• A variant of remdesivir, one of the most promising treatments for COVID-19, has for more than a year been sold as a treatment for sick cats via a black market connected to big Facebook groups.
  • The drug, called GS-441524, is being sold as a purported cure for Feline Infectious Peritonitis, which is caused by a coronavirus, the same family of pathogen that causes COVID-19 in humans. 
  • Despite not being licensed as a treatment for FIP by the Food and Drugs Administration, the drug is being sold to US consumers by Chinese firms, with courses sold for up to $10,000.
  • The transactions do not take place on Facebook’s platform, but large cat owner groups have banded together to connect buyers to sellers, and attempt to screen the drug for purity.
  • An academic who pioneered using the drug on cats says that a black market is the only option because pharma giant Gilead, which has the rights to GS, will not license it for use in cats.
  • Critics say the unlicensed trade can lead to dangerous, low-quality drugs which could even find their way into human use.
  • Visit Business Insider’s homepage for more stories.

As the world seeks a way out the coronavirus crisis, there are hopes that the drug remdesivir may provide part of the solution.

The drug is already being used on seriously ill patients after being fast-tracked by medical authorities in the US, though supplies are limited and it may be some time before it becomes more widely available. 

Business Insider can reveal that a black-market version of the drug, known as GS, is already being used by pet owners to treat a rare but deadly disease suffered by cats.

Unlicensed doses of GS — solid in liquid form and distributed in vials — are available through an extensive network of online vendors in China created to serve worried pet owners.

Remdesivir2 by Getty Images

Vials of the drug remdesivir as seen at University Hospital Eppendorf in Hamburg, northern Germany on April 8, 2020.

ULRICH PERREY/POOL/AFP via Getty Images


Thousands of owners with sick cats have banded together in closed Facebook groups, which connect buyers and sellers, and make efforts to screen shipments for purity.

Though no money is exchanged via Facebook, the network acts as a conduit through which people can access the unlicensed drug. 

A Facebook spokesperson directed Business Insider to the site’s policies, which ban the sale of illegal or prescription drugs on the platform, and encourage users to report drug sales. It also said it is using automated technology to scan and identify instances.  

Business Insider has seen price lists from vendors of the drug suggesting that it is being sold for as much as $10,000 a course, and sent to the US under the guise of a dietary supplement.

Some people have also tried to buy it as a backstreet coronavirus remedy for human use, but it is not clear how widespread this is.

The cat disease in question is Feline Infectious Peritonitis (FIP). Cats with FIP suffer fever, weight loss and breathing difficulties, and nearly always die.

It’s caused by a type of a coronavirus — the same family of pathogen that causes COVID-19 in humans. Though they are genetically related, the FIP coronavirus does not cause COVID-19, and vice-versa.

The drug being used to treat it is GS-441524, or GS for short. It is being marketed and sold by companies based in China, which ship it to the US.

Emeritus Professor Niels Pedersen, a veterinary science expert at University of California Davis, says he personally pioneered its use on cats.

Pedersen reluctantly supports cat owners seeking to administer the drug to their pets, since there is no legal way to acquire the drug. He told Business Insider that FIP is “now 80% or more curable” with GS.

Professor Margaret Hosie, an FIP researcher at the University of Glasgow, told Business Insider that she too had heard anecdotal reports of GS being effective. The closed Facebook groups are also full of stories of GS working.

But the Food and Drugs Administration told Business Insider it has not licensed GS-441524 as a treatment for FIP, which means it is illegal to sell it as such in the US.

Some sites market it instead as a human dietary supplement, Pedersen said, which allows it to be shipped to the US.

One campaigner, Anna Mitchell, who has spent a year investigating the GS black market, has called for it to be closed down. 

Mitchell started to investigate after her own cat got FIP, she told Business Insider.

“However the injections, the web of lies [about the effectiveness of the drug] and the misinformation is rampant,” she said.

“And I am also worried that pretty soon the model we are seeing develop could spread to [unlicensed treatments for] other feline diseases and also human diseases.”

Oksana Pyzik, a senior teaching fellow in the School of Pharmacy at University College London, is an expert on the illegal pharmaceuticals market. She told Business Insider that the batches of GS being produced in China could be dangerous.

“Any medicine that has not been properly investigated for its quality means that we don’t know what is inside, whether it is contaminated, whether it has any of the active pharmaceutical ingredients it claims to have,” she said.

In Facebook groups, desperate pet owners speak of a “miracle cure” 

Cat2 by Getty Images

Feline Infectious Peritonitis is a rare disease suffered by cats — and an online black market has emerged around a potential cure

Getty Images


Facebook groups with thousands of members have have developed in response to the spread of FIP. 

