An existing anti-lice medication has proven effective in lab tests as a Covid-19 killing treatment. Photo: AFP

Health authorities have warned against self-medicating for Covid-19 after shops reported a rush to buy the anti-parasitic drug ivermectin, which has proved effective in destroying the virus in Australian laboratory tests.

Researchers at Monash University in Melbourne reported to the online journal Antiviral Research that they infected cells with Sars-CoV-2, the coronavirus that causes Covid-19, and then exposed them to ivermectin.

“We showed that a single dose of ivermectin could kill Covid-19 in a petri dish within 48 hours, indicating potent antiviral activity,” said David Jans, a professor of biochemistry and molecular biology at the university.

Levels of the virus declined by 99.8% in 48 hours and completely within three days. There was even a “significant reduction” within 24 hours.

“The main way we think ivermectin works is to target a key molecule of our cells that we think helps the virus to proliferate,” Jans said. “By stopping this, the virus replicates more slowly, and so our immune system has a better chance to mount the antiviral response and kill the virus.”

Usually marketed under the name Stromectol, ivermectin was developed as a veterinary drug in the 1970s but is now used to treat head lice. It is also effective against parasites that cause other infections, like scabies.

A package of Stromectol branded ivermectin pills. Photo: Facebook

As it was originally developed for animals, the drug is designed to attack multicellular roundworms, which it kills by binding to their muscles and nerve cells, causing paralysis and death.

But scientists believe ivermectin may also target a specific protein common to many ribonucleic acid (RNA) viruses, as it has been effective against influenza and the West Nile virus.

Thai researchers recently tested it on dengue fever in laboratory trials, but it did not show any clinical benefits. Dengue is caused by a different virus than Covid-19.

One advantage ivermectin has over other potential Covid-19 treatments is that it has already been approved by the World Health Organization as an “essential medicine.” The drug was endorsed by US authorities in 1996.

This means there would be fewer regulatory obstacles to getting the drug on the market if human trials prove its effectiveness. Ivermectin is already being produced by a number of international pharmaceutical companies.

Jan said ivermectin was “safe at relatively high doses, widely available, and relatively cheap, too,” but noted tests had only been conducted in the laboratory. Human trials were needed to check safety levels for Covid-19.

“It is important to stress that no-one should try to self-medicate with versions of ivermectin that are for veterinary purposes or head lice,” he said, cautioning that the only safe course was a doctor’s prescription.

Victorian Health Minister Jenny Mikakos agreed, warning that misuse of ivermectin, which is sold as a shampoo, tablet or lotion, could be fatal.

The molecular structure of a coronavirus. Photo: AFP via Getty

“There is no reason to be buying lice treatment unless you’re going to be using it on your children’s hair,” Mikakos said. “I don’t want to see people rushing out to their pharmacies or their supermarkets buying lice treatments now because scientists are doing this work.”

There has already been a sudden surge in demand for the drug, whose side-effects can include dizziness, abdominal pains, vomiting and nausea. In rare cases it can lead to an increased heart rate or low blood pressure.  

Similar warnings have been issued against self-medication with the controversial antimalaria drugs hydroxychloroquine and chloroquine, which Australian authorities have approved for treatment of Covid-19.

Human tests are still being conducted on the effectiveness and safety of the drugs, including a research program at Queensland University, but the Australian government said that therapeutic goods registration rules had been waived so they could be used to treat patients outside the trials.

The US Food and Drug Administration has also fast-tracked the approval process for hydroxychloroquine after it was strongly backed by President Donald Trump, despite concerns that its safety had not been established.

Malaria treatment cloroquine’s efficacy in treating Covid-19 is in doubt. Photo: Facebook

New York state, one of the areas worst-affected by Covid-19, last week began the first large US clinical trials of hydroxychloroquine’s  benefits.

Queensland researchers are studying the efficacy of both drugs, singularly and together.

A French study of hydroxychloroquine found some benefits, but its findings were disputed as some data was omitted. Another trial in China did not record any changes in Covid-19 patients given chloroquine.