% kill of spore of A. niger T. mentagrophyte None* - 4.6 > 3 > 3 NaHCO3* 0.3% 7.9 2 1 Nail* 0.2M 4.5 3 1.5-2 AlCI3 0.2M 4.3 2.5 1.5 EmpicolML26A 2.5% 4.8 2.4 1.3 EmpicolML26A 10% 4.9 2.2 Example 6 In a similar manner to Examples 1 to 3, several glutaraldehyde solutions (containing 0.01 % w/v glutaraldehyde) were prepared and their effectiveness at 18"C. was measured in deactivating Escherichia coli, the viable count of which was 108/my. The results are shown in Table 6.

Table 6 (Example 6) Additive Concn. (%) pH Time (minutes) for a 99.9%kill Empicol ML26A 0.1 5.9 105 Empicol ML26A 1.0 6.5 90 Empicol ML26A 2.5 7.0 22 Empicol ML26A 5.0 7.3 17 Empicol ML26A 10.0 7.6 15 None* -- 4.6 120 NaHCO3* 0.3% 7.9 20 WHAT WE CLAIM IS: 1. A composition for sterilizing and disinfecting. which comprises water or a mixture of water and a monohydric alcohol having l to 3 carbon atoms. together with glutaraldehyde and a trivalent metal ion.

2. A composition as claimed in claim 1 in which the trivalent metal ion is a Group III(b) metal ion.

3. A composition as claimed in claim 2, in which the trivalent metal ion is present in the form of a chloride or sulphate salt.

4. A composition as claimed in claim 3, in which the trivalent metal ion is present in the form of aluminium chloride.

5. A composition as claimed in any of claims l to 4. in which the trivalent metal ion is present in a concentration of at least 0. I 5 molar.

6. A composition as claimed in any of claims I to 5. in which the trivalent metal ion is present in a concentration of not more than 0.5 molar.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. deactivating Escherichia coli, the initial count of which was 108/ ml. The results are shown in Table 4. Table 4 (Example. 4) Additive Concn. pH Time (minutes) for 99.9%kill None * 4.6 120 NaHCO3* 0.3% 7.9 20 NaCI* 0.2M 4.5 60 AICI3 0.2M 4.5 25 Example 5 In a similar manner to Examples 1 to 3, several glutaraldehyde compositions (containing 0.5% w/v glutaraldehyde) were prepared and their effectiveness at 180C. was measured in deactivating A. niger and T. mentagrophyte, the initial spore count of each of which was 106/my. The results are shown in Table 5. Table 5 (Example 5) Additive Concn. pH Time in hours for 99.999% kill of spore of A. niger T. mentagrophyte None* - 4.6 > 3 > 3 NaHCO3* 0.3% 7.9 2 1 Nail* 0.2M 4.5 3 1.5-2 AlCI3 0.2M 4.3 2.5 1.5 EmpicolML26A 2.5% 4.8 2.4 1.3 EmpicolML26A 10% 4.9 2.2 Example 6 In a similar manner to Examples 1 to 3, several glutaraldehyde solutions (containing 0.01 % w/v glutaraldehyde) were prepared and their effectiveness at 18"C. was measured in deactivating Escherichia coli, the viable count of which was 108/my. The results are shown in Table 6. Table 6 (Example 6) Additive Concn. (%) pH Time (minutes) for a 99.9%kill Empicol ML26A 0.1 5.9 105 Empicol ML26A 1.0 6.5 90 Empicol ML26A 2.5 7.0 22 Empicol ML26A 5.0 7.3 17 Empicol ML26A 10.0 7.6 15 None* -- 4.6 120 NaHCO3* 0.3% 7.9 20 WHAT WE CLAIM IS:

1. A composition for sterilizing and disinfecting. which comprises water or a mixture of water and a monohydric alcohol having l to 3 carbon atoms. together with glutaraldehyde and a trivalent metal ion.

7. A composition as claimed in any of claims 1 to 6, which also contains a surfactant.

8. A composition as claimed in claim 7, in which the surfactant is an anionic surfactant.

9. A composition as claimed in claim 8, in which the anionic surfactant has a pKa of less than 4.

10. A composition as claimed in claim 8 or claim 9, in which the anionic surfactant is an alkyl sulphate or alkylaryl sulphonate.

