August 02, 2021

How to make hand sanitiser! 🧴🦠😷

To help countries and health-care facilities to achieve system change and adopt alcohol-based handrubs as the gold standard for hand hygiene in health care, WHO has identified formulations for their local preparation. Logistic, economic, safety, and cultural and religious factors have all been carefully considered by WHO before recommending such formulations for use worldwide (see also Part I, Section 14).

At present, alcohol-based handrubs are the only known means for rapidly and effectively inactivating a wide array of potentially harmful microorganisms on hands.⁶⁰^,²²¹^,³²⁹^,⁴⁸⁴^–⁴⁸⁷

WHO recommends alcohol-based handrubs based on the following factors:

evidence-based, intrinsic advantages of fast-acting and broad-spectrum microbicidal activity with a minimal risk of generating resistance to antimicrobial agents;
suitability for use in resource-limited or remote areas with lack of accessibility to sinks or other facilities for hand hygiene (including clean water, towels, etc.);
capacity to promote improved compliance with hand hygiene by making the process faster and more convenient;
economic benefit by reducing annual costs for hand hygiene, representing approximately 1% of extra-costs generated by HCAI (see also Part III, Section 3);⁴⁸⁸^–⁴⁹⁰
minimization of risks from adverse events because of increased safety associated with better acceptability and tolerance than other products (see also Part I, Section 14).⁴⁹¹^–⁴⁹⁸

For optimal compliance with hand hygiene, handrubs should be readily available, either through dispensers close to the point of care or in small bottles for on-person carriage.³³⁵^,⁴⁸⁵

Health-care settings currently using commercially-available handrubs should continue to use them, provided that they meet recognized standards for microbicidal efficacy (ASTM or EN standards) and are well accepted/tolerated by HCWs (see also Implementation Toolkit available at http://www.who.int/gpsc/en/). It is obvious that these products should be regarded as acceptable, even if their contents differ from those of the WHO-recommended formulations described below. WHO recommends the local production of the following formulations as an alternative when suitable commercial products are either unavailable or too costly.

12.1.1. Suggested composition of alcohol-based handrub formulations for local production

The choice of components for the WHO-recommended handrub formulations takes into account cost constraints and microbicidal activity. The following two formulations are recommended for local production with a maximum of 50 litres per lot to ensure safety in production and storage.

Formulation I

To produce final concentrations of ethanol 80% v/v, glycerol 1.45% v/v, hydrogen peroxide (H₂O₂) 0.125% v/v.

Pour into a 1000 ml graduated flask:

ethanol 96% v/v, 833.3 ml
H₂O₂ 3%, 41.7 ml
glycerol 98%,14.5 ml

Top up the flask to 1000 ml with distilled water or water that has been boiled and cooled; shake the flask gently to mix the content.

Formulation II

To produce final concentrations of isopropyl alcohol 75% v/v, glycerol 1.45% v/v, hydrogen peroxide 0.125% v/v:

Pour into a 1000 ml graduated flask:

isopropyl alcohol (with a purity of 99.8%), 751.5 ml
H₂O₂ 3%, 41.7 ml
glycerol 98%, 14.5 ml

Top up the flask to 1000 ml with distilled water or water that has been boiled and cooled; shake the flask gently to mix the content.

Only pharmacopoeial quality reagents should be used (e.g. The International Pharmacopoeia) and not technical grade products.

12.1.2. Method for local production

12.1.2.1. Volume of production, containers

10-litre preparations: glass or plastic bottles with screwthreaded stoppers can be used.
50-litre preparations: large plastic (preferably polypropylene, translucent enough to see the liquid level) or stainless steel tanks with an 80 to100 litre capacity should be used to allow for mixing without overflowing.

The tanks should be calibrated for the ethanol/isopropyl alcohol volumes and for the final volumes of either 10 or 50 litres. It is best to mark plastic tanks on the outside and stainless steel ones on the inside.

12.1.2.2. Preparation

The alcohol for the chosen formulation is poured into the large bottle or tank up to the graduated mark.
H₂O₂ is added using the measuring cylinder.
Glycerol is added using a measuring cylinder. As the glycerol is very viscous and sticks to the walls of the measuring cylinder, it can be rinsed with some sterile distilled or cold boiled water to be added and then emptied into the bottle/tank.
The bottle/tank is then topped up to the corresponding mark of the volume (10-litre or 50-litre) to be prepared with the remainder of the distilled or cold, boiled water.
The lid or the screw cap is placed on the bottle/tank immediately after mixing to prevent evaporation.
The solution is mixed by gently shaking the recipient where appropriate (small quantities),or by using a wooden, plastic or metallic paddle. Electric mixers should not be used unless “EX” protected because of the danger of explosion.
After mixing, the solution is immediately divided into smaller containers (e.g. 1000, 500 or 100 ml plastic bottles). The bottles should be kept in quarantine for 72 hours. This allows time for any spores present in the alcohol or the new or re-used bottles to be eliminated by H₂O₂.

