Copyright 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Emetine is a potent antiviral that acts on many viruses in the low-nM range, with several
studies in animals and humans demonstrating antiviral activity. Historically, emetine was used to treat
patients with Spanish influenza, in the last stages of the pandemic in the early 1900s. Some of these
patients were "black" with cyanosis. Emetine rapidly reversed the cyanosis and other symptoms of
this disease in 12–24 h. However, emetine also has been shown to have anti-inflammatory properties
and it appears it is these anti-inflammatory properties that were responsible for the effects seen in
patients with Spanish influenza. Emetine, in the past, has also been used in 10s to 100s of millions of
people at a dose of ~60 mg daily to treat amoebiasis. Based on viral inhibition data we can calculate a
likely SARS-CoV2 antiviral dose of ~1/10th the amoebiasis dose, which should dramatically reduce
the risk of any side effects. While there are no anti-inflammatory dose response data available,
based on the potential mode of action, the anti-inflammatory actions may also occur at low doses.
This paper also examines the toxicity of emetine seen in clinical practice and that seen in the laboratory,
and discusses the methods of administration aimed at reducing side effects if higher doses were
found to be necessary. While emetine is a "pure drug" as it is extracted from ipecac, some of the
differences between emetine and ipecac are also discussed.