A Disinfectant

FIELD OF INVENTION

This invention relates to a long acting human skin disinfectant, for example for the hands.

BACKGROUND

It is known to apply a disinfectant liquid to the human skin to kill germs, for example bacteria and virus’. A problem with many known disinfectants is that they are only effective for a short period and have to be reapplied frequently otherwise the person using them is relatively unprotected from infection if, for example, they touch a surface on which germs are located.

OBJECT OF THE INVENTION

It is an object of preferred embodiments of the invention to go at least some way towards addressing the above problem. While this applies to preferred embodiments, it should not be seen as a limitation on claims expressed more broadly. The object of the invention in its broadest form is simply to provide the public with a useful choice.

DEFINITIONS

The term “comprises” or “has”, if and when used in this document in relation to a combination of features, should not be seen as excluding the option of additional features in the combination that are not mentioned.

SUMMARY OF THE INVENTION

According to one aspect the invention comprises the use of Organosilane and Benzalkonium in the manufacture of a disinfectant comprising: a) 0.25% - 0.35 % wt 3-(trimethoxysilyl)propyl dimethyl octadecyl ammonium salt; and b) 0.09% - 0.11% wt Benzalkonium; wherein the disinfectant is for providing, and provides, effective sanitising protection* on human skin for about 24 hours or more. * The term “effective sanitising protection” means that the disinfectant kills >99% (preferably >99.99%) of germs on human skin.

Optionally the disinfectant comprises: a) 0.25% - 0.35 % wt 3-(trimethoxysilyl)propyl dimethyl octadecyl ammonium chloride; and b) 0.09% - 0.11% wt Benzalkonium.

Optionally the disinfectant comprises: a) about 0.3 % wt 3-(trimethoxysilyl)propyl dimethyl octadecyl ammonium chloride; and b) about 0.1% wt Benzalkonium.

Optionally the Benzalkonium is in salt form.

Optionally the salt form comprises Benzalkonium Chloride.

Optionally the sanitising protection is against Coronavirus.

Optionally the sanitising protection is against SARS-CoV-1 and/or SARS-CoV-2 (eg CoVid- 19 causing Coronavirus).

Optionally the disinfectant comprises Phenoxyethanol which functions in the disinfectant as a preservative.

Optionally the Phenoxyethanol is present in the disinfectant at 0.7% - 1 .3% wt.

Optionally the Phenoxyethanol is present in the disinfectant at 0.8% - 1 .2% wt.

Optionally the Phenoxyethanol is present in the disinfectant at 0.9% - 1.1% wt.

Optionally the Phenoxyethanol is present in the disinfectant at about 1% wt.

Optionally the disinfectant comprises Ethylhexylglycerin which functions in the disinfectant as a preservative.

Optionally the Ethylhexylglycerin is present in the disinfectant at 0.07% - 0.13% wt.

Optionally the Ethylhexylglycerin is present in the disinfectant at 0.08% - 0.12% wt. Optionally the Ethylhexylglycerin is present in the disinfectant at 0.09% - 0.11% wt.

Optionally the Ethylhexylglycerin is present in the disinfectant at about 0.1% wt.

Optionally the sanitising protection is against one or more of E.hirae, P. aeruginosa, S. aureus, E coli, Norovirus, Candida, MRSA, Salmonella, Listeria, Flu Virus and MHV1 virus.

Optionally the sanitising protection is against one or more of Enterococcus hirae, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.

Optionally the disinfectant is for providing, and provides, effective sanitising protection on human hands for about 24 or more hours.

Preferably the disinfectant is for application as a liquid to the skin liberally to provide the effective sanitising protection. For example an amount of 0.5 ml - 1 ml, and preferably about 0.75ml, was found to be sufficient for two hands of an adult male of average size.

DETAILED DESCRIPTION

Three aqueous foaming disinfectant formulations were prepared to have the make-up shown in the tables below.

Formulation A Formulation B

Formulation C

In each case the Formulation was prepared as follows-

Step 1

Dissolve all the 3-(trimethoxysilyl)propyl dimethyl octadecyl ammonium chloride in a sufficient portion of water so it makes up a pre-mix totaling about 6% weight of final product. Step 2

Dissolve or suspend all the benzalkonium chloride in a sufficient portion of the water to provide a pre-mix solution or suspension totaling 0.2% weight of final product.

