26 HYGIENE
under the condition that the manufacturer would add an authorised denaturant like denatonium benzoate. Another example of an exemption was for bioethanol generally used as heating fuel, with the condition of respecting the specifications related to odour and impurity content. In order to boost the antimicrobial activity
of alcohol, many formulations included some additional antibacterial ingredients, such as quaternary ammonium compounds like benzalkonium chloride. Among other active substances, hydrogen peroxide was included as one of the ingredients required by the WHO in formulations of hydroalcoholic hand sanitising solutions, but mainly to inactivate contaminating bacterial spores in the solution rather than as an active substance for hand antisepsis.2
Other ingredients Due to the need for repeated application of these products and the dehydrating properties of the alcohol, many formulations include some additional ingredients that could help to care about the skin and to reduce hand dryness. Among the myriad of ingredients typically added to hand sanitising gels, polyols and vegetable extracts are the most popular. Glycerine, propanediol, butylene glycol
and propylene glycol are largely included as humectants, thus playing a double role: moisturising the skin, and improving texture, feel and the application of the gels. The most popular vegetable extracts are undoubtedly aloe vera and camomile, which are known for their soothing and healing properties; as well as tea tree oil and rosemary, known for their antimicrobial properties. Gel formulations are usually thickened with
combinations of polyacrylic acid (PAA), better known as carbomer or acrylate variants, such as acrylates/C10-30
alkyl acrylate crosspolymer,
with organic amines, such as triethanolamine or aminopropanol, as neutralising agents. This combination makes it possible to achieve crystal clear gels that typically break quickly during application as acrylates are not able to handle the residual salt in hands. Sodium hydroxide is the most traditional base used to neutralise and thicken acrylic-based crystal- clear gels, but it is not ideal in formulations containing a high level of alcohol. During the first months of the pandemic in
2020, there was a serious shortage of acrylic polymer, due to the sudden increase in demand for these raw materials. Therefore, many other options of polymers were investigated in order to guarantee a rapid availability of hydroalcoholic hand sanitising gels. Many different options of rheology modifiers
were investigated and used, such as other type of acrylate copolymers and also cellulosics. Cellulosics, such as hydroxypropylcellulose and hydroxyethylcellulose, are among the most commonly used. They are naturally derived and can thicken
alcohol-based formulations, as well as helping to create transparent gels with a different texture and imparting slip to the formulation. Cellulosic gels do not need to be neutralised
PERSONAL CARE March 2022
TABLE 1: DIFFERENT CLASSES OF INGREDIENTS IN HAND SANITISING FORMULATIONS Solution
Base ingredient Active substance
Water Alcohol (60-80%)
Other active substances Hydrogen peroxide quat salts Skin care ingredients
Viscosity agents Other ingredients Colourants, fragrance
and give a more substantive film on the skin after application as, unlike acrylates, they do not break in the hands upon rubbing. Some emollients have been used as well, with the aim of keeping the hands clean and nourished at the same time. Alcohol-soluble esters of α-hydroxy acids are popular due to their high polarity and ease of incorporation into such formulations. Examples of these emollients include lactate (like lauryl, myristyl or C12-15
alkyl lactate), diisopropyl adipate and
isodecyl neopentanoate.3 Among other ingredients, there are
fragrances, colourants and others, mainly related to the personalisation of the final product, in order to give a more appealing aspect and product experience. Selecting a fragrance for a hand sanitiser could be quite a challenge, as it is important to guarantee fragrance stability at a high level of alcohol content for the duration of the accelerated stability (typically three months at 40°C). In addition, the fragrance must cover the odour of the alcohol without being overwhelming, since the product could be applied more than ten times a day. Traditional dyes for cosmetic products can also be added to differentiate the aspect of a product that is usually available as a colourless clear gel. As different formats were being offered to the customers, the introduction of suspended capsules was also observed. This helped to add an extra element of skin care to the hand sanitising gel, as the capsules contained vegetable oils or vitamins.
Claims & regulatory restrictions From a regulatory point of view, a formula recipe could enter the market as a cosmetic or registered as a biocide. The criteria that would
Polyol extracts, alcohol-soluble esters
Water
Alcohol (60-80%) Quat salts
Polyol extracts, alcohol-soluble esters
Polyacrylic acid (paa) + organic amines acrylates + organic amines cellulosics
Colourants, fragrance, suspended particles
define the product under cosmetic or biocidal regulations includes the function, the way it is presented and the claims made. If a product falls under the scope of the BPR, a pre-sale authorisation and registration is required either at EU level or with the national authorities. This also means a more costly and longer time to market. For an antibacterial product to be
considered as a cosmetic, it must have a cosmetic primary function, such as cleansing, moisturising, protecting or perfuming skin. The antibacterial claim has to be a secondary claim and this fact must be made clear by the way it is presented on pack. Reference to claims such as ‘kills x% of bacteria’ and ‘disinfectant’ are not allowed under the Cosmetic Products Regulation.4,5,6 Whether the product is classified as a
cosmetic or a biocide, it is paramount to guarantee its efficacy, safety and quality. The most important factor is to achieve an efficacious antimicrobial product. For a hydroalcoholic hand sanitiser
sold as a cosmetic, it is not necessarily a requirement to perform any specific test on the antimicrobial performance, bearing in mind the permitted claims. As long as the formulation contains alcohol in a quantity between 60- 80% v/v for the whole shelf-life of the product, the manufacturer can guarantee that the product is effective. For hand sanitisers sold as biocidal
products, the requirements are very different and proven efficacy results are mandatory. Additionally, the type of test and protocols are already established following the European standard test methods (EN 1500, EN 1276, EN 1650, to name a few). Finally, the laboratories performing the test must be GLP-certified.
www.personalcaremagazine.com
Gel
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84