11. A composition as claimed in claim 10, in which the alkyl sulphate is dodecyl or lauryl sulphate.

12. A composition as claimed in claim 7, in which the surfactant is a non-ionic surfactant.

13. A composition as claimed in claim 12, in which the non-ionic surfactant is an ethoxylated fatty alcohol or alkyl phenol which has been ethoxylated to a degree of greater than 9 moles of ethylene oxide or an ethoxylated lanolin which has been ethoxylated to a degree within the range 40 to 70 mols of ethylene oxide.

14. A composition as claimed in any of claims 1 to 13, in which the trivalent metal ion is added to the composition in the form of a simple inorganic salt.

15. A composition as claimed in claim 14, in which the salt is aluminium chloride.

16. A composition as.claimed in any of claims 1 to 15, which also contains a corrosion inhibiting agent.

17. A composition as claimed in claim 16, in which the corrosion inhibiting agent is a sulphated or sulphonated hydroxy carboxylic acid.

18. A composition as claimed in claim 17, in which the corrosion inhibiting agent is a sulphate or sulphonate derivative of ricinoleic or hydroxy stearic acid.

19. A composition as claimed in any of claims 16 to 18. in which the corrosion inhibiting agent is present in a concentration of 0. I to 5 %by weight.

20. A composition as claimed in any of claims 1 to 19, in which the glutaraldehyde is present in a concentration of 0.005 to 1 0 % by weight of the composition.

21. A composition as claimed in any of claims 1 to 20 which has a pH not above 7.

22. A composition as claimed in claim 1 and substantially as hereinbefore described with reference to any of Examples 1 , 4 or 5.

23. A composition for disinfecting and sterilizing, which comprises water or a mixture of water and monohydric alcohol having 1, to 3 carbon atoms, together with glutaraldehyde and a divalent or trivalent metal ion-containing surfactant.

24. A composition as claimed in claim 23, in which the divalent metal ion is a cation of an alkaline earth metal.

25. A composition as claimed in claim 23, in which the trivalent metal ion is a cation of a Group III(b) metal.

26. A composition as claimed in any of claims 23 to 25. in which the metal ion is present in a concentration of at least 0.001 molar.

27. A composition as claimed in any of claims 23 to 26, in which the metal ion is present in a concentration of not more than 0.5 molar.

28. A composition as claimed in claim 23, in which the surfactant is an anionic surfactant.

29. A composition as claimed in claim 28. in which the surfactant is aluminium dodecyl or lauryl sulphate or aluminium dodecyl or lauryl benzene sulphonate.

30. A composition as claimed in claim 28. in which the surfactant is in the form of magnesium dodecyl or lauryl sulphate or magnesium dodecyl or lauryl benzene sulphonate.

3 1. A composition as claimed in any of claims 23 to 30 which also contains a corrosion inhibiting agent.

32. A composition as claimed in claim 31. in which the corrosion inhibiting agent is sulphated or sulphonated hydroxy carboxylic acid.

33. A composition as claimed in claim 32. in which the corrosion inhibiting agent is a sulphate or sulphonate derivative of ricinoleic or hydroxy stearic acid.

34. A composition as claimed in any of claims 23 to 28. in which the divalent or trivalent metal ion-containing surfactant is sclected so that it has. in addition. corrosion inhibiting properties.

35. A composition as claimed in claim 34. in which the surfactant is derived from a sulphated or sulphonated hydroxy carboxylic acid.

36. A composition as claimed in claim 35. in which the surfactant is derived from a sulphate or sulphonate derivative of ricinoleic or hydroxy stearic acid.

37. A composition as claimed in any of claims 31 to 33. in which the corrosion inhibiting agent is present in a concentration of 0. I to 5%by weight.

38. A composition as claimed in any of claims 23 to 37. in which the glutaraldehyde is present in a concentration of 0.005 to 10%. by weight ofthe composition.

39. A composition as claimed in any of claims 23 to 38 which has a pH not above 7.

40. A composition as claimed in claim 23 and substantially as hereinbefore described with reference to any of Examples 2.3,5 or 6.

41. A method of sterilizing and disinfecting which comprises contacting with a composition as claimed in any of claims 1 to 21.

42. A method as claimed in claim 41,in which the contact is performed at 15 to 75 0C.

43. A method of sterilizing and disinfecting as claimed in claim 41 and substantially as hereinbefore described with reference to any of Examples 1,4 or 5.

44. A method of sterilizing and disinfecting which comprises contacting with a composition as claimed in any of claims 23 to 39.

45. A method as claimed in claim 44, in which the contact is performed, at 150 to 75 C.

46. A method of sterilizing and disinfecting as claimed in claim 44 and substantially as hereinbefore described with reference to any of Examples 2, 3,5 or 6.

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