Step 3

In a separate mixing vessel, add water totaling 90.8% weight of the final product.

Step 4

Separately add each of the premixes (described in steps 1 and 2) to the water of step 3, and blend.

Step 5

Add all the phenoxyethanol and ethylhexylglycerin to the contents of the mixing vessel, and blend.

Step 6

Add all the glycerin to the components in the mixing vessel, and blend.

Step 7

Mix well (for >10 minutes) until all the ingredients are homogenized.

Tests for Disinfectant Performance

Each formulation was tested to see how effective it was in killing germs. This included a quantitative suspension test to evaluate bactericidal activity according to the well-known European test standard EN 13727. The formulations were also tested for virucidal activity by the surface carrier technique of ASTM 1053. Additionally, each formulation was subjected to tests to determine its effectiveness at 24 hours after being applied to human skin (hands). The tests were carried out as follows.

Step 1 (Culture Growth)

Two test organisms were selected and evaluated in the trial:

• Staphylococcus aureus NZRM 147 (ATCC 6538)

• Escherichia coli NZRM 2577 (ATCC 8739) Culture suspensions were prepared for the organisms using overnight culture plates. The culture growth was harvested from each plate and inoculated to 10mL Tryptone Soy Broth (TSB) to achieve an approximate organism count of 10 ⁹ cfu/mL.

Step 2 (Chemical Inactivation)

A combination of neutraliser and dilution was used to achieve an effective neutralising system. In particular, Tryptone soy broth with 0.5% Lecithin and 4% Tween 20 (TLT) was used as a neutralising solution. Hand Sanitizer Formulation at ‘ready to use’ (RTU) concentration was diluted at a ratio of 1 :1000 (10pL in 10mL TLT, the same volume and dilution ratio as treated Vitro-skin 2cm ² ). 10mL of the diluted formulation was then individually spiked to give a cell level sufficient to render a test organism concentration within the countable range. In the presence of TLT the antimicrobial property of the test products was neutralized in order to recover any viable micro-organisms. The recovery of the test organism in the presence of test product was not less than 70% of that recovered from the inoculum control.

Step 3

In a Biological Safety Cabinet, two 2cm ² synthetic skin swatches were each pre-treated with 10pL of the test product at the RTU concentration. Each pair of skin swatches was rubbed together to distribute the test product, and dried under HEPA laminar air. The formulation remained on the swatches for sufficient time to demonstrate the residual efficacy of each test product. Duplicate tests were performed at each time point for all test products (including the reference product) and the water control.

Step 4 - (Water control - Baseline Control)

The synthetic skin swatches were also pre-treated with sterile water in the same manner as the test product, and tested at the same time points along-side the test product.

Step 5

At various time points, each treated skin swatch was inoculated with 10pL of culture suspension at an approximate concentration of 109 cfu/mL, and evenly distributed with a sterile 1 piL loop. An exposure time of 5 minutes was allowed prior to transferring the skin swatch into neutralising broth (TLT). The inoculated neutralising broth was mixed and serially diluted to aid in determining the number of viable bacteria remaining.

Step 7

Step 5 and 6 were followed to test the water control in the same manner as the test product.

Step 8

The neutralised solutions for the test products and the water control were serially diluted using 0.1% Peptone, and each dilution was plated in duplicate using Standard Plate Count Agar.

Step 9

The plates were incubated at 35°C ± 1°C for 48 hours.

The tests gave the results detailed below.

Results

Quantitative Suspension test for evaluating bactericidal activity

Methodology: EN13727

CFU = Colony Forming Unit

Nv is the number of cells per ml in the validation suspension.

A, B and C are the numbers of surviving cells in the experimental conditions control (A), neutralizer control (B) and method validation (C), at the end of the contact time

A, B & C should preferably be >50% the value of Nv.

By way of summary, (TMD 110, EN13727), Formulations A and B showed greater than 6 log reduction against S.aureus, E.coli, P.aeruginosa and E.hirae at 1 minute contact time.

Formulation C showed greater than 6 log reduction against E.coli, P.aeruginosa and E.hirae and greater than 5 log reduction against S.aureus at 1 Minute contact time. All three formulas resulted in a >99.99% reduction in microorganisms after 1 minute contact.

Results of Virucidal Test by Carrier Method Methodology: ASTM E1053

Note:

Presence of virus is presented in a X+ of 4 format i.e. X ⁺ /4: X ⁺ - number of wells (X) with presence of virus (+)

4 - total number of inoculated wells.

