The story is that small groups of patients in China — and more recently, also France — who were given hydroxychloroquine showed signs of recovery, after only six days of therapy, with an astounding 70 percent efficiency. Hydroxychloroquine is the main ingredient in drugs normally used to treat malaria and arthritis, and it has been around for a long time.
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.