The idea that hydroxychloroquine could be used in the treatment of COVID-19 emerged with stories that small groups of patients in China and then France who were given hydroxychloroquine showed signs of recovery, after only six days of therapy, with an astounding 70 percent efficiency.
Since hydroxychloroquine emerged as a potential cure, US president Donald Trump has been rather enthusiastic about the drug, in the process ensuring that almost everyone now knows about it.
Hydroxychloroquine is the main ingredient in drugs normally used to treat malaria and arthritis, and it has been around for a long time.
According to the initial study, the percentage of patients who were given hydroxychloroquine and additionally treated with the antibiotic azithromycin, the treatment was shown to be 100 percent efficient. So, can a drug dating from WWII be effective enough to fight the novel virus, about which we still don’t know enough?
We’ll try to explain the process behind this idea, and see why scientists still haven’t lost hope of fighting this disease — especially when we know that a potential vaccine is still a long way and a lot of clinical testing away.
So, what’s the idea behind using old medications?
Well, because new drugs have to pass a lot of testing, including randomized clinical trials in humans, we can’t just sit back and relax while the pandemic is spreading with terrifying speed. The strategy of using old antiviral drugs as a potential cure lies in the idea that we already know how that drug works, and maybe more importantly – what its side effects and potential interactions with other known medications are.
Hydroxychloroquine — a form of chloroquine with a better clinical safety profile, especially during long-term use — was shown to be effective against the SARS-CoV from 2006, albeit in laboratory conditions. Given the similarity of that virus and the novel SARS-CoV-2, groups of scientists from around the world have tried to use the same drugs in these new conditions.
What is chloroquine, and how does it work?
Chloroquine (or its analogue, hydroxychloroquine) is a drug mainly used to treat and prevent malaria and diseases caused by amoebas. Because it has a mild effect in suppressing the immune system, it can also be used in treating certain autoimmune disorders, such as rheumatoid arthritis and lupus erythematosus. So, what is the mechanism of action of chloroquine in viral diseases?
Cells in our body, among many structures, possess three types of endosomes, vesicles which purpose is to help transportation inside the cell, which basically means that they carry substances in and out of the cell. The pH value found in endosomes is acidic (ranging from 4.5 to 6.5 on the pH scale), which is ideal for many enzymes to work properly.
Viruses are sometimes able to bind and enter the cell by “hijacking” these vesicles, and use their transporting role to transfer near the nucleus of the cell, where the conditions for replication of the virus are perfect.
Hydroxychloroquine, on the other hand, is a weak base, meaning that it is placed higher on a pH scale. Therefore, when hydroxychloroquine enters the cell, and subsequently, endosomes, it increases their pH value, effectively inhibiting the acidification of endosomes.
Other than this, hydroxychloroquine has another role in helping our body cope with the disease, by modifying the immunological answer in the ways of decreasing the inflammation effects activated by the immune system.
What about azithromycin?
Azithromycin, albeit an antibiotic drug from the macrolide family, was also shown to have certain antiviral properties. To be more precise, its mechanism of action can induce expression of interferons, signal proteins released by infected cells, as well as other receptors. These effects were even earlier proven in laboratory conditions when putting it against Zika and Ebola viruses.
Azithromycin, utilizing these anti-inflammatory effects may not do much by itself, but it can reinforce the effects of hydroxychloroquine. The same study has shown that adding azithromycin showed significantly greater efficiency in the elimination of the virus.
So, now what?
Unfortunately, it’s not that easy.
First, the therapy didn’t lead to any kind of response from two patients (who were close relatives), meaning that there are probably limitations to the use of this procedure. We will find that out only after we test enough people who haven’t responded to therapy, and ensure that the therapy didn’t show any exacerbations or complications of existing disease in any other patients.
Keeping all this in mind, a person may ask themselves why don’t people with COVID-19 just start using these medications and heal themselves, especially having in mind that they are relatively cheap?
Still, even if these drugs were to be officially prescribed as a COVID-19 treatment, don't try to cure yourselves with over-the-counter chloroquine, You can not predict the possible side effects, effectively making things worse, and your condition unstable. Instead, try to be patient and smart, while listening to experts — and leave the treatment part to your doctor.
An August 2020 update: Where is hydroxychloroquine now?
Since the possibility that hydroxychloroquine could be used in the treatment of COVID-19 first emerged, scientists around the world rushed to evaluate the efficacy and safety of this medication for coronavirus patients. Despite the hype, the drug has not lived up to many people's expectations.
As of June 2020, the World Health Organization halted further research into the use of hydroxychloroquine as a treatment for hospitalized COVID patients, as the drug was not found to reduce the risk of death among these patients.
In the United States, the FDA is now cautioning against the use of hydroxychloroquine and chloroquine in patients in hospital with COVID-19, outside of clinical trials. Not only is there simply not enough evidence that these medications can lower the risk of death or speed up recovery in COVID patients, hydroxychloroquine was further found to have serious side effects. Kidney and liver failure, themselves rather dangerous, are among the potential complications.
The moral of the story remains the same — unless you are part of a clinical trial, do not turn to hydroxychloroquine as a COVID drug. The potential prophylactic effects of hydroxychloroquine are still being researched, but do not experiment on yourself by attempting to buy it either.