Alcohol-Based Hand Sanitizers: Does Gelling Agent Really Matter?

Ivana D’Angelo,Ettore Florio,Giuseppe Mantova,Mariateresa Vitiello,Elena Scaglione,Fabiana Quaglia,Chiara Pagliuca,Francesca Ungaro,Agnese Miro,Roberta Colicchio,Paola Salvatore,Romina Provenzano

doi:10.3390/gels8020087

Abstract

Hand hygiene, social distancing, and face covering are considered the first protection against Coronavirus spreading. The high demand during the COVID-19 emergency has driven a frenetic production and marketing of hand sanitizer gels. Nevertheless, the effect of the gelling agent and its amount on the effectiveness of alcohol-based hand sanitizers (ABHSs) needs to be clarified. We presented a systematic study on the effect of the characteristics and concentration of the most employed excipients on the properties and antimicrobial activity of ABHSs. Three different gelling agents, carbopol, hydroxypropylmethylcellulose (HPMC), and hydroxyethylcellulose (HEC), at four different concentrations were used to prepare ABHSs. Viscosity, spreadability, delivery from commercial dispensers, evaporation rate, rubbing time, and hand distribution of the ABHSs were then explored. Biocidal activity of selected ABHSs was evaluated in vitro on ATCC and clinical strains. The studied ABHS can be considered bioactive and comfortable. Nevertheless, the cellulose polymers and ethanol interactions led to a slight but significant reduction in the biocidal activity compared with carbopol-based formulations. Our results underline the importance of the gelling agent properties and support the choice of carbopol as one of the best thickener agents in ABHS formulations.

Highlights

Hand hygiene is considered one of the most effective strategies in preventing the transmission of microorganisms and virus infection across the public, healthcare workers, and from people to food [1,2], especially since January 2020, when the world was hit by the pandemic related to Coronavirus Disease-2019 (COVID-19)
V/v), we highlighted that the gelling agent type and its concentration are both relevant in formulation handling and biocidal activity
HPMC showed a very similar behavior when dispersed in a hydro-alcoholic medium, and an increase in ethanol evaporation rate was observed by increasing the cellulose derivative amount

Summary

Introduction

Hand hygiene is considered one of the most effective strategies in preventing the transmission of microorganisms and virus infection across the public, healthcare workers, and from people to food [1,2], especially since January 2020, when the world was hit by the pandemic related to Coronavirus Disease-2019 (COVID-19). Recommendations, hand hygiene, social distancing, and face covering have been considered the first protection against SARS coronavirus 2 (SARS-CoV-2) spreading during the last months. As reported by the World Health Organization (WHO), hand hygiene can be achieved by (i) handwashing with plain or antimicrobial soap and water, or by (ii) hand rubbing with waterless hand sanitizers [3]. Handwashing is considered the first line of defense against spreading infection [4,5], hand sanitizers have showed significant virucidal activity against SARS-CoV-2 [6,7]. Alcohol-based hand sanitizers (ABHS) are the most employed and recommended by the authorities

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