60 HYGIENE
Formulating sanitiser quickly, easily and compliantly
n Russel Walters, PhD - Consultant
Hand sanitisers are designed to be an alternative to hand washing with water and surfactants — they reduce the viral and bacterial load on skin. While they do not necessarily kill everything, viruses, such as COVID-19, are more susceptible. With recent rule changes, it is now easy to begin formulation and manufacture of alcohol- based hand sanitisers. Here Dr Russel Walters, freelance scientist at Kolabtree, the freelance platform for scientists, shares his expertise on how to start manufacturing a hand sanitiser quickly, easily and compliantly. In order for a virus to infect a human
host, the host needs to be exposed to a sufficient viral load, typically hundreds, thousands or tens of thousands of viral particles. Hand sanitiser dramatically reduces the viral load on the skin, and therefore can reduce infections, or perhaps infection severity. Long sustained exposure to an infected
person is best for transmission. It is therefore important to sanitise the hands, because they are the primary contact with the outside world and can spread viral particles if they touch the eyes, mouth, food, etc. Hand sanitisers have repeatedly been shown to slow the spread of viruses. Hand sanitisers are regulated in most
countries. In the US, the FDA has recently liberalised manufacturing rules. This is a good thing for new hand sanitiser manufacturers and formulators. It opens a legal path for new manufacturers to expand into hand sanitiser supply, and it also makes formulation straightforward. Unlike skin lotions, the options are few and constraints clear. This article will focus on the two formulas
that are allowed by the FDA under the recent COVID-19 guidance.
The choice is yours Under the FDA, there are two possible formulas for hand sanitiser, ethanol or isopropanol. Before COVID, hand sanitisers were made by very large, FDA-registered drug manufacturers. Think Purell. However, in March 2020, the FDA issued
guidance for expanded production of hand sanitisers during COVID-19. The intention
PERSONAL CARE GLOBAL
was to increase production of hand sanitiser by opening up which entities could manufacture them beyond previously licensed or registered drug manufacturers. However, it is still very specific on the formula of hand sanitisers. The World Health Organization (WHO)
has released an excellent step by step guide to the local production of hand sanitizers. The two formula options that the WHO recommends are the same as in the FDA guidance and are explained below.
Ingredients According to the guidelines, the hand sanitisers must be manufactured using only the following ingredients; either ethanol or isopropanol, glycerin, hydrogen peroxide and sterile water. And that is it. Four ingredients, mix them with care, and you have a hand sanitiser ready for this new post-COVID-19 world. The proportion of ingredients is also
specified in volume per cent, but be aware of the difference between volume per cent and weight per cent. There is a big difference, because different ingredients have different densities. While water has a density of 1g/cm3
, ethanol has a density of 0.789g/cm3
Formula 1: Ethanol (volume %) Ethanol 80%; Glycerin 1.45%; Hydrogen peroxide 0.125%; QS water
.
Formula 2: Isopropanol (volume %) Isopropanol 75%; Glycerin 1.45%; Hydrogen peroxide 0.125%; QS water Note that most raw materials are not supplied as 100 per cent pure, single ingredients, they often contain some water. Ethanol is typically sourced as 95 per cent/5 per cent ethanol/water, or 190 proof. You need to factor the raw material composition into your calculations.
Fragrance Users tend to really like fragrances in skin care products, but in hand sanitisers these ingredients are not needed and will increase the raw material prices of your product. In skin care products, fragrances are often used to cover the underlying base odour, but this is unnecessary in hand sanitisers; their base odour is minimal. Under the FDA COVID hand sanitiser guidance, fragrances and skin benefit ingredients are explicitly not allowed.
Thickening hand sanitisers, increasing viscosity Hand sanitiser gels, like Purell, use polymers to increase the viscosity, which can add some significant complications in the manufacturing process. Thickening polymers are not part of the FDA formula described above, but you may want to read more about the different polymeric options
August 2020
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