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Could chloroquine treat coronavirus? Five questions answered about a promising, problematic and unproven use for an antimalarial drug

A package of chloroquine phosphate tablets
A package of chloroquine phosphate tablets.

This article is republished from The Conversation. 

An Arizona man died, and his wife was hospitalized, after taking a form of chloroquine, which President Trump has touted as an effective treatment for COVID-19. The couple decided to self-medicate with chloroquine phosphate, which they had on hand to kill parasites in their fish, after hearing the president describe chloroquine as a “game changer.”

Dr. Anthony Fauci, head of NIH’s National Institute for Allergies and Infectious Diseases, quickly corrected the statement, explaining that Trump’s comments were based on anecdotes and not a controlled clinical trial.

Donald Trump’s Twitter feed.@realDonaldTrump

I am a medicinal chemist who specializes in discovery and development of antiviral drugs, and I have been actively working on coronaviruses for seven years.

However, because I am a scientist and I deal in facts and evidence-based medicine, I am concerned about the sweeping statements the president has been making regarding the use of chloroquine or the closely related hydroxychloroquine, both antimalarial drugs, as cures for COVID-19. So let’s examine the facts.

What are chloroquine and hydroxychloroquine?

These are both FDA-approved antimalarial drugs that have been in use for many years. Chloroquine was originally developed in 1934 at the pharmaceutical company Bayer and used in World War II to prevent malaria.

Although the FDA has not approved its use for these conditions, both chloroquine and hydroxychloroquine are also used to treat rheumatoid arthritis and lupus.

What triggered talk that this drug might work?

After the initial outbreak of MERS in 2012, scientists conducted random screens of thousands of approved drugs to identify one that might block MERS infection. Several drugs, including chloroquine, showed the ability to block coronaviruses from infecting cells in vitro. But these drugs were not extensively pursued because ultimately they did not show enough activity to be considered further.

When the new coronavirus appeared, many drugs that had shown some initial promise against the related coronaviruses MERS and SARS were at the top of the list as worthy of further evaluation as possible treatments.

So the science is real, and a number of labs around the world are now investigating these drugs and testing them in clinical trials in the U.S., France and China. But so far, there is no consensus about whether the drugs are safe and effective for treating COVID-19, as it is still very early in the testing process.

Why would antimalarial drugs work on a virus?

It is still unclear how the chloroquines (or any antimalarial drug) would work against COVID-19, which is a virus. Malaria is caused by Plasmodium parasites that are spread by mosquitoes, whereas COVID-19 is caused by the SARS-CoV-2 virus.

Viral infections and parasitic infections are very different, and so scientists wouldn’t expect what works for one to work for the other. It has been suggested that the chloroquines can change the acidity at the surface of the cell, thereby preventing the virus from infecting it.

It’s also possible chloroquines help activate the immune response. One study that was just published tested hydroxychloroquine in combination with an antibacterial drug (azithromycin), which worked better to stop the spread of the infection than hydroxychloroquine alone. However it’s only one preliminary study that was done on a limited test group.

Do other drugs show promise?

To my knowledge, no other antimalarial drugs have shown any meaningful activity against treating coronaviruses. However, another potential drug has risen to the forefront. Remdesivir, developed by Gilead Pharmaceuticals, seems to be highly effective at preventing viruses – including coronaviruses such as SARS and MERS, and filoviruses such as Ebola – from replicating.

In late February the National Institute for Allergy and Infectious Diseases launched a clinical trial for Remdesivir. And this month Gilead launched two phase III trials of the drug in medical centers in Asia.

Should I start taking them to ward off coronavirus?

Absolutely not. Chloroquine and hydroxychloroquine have not been appropriately evaluated in controlled studies, not to mention that they have numerous and, in some cases, very deadly side effects.

No one should take a drug that has not been proven to be safe and effective for a disease or condition for which it is not approved. There are just so many issues that can arise, from side effects to serious toxicity and death due to possible interactions with other medications and other underlying health conditions.

So until these or any drugs have been shown to be effective against SARS-CoV-2 in clinical trials and have been approved by the FDA, no one should be self-medicating.

