Revisiting COVID-19 and Chemicals for Making Hand Antiseptics
23 May 2021
Ezekiel O. Akinkunmi and Abdulsalam Mahmud
The advent of COVID-19 has awakened the culture of using hand sanitizers in Nigeria. As a result, the public domain is saturated with different kinds of hand-hygiene products.
Unfortunately, these products are from various sources, contain all kinds of chemicals, and most of them did not even pass through the regulatory agencies to ascertain their quality, just as some of the manufacturers also did not adhere to necessary guidelines before offering their products for sale to the general public.
The hand is a major medium by which microbial infectious agents including bacteria and viruses are transferred from one part of the body to another and from person to person, both in the hospital and the communities. Hand hygiene is thus one of the core elements of infection control measures and it has been proven to effectively reduce the incidence of infections.
Hand hygiene products are preparations designed for the purpose of reducing or eliminating germs in the hands, and thus preventing the transmission of agents of infectious diseases through the hands. The two main categories of hand-hygiene products recommended by the World Health Organization are soaps and products containing chemical antimicrobial agents.
Soaps are made of compounds of natural oils or fats with sodium hydroxide or another strong alkali. They are salts of fatty acids used in cleansing. Since they are salts of fatty acids, soaps have the general formula (RCO2-)nMn+ where R is an alkyl, M is a metal and n is the charge of the cation.
In cases where the Metal is Sodium (Na) or Potassium (K), the soaps are called toilet soaps and are the type used for handwashing. In handwashing, when lathered with water, soap kills microorganisms by disorganizing their membrane lipids bilayer and denaturing their proteins.
Soap also causes the emulsification of oils, enabling them to be carried away by running water. Humans have used soaps over thousands of years. Potassium soaps are more soluble in water than sodium soaps.
Hence Potassium soaps in concentrated form are called soft/liquid soap. Potassium soaps require less water to liquefy because of their softness and greater solubility; thus can contain more cleaning agent than liquefied sodium soap and can be used as shampoos and shaving creams, for cleaning of dirty floors and cooking utensils, and in emulsion polymerization processes used in rubber and plastic industries.
Antimicrobial agent preparations that are meant for the elimination of infectious agents on human tissues and mucous membranes are called antiseptics. Thus, antimicrobial hand-hygiene products fall into the categories of antiseptics.
Products used in hand hygiene contain antimicrobial chemical agents that exhibit either bactericidal or bacteriostatic properties depending on the concentrations and the nature of those agents. When an agent acts only by preventing the multiplication of disease-causing germs, the action is said to be bacteriostatic.
On the other hand, when the agent acts by directly killing the germs, the action is referred to as bactericidal. Before a compound is taken as an antiseptic, it must have certain properties. The first is that it should not be toxic to human cells and tissues.
Again, the active chemicals must have a high level of compatibility with other ingredients in the product as well as with the packaging materials including the containers, covers and labels. Also, the products must not have deleterious odour, colour and other aesthetics. Finally, the product must be cheap and reasonably affordable to the user.
The six chemical groups that are used as antiseptics include Alcohols, Phenolics, Chlorhexidine Gluconate, Quaternary Ammonium Compounds, Iodine and Triclosan.
Products containing alcohols are the most widely used hand antiseptics. Alcohols exhibit rapid broad-spectrum antimicrobial activity against vegetative bacteria (including mycobacteria), viruses, and fungi but are not sporicidal.
Alcohol in hand sanitizers disinfects hands by penetrating the cell membranes of pathogens, dehydrating the cell and denaturing proteins.
Alcohol-based hand sanitizers provide an alternative measure for hand hygiene and are preferred over hand washing, because of the mobility and convenience they offer.
The second group of antiseptic products are those that contain the phenolics.
They possess antibacterial, antifungal and antiviral properties. Examples of phenolics are cresol which is contained in commercial preparation like Lysol soap, and chloroxylenol contained in Dettol.
Quaternary Ammonium Compounds
The Quaternary ammonium compounds are the next category of chemical agents found in hand-hygiene products. They are called QACs by abbreviations.
Examples of the QACs include benzalkonium chloride, benzethonium chloride and cetrimide.
Chlorhexidine gluconate is another chemical agent used for making hand-hygiene products. It is probably the most widely used antiseptic found in antiseptic products.
Chlorhexidine has similar mechanisms of action to the phenolics and it is commonly formulated in combination with the QACs.
The next group of chemical agents used in making hand-hygiene products are the halogens. The halogen of main applications in this case is iodine and its products.
The products of other halogens such as chlorine, bromine and fluorine have been found to be highly reactive and toxic. Iodine kills germs very fast and it is active against most disease-causing microbes including bacteria, fungi, viruses and spores.
Triclosan is the last category of agents in hand-hygiene products that will be discussed in this write-up. It is a non-ionic, colourless substance. It is poorly soluble in water, but dissolves well in alcohols.
Similar to chlorhexidine, triclosan has persistent activity on the skin. Its activity in hand-care products is affected by pH, the presence of surfactants or humectants, and the ionic nature of the particular formulates.
It is hoped that hand sanitizers’ manufacturer will not compromise quality while producing their hand-hygiene products.
At a time when Coronavirus is still ‘ravaging’ the global population, we need quality and effective hand-hygiene products not only to protect us from contracting COVID-19, but also ward off other diseases, which can easily attack us.
Akinkunmi, PhD, a don in the Department of Pharmaceutics, Obafemi Awolowo University (OAU), in Ile-Ife; and Mahmud, a freelance journalist, are Fellows of the African Science Literacy Network (ASLN).
The fund for this paper was provided by African Science Literacy Network.