WASHINGTON -- Americans and Canadians alike are used to seeing gauzy, pastel-coloured pitches for medicines, therapies and treatments on cable television. They're less accustomed to hearing them delivered live from the White House briefing room.

At times, Donald Trump's nightly news conferences have come to resemble infomercials as the country's pitchman-in-chief promotes hydroxychloroquine -- an anti-malarial drug more commonly prescribed for diseases like lupus and rheumatoid arthritis that the president seems convinced carries promise for COVID-19 patients.

Trump said the U.S. has stockpiled 29 million hydroxychloroquine tablets -- a strategy based on evidence that doctors, health care professionals, governors and infectious-disease experts across the country have described as inconclusive at best and downright dangerous at worst.

On Tuesday, he seized on the story of Karen Whitsett, a state Democrat from Michigan, who told Fox News this week that "she thought she was dead" before trying the drug, which she now credits with saving her life.

"I think she'll be voting for me now, even if she's a Democrat," Trump said. "I don't say that happens with everybody, but that's a beautiful story. There are many of those stories. And I say, 'Try it."'

That's precisely the sort of message Florence Tew doesn't want to hear.

Tew, who lives in Toronto, has been taking the medication for the last 12 years to help manage lupus, which can include debilitating joint pain, rash and kidney problems. She wants nothing more than the world to find an effective COVID-19 treatment, she said -- but not based on unproven theories that come at the expense of her own therapy.

"It's disheartening," said Tew, who described hearing stories online from other lupus patients being warned by their pharmacies that they wouldn't be able to refill their prescriptions -- and in one case, being told by a doctor's office that they would be denied the drug entirely.

"That's when I started to really panic," she said. "You've gotten to a point where you're taking this medication and you just -- you feel good, you're able to work, you're able to function, and then something throws a wrench into it."

Tew said she currently gets a monthly supply of her medication from PocketPills, a B.C.-based pharmacy service that fills, delivers and manages prescriptions online -- and that's beginning to notice warning signs about the drug's availability.

Demand for the drug spiked in North America in the early days of the outbreak, not long after the president began singing its praises, said A.J. Bassi, the company's director of pharmacy services. Oversight bodies like the Ontario Medical Association and the Registered Nurses of Ontario had to issue notices to discourage doctors from stockpiling it.

Since then, although manufacturers insist that the supply of the drug in Canada is currently at typical, pre-pandemic levels, vendors are using historical purchase trends to restrict pharmacies to a 30-day limit on how much they can purchase, he said.

"If I only historically purchased 500 tablets a month, because that's how much I dispense, then that's how much they're restricting that we can purchase," Bassi said. The coming challenge will be dealing with supply-chain problems where wholesalers are forced to use ground transportation to send shipments, leading to potential restocking delays.

"Everybody's going crazy buying toilet paper -- when you need some, you go buy two rather than one, because you're just -- you're afraid. And the same thing in pharmacy -- you're afraid for your patients, so you buy more."

So what's with the president's fixation on hydroxychloroquine?

Conspiracy theories abound, most of them revolving around Big Pharma's long-standing influence in U.S. politics and reputation as a generous campaign donor. The New York Times reported Tuesday that Trump has a small personal stake in Sanofi, a Paris-based drug maker that produces Plaquenil, the brand-name version.

"Hydroxychloroquine can cause serious adverse reactions and should not be taken without medical prescription or advice," the company says on its website. "Sanofi's hydroxychloroquine product is not indicated for use for COVID-19 in any country."

People close to Trump, including billionaire Larry Ellison, television doctor Mehmet Oz and former New York mayor Rudy Giuliani have all been pushing the president to expedite approving the drug for COVID-19, the Times reported. It's also been a popular talking point on Fox News, Trump's preferred cable-news indulgence.

And Peter Navarro, the White House trade adviser, has reportedly been so aggressive in promoting the hydroxychloroquine theory that he got into a Situation Room confrontation on the weekend with Dr. Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases and the face of the government's COVID-19 effort.

Navarro, citing his own research into anecdotal reports of the drug's effectiveness, has parroted the president's thinking.

"History will judge whether this was an efficacious drug," he told CNN. "Right now, in the fog of war, if that can save lives that's a good thing."

The Trump administration's enthusiasm for the drug is based on anecdotal studies conducted on a relative handful of patients, said Dr. Allen Zagoren, a surgeon and professor of public administration at Drake University in Des Moines, Iowa.

"When you have a disease that's affecting a million people, you need to have bigger numbers to project because that could be coincidental -- the disease is very unpredictable," Zagoren said.

"You need to have a big study to predict. When you start throwing stuff at the wall to see what will stick, that's garbled information -- it's garbage in, garbage out."

Then there's the issue of side effects, Zagoren noted: the drug carries a host of potential issues, particularly for people with pre-existing conditions, compromised immune systems, cardiopulmonary problems -- the very people who are most likely to be vulnerable to the severe effects of COVID-19 in the first place.

Hydroxychloroquine is also often administered with an antibacterial known as azithromycin that carries a heightened risk of death in patients with a pre-existing heart condition.

"If I was asked to review a case for a lawyer or the board of medicine that a physician decided to give a drug to the patient that had no proven efficacy off-label and the patient died, that's negligence," Zagoren said.

"Write the cheque, because you can't defend that."

This report by The Canadian Press was first published April 7, 2020.