Process for disinfecting instruments

Details Process for disinfecting instruments Process for disinfecting instruments

1999-06-10

2003-04-01

Warden, Sr., Robert J. (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Process disinfecting, preserving, deodorizing, or sterilizing

Using disinfecting or sterilizing substance

C422S029000, C510S101000

Reexamination Certificate

active

06540960

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for disinfecting instruments, more especially medical instruments, using aqueous peroxidic formulations.
2. Discussion of Related Art
Over the years, the chemical disinfection of instruments using aqueous formulations has been the subject of numerous studies in which various antimicrobial agents have been proposed for disinfection. Preparations based on aldehydes have been the most widely used in practice, although preparations containing quaternary ammonium compounds, phenols, alcohols and other disinfecting agents have also been used. By contrast, preparations based on peroxidic agents, more especially peracetic acid, have acquired very little significance for this particular application. One of the main reasons for this lies in the poor stability of such aqueous preparations in storage. In view of the broad antimicrobial activity of peroxides, there has been no shortage of attempts to overcome the disadvantage of their poor stability in storage. For example, it is proposed in DE-OSS 26 55 599 and 28 15 400 to prepare the aqueous preparations required for disinfection just before use from more stable precursors, namely from sodium perborate and anhydrides. According to DE-OS 27 01 133, the aqueous preparations are obtained from compounds which release hydrogen peroxide and aromatic acyloxycarboxy acids. However, only a few of these compounds give disinfecting solutions with sufficiently broad activity, in addition to which these acylating agents can only be stored for a limited period in admixture with the necessary inorganic peroxides on account of decomposition reactions. “Sekusept Pulver (Sekusept Powder)” is a commercially available product which dissolves in water to form a disinfecting preparation by reaction of sodium perborate with tetraacetyl ethylenediamine (TAED). This product, which is based on an N-acyl compound, has a broad action spectrum and is stable in storage. Although a high standard in the disinfection of medical instruments has already been achieved in this way, more work is being done to improve the peroxidic systems in order to eliminate the gaps which still exist in the action spectrum and disadvantages in use. For example, it is proposed in DE-OS 36 15 787 to use the magnesium salt of monoperoxyphthalic acid instead of inorganic hydrogen peroxide donors in the production of such preparations. However, the use of this organic peroxide involves considerably greater outlay on equipment compared with the use of the storage stable and inexpensive inorganic peroxides. Accordingly, the problem addressed by the present invention was to achieve an improvement in disinfection systems based on inorganic peroxides and N-acyl compounds. One of the associated problems to be solved in this regard was to develop a disinfection process which would even enable mycobacteria to be safely disinfected. In addition, easy handling, high stability in storage and only a very slight tendency towards corrosion would be guaranteed.
It has now been found that a significant improvement in the known disinfection systems based on inorganic hydrogen peroxide donors and N-acyl compounds can be achieved by a remarkably simple measure.
DESCRIPTION OF THE INVENTION
The present invention relates to a process for disinfecting medical instruments by treating the instruments with a microbicidally active aqueous preparation in which the following two steps A and B are successively carried out in the production of the microbicidal preparation:
A: reacting hydrogen peroxide or peroxidic compounds which form hydrogen peroxide in water in an aqueous alkaline medium with N-acyl compounds which are capable under these conditions of acylating hydrogen peroxide,
B: reducing the pH value of the preparation obtained in step A and optionally diluting the preparation so that a pH value in the range from 7 to 9 and preferably in the range from 7.5 to 8.5 is established in the preparation used for disinfection.
Through the comparatively simple measure of subsequently reducing the pH value, which can be done with any of the usual acids, a considerable increase in antimicrobial activity coupled with only a very slight tendency towards corrosion is achieved without losing any of the advantages of the known process.
In the production of the microbicidally active aqueous preparation, step A of the process according to the invention starts out from hydrogen peroxide or from peroxidic compounds which immediately release hydrogen peroxide when dissolved in water. These peroxidic compounds can be adducts of hydrogen peroxide with various carriers, which are sometimes also referred to as perhydrates, for example urea perhydrate, sodium citrate perhydrate or sodium carbonate perhydrate (Na
2
CO
3
×1.5 H
2
O
2
), which normally is also referred to as sodium percarbonate. True inorganic peroxo compounds which hydrolyze spontaneously in water, for example the sodium perborates, for example sodium perborate monohydrate and sodium perborate tetrahydrate, are also suitable. By contrast, organic peroxo compounds in which the peroxo group is directly attached to carbon are unsuitable. Sodium percarbonate and the mono- and tetrahydrates of sodium perborate are particularly preferred for the purposes of the process according to the invention, the monohydrate being most particularly preferred. Several per compounds may also be used at one and the same time.
In principle, suitable N-acyl compounds for the reaction in step A are any compounds of this group which have also been described in detergent chemistry as so-called bleach activators for reaction with hydrogen peroxide in alkaline wash liquors. Suitable N-acyl compounds are, in particular, those which contain another keto group at the nitrogen which carries the acyl group and/or in which the nitrogen is part of a heterocyclic ring system. Examples of suitable N-acyl compounds are the polyacylated alkylenediamines, such as for example tetraacetyl ethylenediamine, acylated glycol urils, above all tetraacetyl glycol uril, N-acylated hydantoins, hydrazides, triazoles, triazines, urazoles, diketopiperazines, sulfuryl amides, lactams and cyanurates. Tetraacetyl ethylenediamine (TAED), tetraacetyl glycol uril (TAGU) and 1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT) are preferred for the purposes of the process according to the invention, tetraacetyl ethylenediamine being particularly preferred. Several N-acyl compounds may of course also be used at one and the same time.
The reaction of the compound yielding hydrogen peroxide and the N-acyl compound in step A is carried out by introducing the two compounds into water successively or, preferably, at the same time. If the peroxidic compound, for example sodium percarbonate and sodium perborate, has sufficient alkalinity, there may be no need to add alkalizing agents. Otherwise, compounds showing an alkaline reaction, preferably inorganic salts, for example sodium carbonate, alkali metal phosphates or alkali metal borates, will have to be added to establish a pH value which, even after the reaction has been completed, is still in the alkaline range, preferably above 8.5 and more preferably between 9 and 11. The ratio of the hydrogen peroxide donor to the N-acyl compound is preferably selected so that 0.5 to 10 moles and preferably 1 to 5 moles of hydrogen peroxide are available per mole of reactive acyl groups in the N-acyl compound. Accordingly, about 0.1 to about 1% by weight and, more particularly, about 0.2 to about 0.6% by weight of peroxidic compounds and 0.1 to about 1% by weight and, more particularly, about 0.2 to about 0.5% by weight of N-acyl compound, based on the total weight of the preparation in step A, are preferably used.
The reaction between hydrogen peroxide and the N-acyl compound in step A is a time reaction which is dependent on the concentration of the reactants, the reactivity of the N-acyl compound, the pH value of the solution and the temperature. The reaction can be accelerated by increasing the concen

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