Katherine Seley-Radtke is a professor of chemistry and biochemistry and president-elect of the International Society for Antiviral Research, University of Maryland, Baltimore County.

Comments (39)

  1. Submitted by Bob Barnes on 03/27/2020 - 09:03 pm.

    Medcram has a detailed explanation of how Chloroquine works with Zinc to stop the virus. The Chloroquine is used as an ion transport to get Zinc into the cell to stop the replication of the virus.

    The fact 2 people were dumb and took fish tank cleaner shouldn’t matter and shouldn’t be any basis for not allowing people to try it if they have nothing to lose. There are quite a few anecdotal stories in the US already of people recovering quickly after getting Chloroquine.

    Not everything needs to be done in clinical trials or double blind studies. The doctors on the front lines are finding this drug to be very effective so the “experts” should be listening to what these doctors are telling them. Also, the CDC knew about Chloroquine working as an anti viral type drug back in 2005.. and said nothing about it during this virus nor did they do anything to further test it over the last 15 years. There will be plenty of time to test these things but if the doctors are finding it works, then they need to be allowed to use it and be listened to.

    • Submitted by George Kimball on 03/28/2020 - 08:04 am.

      Yes, some doctors in multiple countries have found chlorChloroquine to be effective, but there’s a huge asterisk needed with the claim. Their use has been in combination with other drugs (“cocktail”) and typically given at a relatively early onset. So, yes, have at it at your own risk but for god’s sake, let the medical experts talk about it at the White House conference, not our confused and lying president. When he speaks, people die. Let the experts detail how the drug has performed, including exactly how it has been administered, and give the appropriate warnings including zero legitimate studies to date, and let people then make an informed choice.

    • Submitted by David LaPorte on 03/29/2020 - 06:34 am.

      “There are quite a few anecdotal stories in the US already of people recovering quickly after getting Chloroquine.”

      Most people who are infected by coronavirus recover as a result of the action of their own immune systems without taking any drugs. Unless there was a randomly-assigned control group that got a placebo (an inert compound that looks like the drug, but contains no active compounds), there’s no way to know if the Chloroquine played any role in their recovery. And it’s important that neither the patient nor the doctor know who’s getting the drug and who’s getting the placebo to avoid confirmation bias.

      As the author points out, there can be serious side effects from chloroquine and hydroxychloroquine. They shouldn’t be taken unless they’re proven to be effective.

    • Submitted by Pat Terry on 03/30/2020 - 11:32 am.

      It actually really does need to be done in clinical trials. Anecdotal evidence is pretty much worthless.

    • Submitted by Pat Berg since 2011 on 03/31/2020 - 12:20 pm.

      I have one word to offer – Thalidomide.

    • Submitted by Dennis Wagner on 04/02/2020 - 08:31 pm.

      “shouldn’t matter and shouldn’t be any basis for not allowing people to try it if they have nothing to lose” Other than their life? Ah what else is left?
      So your argument is to get rid of the FDA because we have anecdotal evidence and Trumps approval? .

  2. Submitted by Curt Carlson on 03/28/2020 - 09:30 am.

    Off-label use of this unproven, untested (for coronavirus) drug without any scientific basis is making it difficult to obtain for people suffering from conditions for which it has been proven useful, namely lupus and rheumatoid arthritis. There is no rational, humane justification for doing so.

  3. Submitted by joe smith on 03/28/2020 - 10:44 am.

    The couple in Arizona drank aquarium cleaner not a prescribed dose of chloroquine. Please note, no one said drinking fish water cleaner was a way to fight the virus. Chloroquine, along with a Z-pack, seems to have helped many folks with Coronavirus. That is interesting to me since Chloroquine was originally used to help with malaria, a parasite illness. Not making chloroquine available to folks with the illness is just plain stupid. Never thought I would see the day where a media narrative would drive medical practice.

    • Submitted by Pat Terry on 03/30/2020 - 11:35 am.

      Actually, what is stupid is telling people to take an unproven drug, especially now that people with conditions that it does work for are having trouble getting it.

      But this is what happens when you elect a game show host who blew his huge inheritance and failed in nearly every business venture he tried.

    • Submitted by Edward Blaise on 03/30/2020 - 02:43 pm.

