Fig.3: Comparison between drug inhalation and exhalation.
Looking for a molecule that meets the requirement to be eliminated via
the lung, we may search among monoterpenes, whose chemical and
pharmacological characterizations are well known. The 1,8-cineole
eucalyptol is the main monoterpene of the essential oil of eucalyptus.
The EMA community herbal monograph on eucalyptus essential oil has
established a dose regimen of 200 mg orally up to 5 times/day, and its
safety has been adequately assessed. It has been reported to have a
large spectrum of antimicrobial effect against several type of bacteria,
viruses and fungi, which is assumed to be a nonspecific pharmacological
effect given its phenolic chemical characteristics. A specific in
vitro investigation has highlighted the antiviral properties of an
aerosolized solution of eucalyptol on nebulized viruses (Usachevet al. , 2013), confirming the antiviral properties already
described (Astani et al., 2010). Furthermore, its anti-inflammatory
effect in the lung has been well characterized, and specific clinical
trials of its traditional use have highlighted its efficacy and safety
in asthmatic patients. All these pharmacological characteristics of this
monoterpene could make it a candidate to test for the treatment of
COVID-19, and its use as a prophylactic or when the viral load is
particularly low is also hypothesized. A further advantage is given by
the great flexibility of the molecule, which can be used both by
inhalation and orally. Another point to consider is the great
availability of different monoterpenes, of which 1,8 cineole can be
considered a representative, with similar characteristics that can be
taken into consideration in a more detailed scientific analysis and for
subsequent use in therapy.
The use of naturally derived substances in this particular emergency
situation is also reflected in recent clinical trials that focus on a
possible role of traditional Chinese medicine (TCM) in support of
standard therapy. Some Chinese guidelines have described the use of
traditional herbal medicine for prophylactic purposes (Jin et al.,
2020). Furthermore, the recent precious gift made by the People’s
Republic of China to Italy as emergency support contained TCM products
(Ansa, 2020).