So doctors are looking to drugs that are already approved for treating other diseases. But medicines developed for those ailments are showing some promise against the respiratory illness at the center of the pandemic. This drug has been used to treat patients with malaria for nearly a century. It is a synthetic version of quinine , a natural compound that people have been extracting from the bark of cinchona trees since the early s.
Chloroquine works by essentially slowing down how efficient the virus is at entering cells, which can slow the rate of replication, said Karla Satchell , a microbiologist at Northwestern University Feinberg School of Medicine. To fight malaria, it essentially helps poison the digestive system of some blood parasites in the genus Plasmodium that are spread to humans through infected mosquitoes.
Sign up for the latest news, best stories and what they mean for you, plus answers to your questions. COVID is caused by a coronavirus, not a parasite. Chloroquine has several built-in advantages. As you may guess, this drug is closely related to chloroquine. Scientists think it works by disrupting communications between cells in the immune system. Like chloroquine, scientists suspect it might help to mitigate cytokine storms.
Doctors are testing it in COVID patients on the theory that if chloroquine is helpful, hydroxychloroquine might be too, and recent lab results seem to back that up. At least seven clinical trials have begun in China to test hydroxychloroquine in patients with COVID, and the University of Minnesota also launched one of its own this week. On Saturday, he tweeted out an endorsement of a preliminary report from France in which six patients received hydroxychloroquine along with the antibiotic azithromycin.
This combination of two antiviral drugs, lopinavir and ritonavir , is used to combat HIV. The two drugs, both protease inhibitors , have different but complementary roles when used in combination. This drug was developed by Gilead Sciences to fight Ebola but failed to prove effective.
Still, remdesivir has since been shown to have some effect against both MERS and SARS in cell lines and limited animal testing, and since those diseases are caused by coronaviruses, it may have some effect against the one that causes COVID Exactly how remdesivir works has been unclear, though a new study shows that it appears to block RNA replication during the reproductive cycle of a coronavirus. It was given to the first COVID patient in the United States for compassionate use after his condition took a turn for the worse, and he began to recover the next day, according to a case study published in the New England Journal of Medicine.
Whether the drug was actually responsible for any of that improvement is unknown.
New study casts doubt on hyrdoxychloroquine's effectiveness in treating coronavirus
Several clinical trials in the works should provide some answers. A clinical trial sponsored by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, has already launched at several locations in the U. Anthony S. This hypertension drug reduces blood pressure by preventing a hormone called angiotensin from binding to receptors on blood vessels, allowing them to stay relaxed.
Scientists hypothesized that losartan might help patients with COVID because, as an angiotensin receptor blocker, it obstructs the site through which the virus gets into the cells, Tolar said.
This drug rounds out the trifecta of treatments that University of Minnesota researchers are putting through clinical trials ; they have not yet started recruiting subjects, according to the NIH. The trick is to figure out where to stick the screwdriver, and what it should look like.
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The advantage here is that you get a drug that does essentially exactly what you want it to do. The drawback is that scientists have to start from the ground up, so getting a drug to the public may take a little longer — perhaps two years, Satchell estimated. New ones are being added every day, as the case count in the U. The drugs being tested range from repurposed flu treatments to failed ebola drugs, to malaria treatments that were first developed decades ago. The antiviral drug, called Favipiravir or Avigan, has been used in Japan to treat influenza, and last month, the drug was approved as an experimental treatment for COVID infections, Pharmaceutical Technology reported.
So far, reports suggest the drug has been tested in individuals in Wuhan and Shenzhen. The drug, which works by preventing certain viruses from replicating, seemed to shorten the duration of the virus as well as improve lung conditions as seen in X-rays in tested patients, though the research has yet to be published in a peer-reviewed science journal.
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Chloroquine and hydroxychloroquine have been approved by the U. Food and Drug Administration for the treatment of malaria, lupus and rheumatoid arthritis, but preliminary research in human and primate cells suggests that the drugs could effectively treat COVID A study found that chloroquine could quell the spread of SARS-CoV when applied to infected human cells in culture.
The cell culture studies of SARS-CoV-2 revealed that the drug and its derivative hydroxychloroquine undermine the novel virus' replication in a similar way. The FDA is organizing a formal clinical trial of the drug. As of Feb. In addition, the University of Minnesota is studying whether taking hydroxychloroquine can protect people living with infected COVID patients from catching the virus themselves.
In one heavily referenced study , conducted in France, a small number of patients with COVID received either hydroxychloroquine alone or hydroxychloroquine in combination with an antibiotic called azithromycin. The authors reported that detectable concentrations of SARS-CoV-2 fell significantly faster in the study participants than coronavirus patients at other French hospitals who did not receive either drug.
In six patients also given azithromycin, this promising effect appeared to be amplified. However, the CDC noted that the small, non-randomized study "did not assess clinical benefit[s]" associated with the treatment; in other words, the study did not probe whether the treated patients were more likely to recover and survive their illness. Additionally, the agency advised that doctors should be cautious when giving either drug to patients with chronic disease, such as kidney failure, and especially those "who are receiving medications that might interact to cause arrhythmias.
The drug was found not to be effective in Ebola, but in lab studies, it has proven effective at inhibiting the growth of similar viruses, severe acute respiratory syndrome SARS and Middle East respiratory syndrome MERS. In a petri dish, remdesivir can prevent human cells from becoming infected with SARS-CoV-2, according to a letter published in the journal Nature in February. The Food and Drug Administration has currently approved use of remdesivir for compassionate use, meaning only patients with severe COVID disease can be approved for treatment.
In other countries, requirements to receive remdesivir may be less stringent.
Coronavirus drugs: Where we are and what we know
Five clinical trials in China and the U. George Thompson, an infectious disease specialist at UC Davis Medical Center who treated an early, severe case of COVID, told Science magazine that their patient got better after getting the drug, about 36 hours after diagnosis. The doctors initially thought the patient would die, Thompson said. However, such anecdotal evidence can't demonstrate effectiveness, and the lab has yet to analyze blood samples to show that the patient's clinical improvement following the administration of remdesivir coincided with a drop in viral load concentration of viral particles.
On the flip side, a study posted to the preprint database medRXiv looked at three patients treated with remdesivir. The study, which was not peer-reviewed, found no clear time-dependent relationship between getting the drug and seeing improvements in symptoms. The patients also experienced rectal bleeding, elevated liver enzymes, vomiting and nausea, which could potentially be tied to the drug. Another quandary is that antiviral drugs generally work better the earlier patients get them, but because remdesivir is not FDA-approved for general use, only patients with the most severe, and late-stage, disease, qualify for its use in clinical trials, Thompson told Science.
On Sunday March 22 , Gilead Sciences announced that they were temporarily halting compassionate use of remdesivir, due to "overwhelming demand. The antiviral drug kaletra, a combination of lopinavir and ritonavir, generated early excitement. However, new data from China, published March 18 in the New England Journal of Medicine , could not detect a benefit when patients took the drug.