Cetylpyridinium Chloride (CPC) Exhibits Potent, Rapid Activity Against Influenza Viruses in vitro and in vivo

Abstract

Background There is a continued need for strategies to prevent influenza. While cetylpyridinium chloride (CPC), a broad-spectrum antimicrobial agent, has an extensive antimicrobial spectrum, its ability to affect respiratory viruses has not been studied in detail. Objectives Here, we evaluate the ability of CPC to disrupt influenza viruses in vitro and in vivo. Methods The virucidal activity of CPC was evaluated against susceptible and oseltamivir-resistant strains of influenza viruses. The effective virucidal concentration (EC) of CPC was determined using a hemagglutination assay and tissue culture infective dose assay. The effect of CPC on viral envelope morphology and ultrastructure was evaluated using transmission electron microscopy (TEM). The ability of influenza virus to develop resistance was evaluated after multiple passaging in sub-inhibitory concentrations of CPC. Finally, the efficacy of CPC in formulation to prevent and treat influenza infection was evaluated using the PR8 murine influenza model. Results The virucidal effect of CPC occurred within 10 minutes, with mean EC50 and EC2log ranging between 5 to 20 μg/mL, for most strains of influenza tested regardless of type and resistance to oseltamivir. Examinations using TEM showed that CPC disrupted the integrity of the viral envelope and its morphology. Influenza viruses demonstrated no resistance to CPC despite prolonged exposure. Treated mice exhibited significantly increased survival and maintained body weight compared to untreated mice. Conclusions The antimicrobial agent CPC possesses virucidal activity against susceptible and resistant strains of influenza virus by targeting and disrupting the viral envelope. Substantial virucidal activity is seen even at very low concentrations of CPC without development of resistance. Moreover, CPC in formulation reduces influenza-associated mortality and morbidity in vivo.

In vitroassessment of the virucidal activity of four mouthwashes containing Cetylpyridinium Chloride, ethanol, zinc and a mix of enzyme and proteins against a human coronavirus

“…Against a SARS COV2 surrogate HCoV-229E, at relevant in use contact times, only the 0.07% CPC mouthwash proved to be effective in reducing viral count by greater than 99.9%. Though preliminary, this result agrees with evidence of CPC activity against influenza virus and a recently published clinical trial with COVID-19 patients, where a 0.075% CPC containing mouthwash was reported to reduce saliva viral load for up to 6 hours after use 9,14 . Contact with the mouthwash containing 15.7% ethanol did not lead to significant reduction in count, and given alcohol levels of 60% -95% v/v are used in hand hygiene products, it seems likely that a mouthwash will require a higher concentration of ethanol or combination of agents to bring about a reduction in viral load 15 .…”

“…In this study, we compared four anti-bacterial mouthwashes containing actives hypothesised to act against enveloped viruses. CPC is a quaternary ammonium compound which interacts with the viral envelope through cationic charge-based interaction leading to gross distortion of the viral ultrastructure 9 . Similarly, alcohols including ethanol, perturb the lipid membrane leading to leakage 7 .…”

Use of mouthwashes against COVID-19 in dentistry

“…33 The antiviral effect of CPC has been demonstrated in influenza patients, significantly reducing the duration and severity of cough and sore throat. 31,34 Hypotheses about a possible action over SARS-CoV-2 are based on its lysosomotropic mechanism of action and its ability to destroy viral capsids. 35 These findings indicate that CPC could be effective against other enveloped viruses such as coronaviruses.…”

Experimental Dissection of the Lytic Replication Cycles of Herpes Simplex Viruses in vitro

“…Virucides are antiviral compounds that can interfere directly with viral infectivity of the virion by altering their structure or components (Suazo et al, 2015b ). Although their mechanism of action is seldom studied at the molecular level, some of these compounds interfere with the lipid envelope of HSVs, which can be evidenced by transmission electron microscopy (TEM) (Popkin et al, 2017 ). Interestingly, numerous compounds with virucidal activity have been identified both, derived from natural and non-natural sources (Schuhmacher et al, 2003 ; Schnitzler et al, 2007 ; Bultmann et al, 2010 ; Houston et al, 2017 ; Pradhan and Nguyen, 2018 ).…”