Is Benzalkonium Chloride (BAK) an Effective Antiviral against Adenovirus?

Abstract

Purpose : Benzalkonium chloride (BAK) is a common preservative used in ophthalmic medications and is the active ingredient in some skin disinfectants and hand sanitizers. BAK is known to be effective in killing bacteria and enveloped viruses. However, its activity against non-enveloped viruses is unknown. The goal of the current study was to determine whether BAK, at concentrations contained in ophthalmic medications, skin disinfectants and hand sanitizers, is effective in reducing titers of common ocular types of non-enveloped adenovirus (Ad) in vitro.

Methods : The direct in vitro inactivating activity of BAK was determined in duplicate trials by incubating high titer stocks of clinical isolates of Ad3, Ad4, Ad5, Ad7a, Ad8, Ad19, and the ATCC reference Ad37 isolate with BAK concentrations of 0.001%, 0.003%, 0.005%, 0.01% (concentrations found in ophthalmic medications), 0.1% (concentration found in skin disinfectants and hand sanitizers), and 0% (control media) for 1h at 33^oC. Following incubation, standard plaque assays were performed on the reaction mixtures to determine the adenovirus titers after BAK or control treatment. Adenovirus titers were Log₁₀ converted and Log₁₀ reductions in titers from the control were calculated. Decreases in titers of ≥ 3 Log₁₀ were considered virucidal while decreases in titers of < 1 Log₁₀ were considered ineffective.

Results : A BAK concentration of 0.1% was virucidal for Ad3, Ad5, Ad7a, Ad19, and Ad37. 0.1% BAK reduced titers >1 Log₁₀ but < 3 Log₁₀ for Ad4 and Ad8. A >1 Log₁₀ decrease in titers was demonstrated for BAK concentrations of 0.003%, 0.005% and 0.01% for Ad5 only. Decreases in titers for the other adenovirus types for those concentrations were ≤ 0.53 Log₁₀. 0.001% BAK produced decreases in titers of ≤ 0.17 Log₁₀ for all adenovirus types.

Conclusions : BAK, at concentrations used in common ophthalmic medications, demonstrated variable efficacy in reducing titers of the adenovirus types tested. However, 0.1% BAK was effective in reducing titers of all of the adenovirus types tested. BAK, at concentrations used in common ophthalmic medications, was not consistently effective as an agent against adenovirus, but higher concentrations should be further investigated as a topical treatment for adenoviral ocular infections, as long as ocular toxicity is not an issue.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.