Dental Asia September/October 2021

Trends
Compound
Contact
Time
Cytotoxicity a
Neut.
Ctrl b
Virus
Titer C
VC
Titer c
LRV d
OSI-20210203A 5 min 1/10 None 3.0
OSI-20210203B 5 min 1/10 None 3.0
a Cytotoxicity indicates the highest dilution of the endpoint titer where full (80-100%) cytotoxicity was observed
b Neutralisation control indicates the highest dilution of the endpoint titer where compound inhibited virus CPE in the wells after neutralisation
(ignored for calculation of virus titer and LRV)
c Virus titer of test sample or virus control (VC) in log10 CCID50 of virus per 0.1mL
d LRV (log reduction value) is the reduction of virus in test sample compared to the virus control
Table 2: Virucidal efficacy against SARS-CoV-2 after contact with virus at 22 ± 2°C
Fig. 3: Nasal and oral sprays function as
supplementary layers of protection (in
addition to face masks) to short circuit cold
and flu viruses
to assist in preventing the onset
of infection caused by rhinovirus/
coronavirus/influenza virus by creating
a physical barrier to viral and bacterial
adhesion at the nasal and throat
mucosal membranes.
Oral Science International (Brossard,
Canada) has a unique formulation,
Cold & Flu Guard TM (Fig. 1), that unites
bioflavonoids with the mucosal
barrier. Glycerin and hyaluronic acid
components form a barrier/film over
the mucous membrane, and act as a
delivery method for the bioflavonoids
and menthol.
FLAVOBAC EFFICACY VS
RESPIRATORY VIRUSES
In vitro efficacy studies of Flavobac
aqueous solutions have demonstrated
concentration-dependent activity
against a range of bacterial, fungal
and protozoal pathogens 11 . Antiviral
studies have confirmed activity against
various viruses 12-14 . Retroscreen
Virology Laboratories (now hVIVO,
London, United Kingdom) and
Biobest Laboratories (Edinburgh,
United Kingdom) have independently
demonstrated that Flavobac
formulations are efficacious in the
inactivation of two different subtypes
of Influenza A: H5N1 (Bird Flu) and H1N1
(Swine Flu) 13,15 .
In 2004, Retroscreen Virology Ltd.,
Barts, and The London Queen Mary’s
School of Medicine and Dentistry,
evaluated the viricidal activity of
Flavobac against Urbani SARS virus,
Influenza A virus, Human Rhinovirus
and HIV. The results demonstrated
significant viricidal activity against all
the viruses at all concentrations and
time-points 14 .
The first anti-SARS-CoV-2 evaluation
of an oral spray formulation containing
Flavobac as the sole active ingredient
(developed specifically for routine
intranasal or intraoral use) was reported
in March 2021 by the Institute for
Antiviral Research (IAR) at the Utah
State University (Logan, Utah, United
States) [*data pending publication].
The IAR employs recognised scientists
to identify antiviral agents and vaccines
against a wide range of human
pathogenic viruses and has participated
in the pre-clinical development of
numerous FDA-approved antiviral
compounds.
Test compounds: Nasal and oral rinse
antiseptic solutions (Fig. 2) consisting
of aqueous Flavobac BCL concentrate
as the sole active ingredient and
OSI2021003 oropharyngeal spray
solution and other natural ingredients
were supplied by Oral Science
International.
Results: Flavobac aqueous solution
reduced SARS-CoV-2 titer below the
limits of detection at all concentrations
tested (Table 1). These results generate
dose optimisation and guide product
dosage and concentrations.
After incubation with Flavobac
commercial solutions OSI-20210203A
and OSI-20210203B, SARS-CoV-2 virus
titers and LRV were reduced below
the limits of detection (LRV>3.0) (Table
2). Each Flavobac containing solution
evaluated was effective at reducing
>3 log10 CCID50 infectious virus, from
4.7 log10 CCID50/0.1 mL to 1.7 log10
CCID50/0.1 mL or less (Table 2). This
represents a >99.9% efficacy of viral
reduction.
RELEVANCE
The challenge in developing oral and
nasal sprays is to create effective
topical preparations that are safe
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DENTAL ASIA SEPTEMBER / OCTOBER 2021