In the groups, members exchange support and advice on how to treat cats with the disease — and stories of what they claim are the amazing curative powers of GS.

Members speak often of a promising February 2019 field study by Pedersen, the UC Davis professor.

A field study is a collection of information outside a lab setting. In Pedersen’s study he dosed 31 cats suffering FIP with GS. 25 survived and recovered. 

Robin Kintz, who started the 23,000-member group FIP Warriors, told Business Insider: “When my kitten Henry was diagnosed in February of 2019, I searched the internet for answers and solutions.

“I came across Dr. Pedersen’s research using GS-441525 and then went onto Facebook searching for sources of this miracle drug.”

GS-441525 was used in clinical trials on humans while the Ebola outbreak was raging in 2012. However, the trials failed.

After this, Pedersen began experimenting to see if GS could work on animals, he told Business Insider. 

In an email, he said that GS and remdesivir are very similar, a conclusion backed by other researchers.

Pedersen said that he asked permission to legally make GS for cats, but was rejected by Gilead, the pharmaceuticals firm that owns the rights to it.

Pedersen claims that Gilead is worried that allowing GS to be used on cats would harm its ability to profit from its use in humans. The company did not respond to several requests to comment.

Pedersen said that desperate pet owners have been driven to the black market as a result.

He is convinced the drug works, and claims that 10,000 cats worldwide have been treated for FIP using GS thanks to his research.

“This disease, which is virtually always fatal and accounts for 0.3-1.3% of all deaths of cats in the world, is now 80% or more curable with GS-441524,” he said.

Pedersen also referred to an earlier statement where he defended helping the black market groups.

He wrote: “I will continue to provide as much advice as possible for owners and veterinarians using and contemplating the use of black-market GS and GC to treat cats with FIP.”

He told Business Insider that his veterinary oath compelled him to help pet owners administer the treatment. 

The statement continued: “I must make it clear that I would have preferred these drugs to be approved and commercialized in the normal manner. I am certain that this will happen within the next few years, and as it does, the black market demand for drugs like GS and GC will wane.”

Sold online for as much as $10,000 

But Mitchell, the anti-black market campaigner, says that the support Pedersen has offered to individuals administering illegal GS has encouraged a potentially dangerous black market. 

“It ballooned in Facebook groups — specifically one that has become gigantic and is really the supply route between the manufacturers and their buyers in the US,” she said.

The cost of a course of treatment can come to about $10,000. The screenshot below shows the price for a course of 29 bottles, which Mitchell told Business Insider is the amount an owner might want to obtain to treat a serious FIP case.

In messages posted inside a Facebook FIP group, cat owners spoke of similar prices.

cat drug screenshot border

A price calculator from a firm selling black-market GS shows the cost a 29-bottle course.

via Anna Mitchell


Mitchell said: “I am surprised by how many people, even those without the money, find a way to acquire that drug, they will go into debt, they will do anything to save their cat. It is a huge, huge market.”

She said some owners report worrying side effects in their pets, including open sores and wounds from the injections. Other cats are said to relapse after seeing symptoms briefly improve. 

Kintz, the group administrator, said that some pets experience negative side-effects, but that the group makes efforts to screen batches for purity.

“Lesions and painful injections are the two most common side effects of the medication. Some sores are worse than others but all resolve with time,” said Kintz.

“Early on when this group was formed, we were able to have several different ‘brands’ of GS vials tested in a reputable university lab and the results confirmed the biological activity of the GS,” she said.

Kintz also said the group asks for free batches from suppliers to give to owners who cannot afford the drug.

“They use the vials as a mini field trial. If the kitties get better, we know it is working.”

Humans who believe GS might be a coronavirus treatment seek it out in Facebook cat groups

Recent clinical trials for remdesivir as a treatment for COVID-19 have been so encouraging that Gilead recently signed an agreement with several firms in India and Pakistan to increase production of the drug. 

However, a form of the drug is still not expected to be widely available on the legitimate market for many months.

Pyzik, the pharmaceuticals expert, expressed concern that people pursuing a treatment for COVID-19 could seek out unlicensed forms on the black market. 

“It is incredibly serious to take a medicine when we don’t understand the full nature of its effects in someone that has a coronavirus infection.

“Again, premature use can lead to a whole series of very serious side effects that can have long lasting disabilities for a person in the future,” she said. 

Kintz said that some had inquired through her group about getting GS to treat COVID-19. 

“One or two people have reached [out] wanting to get GS for the human coronavirus but  we have not gotten involved with that at all,” she wrote.

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