      “Never thought I would see the day where a media narrative would drive medical practice.”

      I could not agree more with you:

      “Gregory Rigano has been everywhere lately. The night before President Donald Trump promoted a potential treatment for the coronavirus, the anti-malarial drug chloroquine, Rigano was on Tucker Carlson’s prime-time Fox News show heralding the supposed breakthrough involving the drug: “What we’re here to announce is the second cure to a virus of all time.” He was identified as an adviser to Stanford University School of Medicine. Rigano also appeared on Glenn Beck’s radio program this week, and Tesla founder Elon Musk tweeted out Rigano’s self-published paper about the effects of chloroquine.

      But Rigano is not a doctor. Nor is he affiliated with Stanford’s medical school — it is actively trying to get him to stop saying he is an adviser. And his claims about chloroquine are unproven, often overstated and potentially harmful.

      Rigano and his associate James Todaro have rapidly gained attention for their paper on chloroquine, self-published on Google Docs, which they claim to have written “in consultation with Stanford University School of Medicine, UAB School of Medicine and National Academy of Sciences researchers.”

      Stanford University School of Medicine and the University of Alabama, Birmingham, School of Medicine told HuffPost that no one from their institutions was directly involved in Rigano and Todaro’s paper. The National Academy of Sciences was also not aware of any connection between Rigano or Todaro and the organization, according to a spokesperson. One UAB researcher requested that his name be removed from the paper after he was initially listed as an author and denied he had any knowledge of it or any part in its creation, he told Wired magazine in a Thursday profile of Rigano and Todaro.

      Both Stanford Medicine and its SPARK Program in Translational Research, a drug development partnership with industry, also explicitly told HuffPost that Rigano is making a false claim about his affiliation with the university and have contacted LinkedIn to demand the company remove the university from his profile.”

  4. Submitted by Robert Ahles on 03/28/2020 - 11:23 am.

    Coronavirus Health Advice – James Robb, MD FCAP

    4) Stock up now with zinc lozenges. These lozenges have been proven to be effective in blocking coronavirus (and most other viruses) from multiplying in your throat and nasopharynx. Use as directed several times each day when you begin to feel ANY “cold-like” symptoms beginning. It is best to lie down and let the lozenge dissolve in the back of your throat and nasopharynx. Cold-Eeze lozenges is one brand available, but there are other brands available.

    • Submitted by Paul Udstrand on 04/01/2020 - 09:43 am.

      There is no conclusive evidence that Zinc lozenges kill corona virus, let alone THIS corona virus. Clinical trials have been mixed. By and large zinc won’t harm most people but it can cause some GI problems for some people.

      The real danger with this alleged “treatments” is that people who use them will decide they’re not contagious or that they can ignore social distancing, hand washing, and other precautions because they’ve got a “cure” in their pocket. Then they out and kill people with their un-contained un-treated viral loads.

    • Submitted by RB Holbrook on 04/02/2020 - 11:22 am.

      Leaving aside questions about the reliability of anything one might read on Patriots’ Soapbox, the linked article has some good advice and some complete codswallop. COVID-19 will not be “be killed by a temperature of just 26/27 degrees [Celsius, I presume].” If it were true, there would be no cases in places like Singapore.

      As far as the rest of the article, consider the source.

  5. Submitted by Joel Stegner on 03/28/2020 - 07:28 pm.

    Trump endorsed this with no evidence No reputable virus research has recomended it. Trump want a cure so he can claim credit for it. He has expressed no public regrets about the death, as that would be admitting a tragic mistake. There is no sign he cares how many die if it is to his benefit.

    Please do not waste our times with Trump’s dangerous notions.His ideas should be disregarded

    • Submitted by joe smith on 03/29/2020 - 08:36 am.

      Joel, totally false, studies are showing chloroquine plus Z-pac to be effective against Coronavirus. A resent study showed 97.5% of patients with the virus responded positively after only a day or two. Chloroquine has been around for 70 years and used as a malaria fighting drug, so it has been thoroughly tested.

      • Submitted by Brian Nelson on 03/29/2020 - 05:59 pm.

        Controlled studies are showing this? Can you please include a link to these studies?