12.1.2.3. Quality control

If concentrated alcohol is obtained from local production, verify the alcohol concentration and make the necessary adjustments in volume to obtain the final recommended concentration. An alcoholmeter can be used to control the alcohol concentration of the final use solution; H₂O₂ concentration can be measured by titrimetry (oxydo-reduction reaction by iodine in acidic conditions). A higher level quality control can be performed using gas chromatography⁴⁹⁹and the titrimetric method to control the alcohol and the hydrogen peroxide content, respectively. Moreover, the absence of microbial contamination (including spores) can be checked by filtration, according to the European Pharmacopeia specifications.⁵⁰⁰

For more detailed guidance on production and quality control of both formulations, see the “WHO-recommended hand antisepsis formulation - guide to local production” (Implementation Toolkit available at http://www.who.int/gpsc/en/).

12.1.2.4. Labelling of the bottles

The bottles should be labelled in accordance with national guidelines. Labels should include the following:

Name of institution
Date of production and batch number
Composition: ethanol or isopropanol, glycerol and hydrogen peroxide (% v/v can also be indicated) and the following statements:
WHO-recommended handrub formulation
For external use only
Avoid contact with eyes
Keep out of reach of children
Use: apply a palmful of alcohol-based handrub and cover all surfaces of the hands. Rub hands until dry. Flammable: keep away from flame and heat.

12.1.2.5. H₂O₂

While alcohol is the active component in the formulations, certain aspects of other components should be respected. All raw materials used should be preferably free of viable bacterial spores. The low concentration of H₂O₂ is incorporated in the formulations to help eliminate contaminating spores in the bulk solutions and excipients⁵⁰¹^,⁵⁰²and is not an active substance for hand antisepsis. While the use of H₂O₂ adds an important safety aspect, the use of 3–6% of H₂O₂ for the production might be complicated by its corrosive nature and by difficult procurement in some countries. Further investigation is needed to assess H₂O₂ availability in different countries as well as the possibility of using a stock solution with a lower concentration.

12.1.2.6. Glycerol

Glycerol is added to the formulation as a humectant to increase the acceptability of the product. Other humectants or emollients may be used for skin care, provided that they are affordable, available locally, miscible (mixable) in water and alcohol, non-toxic, and hypoallergenic. Glycerol has been chosen because it is safe and relatively inexpensive. Lowering the percentage of glycerol may be considered to further reduce stickiness of the handrub.

12.1.2.7. Other additives to the formulations

It is strongly recommended that no ingredients other than those specified here be added to the formulations. In the case of any additions, full justification must be provided together with documented safety of the additive, its compatibility with the other ingredients, and all relevant details should be given on the product label.

In general, it is not recommended to add any bittering agents to reduce the risk of ingestion of the handrubs. Nevertheless, in exceptional cases where the risk of ingestion might be very high (paediatric or confused patients), substances such as methylethylketone and denatonium benzoate⁵⁰³) may be added to some household products to make them less palatable and thus reduce the risk of accidental or deliberate ingestion. However, there is no published information on the compatibility and deterrent potential of such chemicals when used in alcohol-based handrubs to discourage their abuse. It is important to note that such additives may make the products toxic and add to production costs. In addition, the bitter taste may be transferred from hands to food being handled by individuals using handrubs containing such agents. Therefore, compatibility and suitability, as well as cost, must be carefully considered before deciding on the use of such bittering agents.

A colorant may be incorporated to differentiate the handrub from other fluids as long as such an additive is safe and compatible with the essential components of the handrubs (see also Part I, Section 11.3). However, the H₂O₂ in the handrubs may tend to fade any colouring agent used and prior testing is recommended.

No data are available to assess the suitability of adding gelling agents to the WHO-recommended liquid formulations, but this could increase potentially both production difficulties and costs, and may compromise antimicrobial efficacy.²⁰³^,³²⁵

The addition of fragrances is not recommended because of the risk of allergic reactions.

All handrub containers must be labelled in accordance with national/international guidelines.

To further reduce the risk of abuse and to respect cultural and religious sensitivities, product containers may be labelled simply as “antimicrobial handrubs” (see Part I, Section 17.4).

12.1.2.8. Use of proper water for the preparation of the formulations

While sterile distilled water is preferred for making the formulations, boiled and cooled tap water may also be used as long as it is free of visible particules.