Example: In the event of a 3+/4 result, this indicates that 3 of the total 4 wells show a positive virus response.

Absence of virus in each response is recorded as “0”

Cytotoxic response is recorded as “C”

Calculated virus titre = 106.77TCID50/0.1 ml (6.77 Iog10)

Cell control - 4 wells with healthy cell monolayer

* The Reed & Muench LD50 Method was used for determining the virus titre endpoint.

To summarise the results (TMCV 006, ASTM E1053), regarding cytotoxicity and neutralisation, the Formulations A and B showed virucidal efficacy against MHV1 by achieving 3.44 log reduction in virus concentration after 1 minute’s exposure period at room temperature. The formulations C also showed virucidal efficacy against MHV1 by achieving 3.10 log reduction in virus concentration after 1 minute’s exposure period at room temperature. This indicates that each formulation results in >99.9% reduction in viral count after 1 minute contact time, with Formulas A and B exhibiting slightly better results than Formula C.

Results

The 24-hour Residual Anti-Microbiological Study of the Hand Disinfectant Product Methodology: The above Custom In-vitro Study Protocol

Summary of Residual Efficacy Results (Formulation A)

Summary of Residual Efficacy Results (Formulation B)

Summary of Residual Efficacy Results (Formulation C)

By way of summary, Formulation B (at RTU volume) demonstrated residual efficacy with log reduction of between 2.27 and >6.57 throughout the 24 hour’s period (at 5 mins, 30 mins, 1 hr, 2hr, 4hr, 6hr and 24hr) against Staphylococcus aureus NZRM 147 and Escherichia coli NZRM 2577. In comparison, Formulations A and C did not exhibit effective residual efficacy against either bacterial strain (maximum log reduction for either organism did not exceed 0.2 at any time point).

Formulation B demonstrated residual biocidal activity against both Staphylococcus aureus and Escherichia coli after 24 hours (4.93 and 2.46 log reduction, respectively). This translates to a >99.99% and >99% reduction in the count of Staphylococcus aureus and Escherichia coli, even if exposure to either organism occurs 24 hours after application of Formula B. Conversely, Formulation A exhibited a low log reduction against Staphylococcus aureus (0.02) after 24 hours, in addition to exhibiting a negative log reduction against Escherichia coli (-0.10), indicating growth of organism. Similarly, Formula e resulted in negative log reductions against both Staphylococcus aureus (-0.04) and Escherichia coli (- 0.12) after 24 hours, indicating organism growth.

This is significant as it indicates that Formula B exhibits residual efficacy against microorganisms on synthetic skin, even after significant time has passed following application of the formula. This is believed to be related to a synergistic interaction provided by the Benzylkonium and Organosilane ingredients in Formulation B. Other Forms of Benzlakonium

While preferred formulations according to the invention utilise Benzlakonium chloride, in other embodiments this may be substituted by other forms of Benzlakonium, for example Benzalkonium free base or one or more alternative Benzalkonium salts (e.g. Benzalkonium Bromide, Benzalkonium Saccharinate and Acesulfame Benzalkonium)-.— In each case the weight amounts would be adjusted to provide more or less equivalent function.

Other Organosilanes

Similarly, while preferred forms of the invention utilise 3-(trimethoxysilyl)propyl dimethyl octadecyl ammonium chloride, in other embodiments this may be substituted by other organosilanes, for example one or more of S-(trihydroxysilyl) propyl dimethyl octadecyl ammonium chloride (CAS 199111 -50-7) and n,n-dimethyl-n-[3-(trimethoxysilyl)propyl]-1- tetradecanaminium chloride (CAS 41591 -87-1 )- In each case the weight amounts would be adjusted to provide more or less equivalent function.

Preservatives, Humectants and Surfactants

Further, formulations according to the invention may use alternative preservative, humectant and/or surfactant materials to those of Formulations A, B and C, adjusting the weight amounts as appropriate to provide more less equivalent function. Examples of these are as follows -

In terms of disclosure, this document hereby discloses each item, feature or step mentioned herein in combination with one or more of any of the other item, feature or step disclosed herein, in each case regardless of whether such combination is claimed. While some preferred embodiments of the invention have been described by way of example it should be appreciated that modifications and improvements can occur without departing from the scope of the following claims.