        • Submitted by joe smith on 03/30/2020 - 10:20 am.

          No controlled studies yet, this crisis just started. There are many controlled studies on chloroquine and its effects on the human body, drug has been approved and around for 70 years. All the studies are antidotal, coming from Doctors who have treated patients. If the drug cannot hurt you and has been shown to help with Coronavirus here and Europe why in the world would you not try it.
          This is the same argument folks against Trump’s bill “right to try” use. To get a study done or a drug to market takes years, (thanks to red tape by 4-5 huge Govt agencies). I will take antidotal evidence by Doctors saying they have had success with a known substance (chloroquine) any day of the week.

      • Submitted by Pat Terry on 03/30/2020 - 11:36 am.

        Studies? What studies?


  6. Submitted by joe smith on 03/30/2020 - 10:29 am.

    BTW, the FDA just approved chloroquine, from antidotal evidence, to fight Coronavirus. Thank goodness there are proactive, thinking out of box folks in charge of this epidemic. Normal scared to make a decision career politicians would be screaming “where is my study”!

    • Submitted by Paul Udstrand on 04/01/2020 - 09:45 am.

      Dude, this is standard practice for a science based government agency. As the author here points out, the science behind this decision dates back over a decade. This is comparable to private sector “inovation” of any kind.

    • Submitted by RB Holbrook on 04/01/2020 - 02:25 pm.

      “Normal scared to make a decision career politicians would be screaming “where is my study”!”

      Normal, career employees at the FDA are not “politicians,” according to the Hatch Act. Believe it or not, some people still care about ethics in government.

      Normal, career employees at the FDA supposed to be protected by federal law, so that when they go against the ill-informed opinions of an uneducated doofus they don’t have to worry.

      Normal, career employees at the FDA are also trained in biological sciences, medicine, and pharmacology, so they know how valueless anecdotal evidence is.

      Normal, career FDA employees are more concerned with scientific and medical efficacy than they are with TV ratings.

      Normal, career FDA employees know that anecdotal evidence is tainted by things like self-selection bias (are the failures reported?) and by the placebo effect.

  7. Submitted by Dennis Tester on 03/30/2020 - 02:52 pm.

    As of today, 1100 patients in New York are being given the chloroquine/Z-pac cocktail. We should know in a few days whether or not it works. Trump’s instincts are right again.

    • Submitted by Brian Nelson on 03/30/2020 - 03:39 pm.

      I hope he is right. But, as far as his instincts:

      “[W]hen you have 15 people, and the 15 within a couple of days is going to be down to close to zero, that’s a pretty good job we’ve done.” DJT, 2/26/20

    • Submitted by Edward Blaise on 03/31/2020 - 08:13 am.

      “We should know in a few days whether or not it works. Trump’s instincts are right again.”

      And there you have the essence of Trumpism: One has no idea if something works or doesn’t, is right or wrong; but declare victory anyway and move on to the next fake scenario.

      As Kelly Ann challenged us weeks ago:

      “It’s contained”

      “Do you think it’s not contained?”

    • Submitted by Paul Udstrand on 04/01/2020 - 09:30 am.

      Dude, don’t quit your day job. You’re obviously not a medical professional. What makes you think anyone in NY can complete a drug trial in a few days?

  8. Submitted by Henry Johnson on 03/30/2020 - 06:00 pm.

    My belief is that 98% of the time, Donald Trump has been much more unfair to the media than the media has unfair to him.

    This started at the very first press conference where the media was unfairly blasted by Sean Spicer for not passively accepting the lie that the inauguration crowds for DJT were larger than those for Obama.

    That war on the media has continued unabated, and today he was lashing out a reporter for being unfair to him when they asked about his statements that he was going to offer federal assistance to governors based on how “appreciative” they were.

    And he responded immediately by saying – “I never said that” – which is a lie because he did – in public!

    And then he launched into an unfair attack on the reporter, for not accepting the lie, and not going along with it.

    There are exceptions to the rule however of DJT being more unfair to the media instead of the other way around though, and the president’s advocacy of Chloroquine, and the coverage of that advocacy, I do think has been somewhat unfairly covered and treated by the media.

