Oleander Extract for COVID-19? That's a Hard 'No' Experts Say

Megan Brooks

August 19, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Oleandrin, a toxic cardiac glycoside found in the poisonous oleander plant, is making headlines as a potential treatment for COVID-19, raising concerns that uninformed people may eat the leaves of the plant and become ill or die.

"Though renowned for its beauty and use in landscaping, this Mediterranean shrub is responsible for cases of accidental poisoning across the globe. All parts of the plant are poisonous," Cassandra Quave, PhD, ethnobotanist and herbarium curator at Emory University, Atlanta, Georgia, cautioned in an article in The Conversation, an independent, not-for-profit publication.

Oleandrin has properties similar to digoxin; the onset of toxicity occurs several hours after consumption.

The first symptoms of oleandrin poisoning may be gastrointestinal, such as nausea, vomiting, abdominal pain, diarrhea (which may contain blood), and loss of appetite.

After these first symptoms, the heart may be affected by tachyarrhythmia, bradyarrhythmia, premature ventricular contractions, or atrioventricular blockage. Xanthopsia (yellow vision), a burning sensation in the eyes, paralysis of the gastrointestinal tract, and respiratory symptoms may also occur.

Oleandrin poisoning may affect the central nervous system, as evidenced by drowsiness, tremors, seizures, collapse, and coma leading to death. When applied to the skin, oleander sap can cause skin irritations and allergic reactions characterized by dermatitis.

Diagnosis of oleandrin poisoning is mainly made on the basis of a description of the plant, how much of it was ingested, how much time has elapsed since ingestion, and symptoms. Confirmation of oleandrin in blood involves fluorescence polarization immunoassay, digoxin immunoassay, or liquid chromatography-electrospray tandem mass spectrometry.

Neither oleander nor oleandrin is approved by regulatory agencies as a prescription drug or dietary supplement.

In Vitro Study

Oleandrin for COVID-19 made headlines after President Trump met in the Oval Office with Andrew Whitney, vice chairman and director of Phoenix Biotechnology, along with Housing and Urban Development Secretary Ben Carson, MD, and MyPillow founder/CEO Mike Lindell, a strong supporter of Trump and an investor in the biotech company, to learn about oleandrin, which Whitney called a "cure" for COVID-19, Axios reported.

In an in vitro study, researchers from Phoenix Biotechnology and the University of Texas Medical Branch, Galveston, tested oleandrin against SARS-CoV-2 in cultured Vero cells.

"When administered both before and after virus infection, nanogram doses of oleandrin significantly inhibited replication by 45 to 3000-fold," the researchers said in an article posted on bioRxiv, a free online archive and distribution service for unpublished preprints in the life sciences. The study has not been peer reviewed.

On the basis of these in vitro findings, the researchers said the plant extract has "potential to prevent disease and virus spread in persons recently exposed to SARS-CoV-2, as well as to prevent severe disease in persons at high risk."

But it's a far cry from test tube to human, one expert cautioned.

"This is an understatement: Care must be taken when inferring potential therapeutic benefits from in vitro antiviral effects," Harlan Krumholz, MD, cardiologist and director, Yale New Haven Hospital Center for Outcomes Research and Evaluation, New Haven, Connecticut, told Medscape Medical News.

"There is a chasm between a single in vitro study and any use in humans outside of a protocol. People should be cautioned about that distance and the need [to] avoid such remedies unless part of a credible research project," said Krumholz.

Yet Lindell told Axios that, in the Oval Office meeting, Trump expressed enthusiasm for the US Food and Drug Administration to allow oleandrin to be marketed as a dietary supplement or approved for COVID-19.

"This is really just nonsense and a distraction," Jonathan Reiner, MD, of George Washington University Medical Center, Washington, DC, said on CNN.

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