Influence of Product Volume, Delivery Format, Alcohol Concentration on Dry-Time, Efficacy of ABHRs

Alcohol-based handrubs (ABHR) range in alcohol concentration from 60 percent to 95 percent and are available in a variety of delivery formats, such as rinses, gels, and foams. Recent studies suggest that some ABHR foams dry too slowly, thereby encouraging the use of inadequate volumes. This study by Macinga, et al. (2014) investigates the influence of product volume, delivery format, and alcohol concentration on dry-time and antimicrobial efficacy of ABHR foams, gels and rinses.

ABHR dry-times were measured using volunteers to determine the influences of product volume, delivery format, and alcohol concentration. ABHR efficacies were evaluated according to the European Standard for Hygienic Hand Disinfection (EN 1500) using 3-mL application volumes rubbed for 30 seconds, and additionally, using volumes of the products determined to rub dry in 30 seconds.

Volumes of six ABHR determined to rub dry in 30 seconds ranged from 1.7 mL to 2.1 mL, and the rate of drying varied significantly between products. ABHR dry-times increased linearly with application volume and decreased linearly with increasing alcohol concentration, but were not significantly influenced by product format. An ABHR foam (70% EtOH), rinse (80% EtOH), and gel (90% EtOH) each met EN 1500 efficacy requirements when tested at a volume of 3 mL, but failed when tested at volumes that dried in 30 seconds.

The researchers concluded that application volume is the primary driver of ABHR dry-time and efficacy, whereas delivery format does not significantly influence either. Although products with greater alcohol concentration dry more quickly, volumes required to meet EN 1500 can take longer than 30 seconds to dry, even when alcohol concentration is as high as 90 percent. They say that future studies are needed to better understand application volumes actually used by healthcare workers in practice, and to understand the clinical efficacy of ABHR at such volumes. Their research was published in BMC Infectious Diseases.

Reference: Macinga DR, Shumaker DJ, Werner HP, Edmonds SL, Leslie RA, Parker AE and Arbogast JW. The relative influences of product volume, delivery format and alcohol concentration on dry-time and efficacy of alcohol-based handrubs. BMC Infectious Diseases 2014, 14:511  doi:10.1186/1471-2334-14-511