    Yes, DJT should have been more cautious and expressed how we as a society can’t afford to pin our hopes on this drug as a cure or even something that might moderate the symptoms of the disease and lower mortality rates – it does need more testing and we can’t abandon the things we know do help, while hoping for treatments or vaccines.

    However, the media hasn’t done it’s research in that unlike claims I’ve heard for example from Sanjay Gupta, that the president’s advocacy is based solely on one French study with only 20 or 25 patients, the drug in fact has been used in several other countries, and is in fact one of the recommended drugs in China in it’s treatment guidelines.

    Note this press release from China where they advocate the use of Chloroquine, and note it indicates how clinical trials are underway in 10 Chinese hospitals at the present time –

    They have also added it to their formal treatment protocol for covid-19 –
    Please see section 10, ‘Treatment’, and then the 4th paragraph of part B, which discusses using Chloroquine phosphate..

    While it’s true the drug lacks double-blind studies with large numbers of patients, the article below talks about how a number of countries – France, China, Korea and Italy, have found some promising results using the drug, and a number of researchers are fairly excited about exploring it further.

    So I think it was somewhat unfair, and also inaccurate, to bash the president as much as the press has, for his having watched Fox news and hearing stories about this promising new drug and then pitching it as a possible solution.

    Yes, it may or may not turn out to be as useful as the Chinese and some researchers are saying, but as long as it’s tempered in the president’s remarks with the FACT that for now testing and social isolation and getting our hospitals the equipment they need are our proven paths out of this mess – expressing some hope for a drug that we already know the risk profile for, and is inexpensive (about 10 cents a pill), IS in my opinion something good, not something to be criticized about in such a one-sided way.

    And I agree with the fact that some idiot without dosage guidance consumed a non-pharma grade fish medication should not be blamed on the president and has no bearing on the value or lack of value regarding the drug.

    It’s been on the market for over 50 years for routine use as an anti-malaria treatment and preventative, so it’s risk profile is well known.

    BTW, the main risk for Chloroquine as I understand it, is that it can tend to cause arrhythmia (the heart beating in an irregular rhythm).

    So someone who already had arrhythmia would probably only want to take the drug under the monitoring and advice of their MD.

    The Z-pack antibiotic also tends to bias people somewhat towards arrhythmia, so there’s a double risk in the cocktail the French researchers were excited about in their small study.

    However, many people without heart issues could use the cocktail I believe, and even those with some heart problems could perhaps use it under the guidance and monitoring of their doctor.

    There is a risk of course associated with many, many drugs, that doesn’t mean that they aren’t valuable if used with discretion.

    At the U of M right now they are recruiting for a study which will see if taking the drug by those who are taking care of someone who has an active case, or who have been exposed to someone with an active case has any preventative effect for those taking Chloroquine.

    And other studies are underway to evaluate it as a treatment for those actively infected with covid-19.

    We’ll have to see what those studies show, but for now, gearing our testing up to a mass scale (as they did in Korea), getting needed medical supplies and equipment to medical staff, and social isolation are the only things we can count on.

    But IMO, the press should cool it a bit with criticizing the president for his advocacy of Chloroquine – IMO this is one case where there’s been kind of one-sided, knee-jerk take on the situation on the part of the media, that’s been a little overdone.

    • Submitted by Dennis Wagner on 04/02/2020 - 08:48 pm.

      OK Henry, good case, however, got a guy that lies 70% of the time, and exaggerates the other 30%, has told the world many times science is fake, so where is my reason to believe anything he says? Now, he also has Dr. Fauci, (deep state science, 3 terrible words to republicans) within a sociable distance, if there was credence to this, why didn’t/wouldn’t Fauci endorse it, or provide some dialogue? You now have a trained audience that will either believe 100% un-questioned or not beleive 1% with all the questions, he did it to himself, no other excuses.

  9. Submitted by Edward Blaise on 03/31/2020 - 02:57 pm.

    As Aesop told us in the fable of “The Boy Who Cried Wolf”:

    “The moral stated at the end of the Greek version is, “this shows how liars are rewarded: even if they tell the truth, no one believes them”. “

  10. Submitted by Ron Quido on 03/31/2020 - 05:00 pm.

    Just think of what would happen in COVID-19 were spread by mosquitos!

    • Submitted by Paul Udstrand on 04/01/2020 - 09:55 am.

      It would be lot easier to contain if were a vector borne disease. When was the last time you heard about a Yellow Fever outbreak?

  11. Submitted by Paul Udstrand on 04/01/2020 - 09:28 am.

    I’m sure I don’t need say this but just in case: DO NOT take medical advice from anyone on a comment thread like this.

    This is one scenario where anecdotes pretending to be legitimate research and discovery can get people killed. Ineffective treatments “discovered” on the web may or may not be directly harmful or toxic, but that doesn’t mean they’re harmless. Anything that might be strong enough to attack this virus might well be strong enough to do some damage. It’s not just about the compound, it’s also about dosage and side effects.

    For instance, with a drug like Chloroquine it’s possible that normal dose used to treat Malaria is not sufficient to treat COVID 19. Higher doses of Chloroquine can cause psychosis, I’ve actually see this once working on a psych unit. We had a patient who came in psychotic because her pharmacy accidentally dispensed Chloroquine instead of Quinidine.

    So even if something like Chloroquine is found to be an effective antiviral in the lab, it might not be possible to modulate the dosage to treat COVID 19 safely. Safe treatment regimes can only be determined scientifically, no Doc somewhere in the webiverse is going to figure that out on their own, and post it for bloggers to disseminate.

  12. Submitted by Paul Udstrand on 04/01/2020 - 09:53 am.

    Just to repeat part of an earlier comment: The real danger with these alleged “treatments” is that people who use them will decide they’re not contagious or that they can ignore social distancing, hand washing, and other precautions because they’ve got a “cure” in their pocket. Then they go out and kill people with their un-contained un-treated viral loads.

    As of this moment, there is NO known effective treatment beyond basic supportive medicine that treats symptoms of COVID 19. Your best bet is to try to avoid infection in the first place, and isolate for 14 days and hope you don’t need treatment if you DO get COVID 19.

  13. Submitted by Edward Blaise on 04/01/2020 - 10:58 pm.

    The COVID19 disaster is in many ways is a time compressed Climate Change scenario.

    It is clear in the virus scenario to see that politicians overruling scientific research and guidance because it did not fit their narrative of choice has VERY BAD consequences.

    COVID19 got to that conclusion in weeks. Climate change is the same thing except days become years and when the reckoning facts finally become absolutely clear, climate change deniers will be like their virus minimizing comrades: “it will just disappear in a few weeks” becomes “we’ll lose thousands, nobody could have foreseen this”…

    • Submitted by Paul Udstrand on 04/02/2020 - 09:22 am.

      Edward, I’ve been thinking almost the exact same thing.

      It’s been kind of amusing and interesting to watch the usual suspects flail around with their attempts to debate game the pandemic. This crises is moving so quickly and is so immediate and deadly that there just isn’t space for “alternative” facts or sophomoric rhetorical games.

      You can’t game a pandemic, and you can’t sell a virus as a political debate. Attempts to play the pandemic like they played climate change, and anything else simply collapse under the weight of information within days if not hours. If people weren’t dying it would be comical.

      It’s interesting to see anti/small guvment Libertarians and Republicans flail around trying to apply their circular mentality to this crises. They cannot escape their own logic which dictates that government must be responsible for all evils… how do to you maintain THAT mentality when YOUR guys are in charge of the government? The impulse to blame government interference clashes with the impulse to celebrate Trump’s government. Trump’s impulse to keep government out of the way clashes with climbing infection and death rates, and supply shortages and testing failures. Debate game attempts to brag about how many tests have been done simply crash when someone asks an obvious question about the per-capita rate and so it goes. You can’t claim that anyone who wants a test is getting a test when almost everyone who’s supposed to do the tests is reporting shortages.

      Seriously, these guys are looking at Trump’s TV ratings as if that’s a measure of effective leadership? If nothing else this pandemic has seriously drawn the disconnected nature of the Republican relationship with reality out into the harsh light of day.

  14. Submitted by Dennis Wagner on 04/03/2020 - 11:52 am.

    Just in: Fake Treatment?

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