What are Chloroquine and Azithromycin?

There seems to be a lot of confusion over chloroquine and azithromycin, and the nature of antibiotics and antimicrobial agents. Hopefully this article clears up some of the confusion. Multiple citations have been provided so that the reader can do further research. Always consult with a doctor before taking medical action.

The "quine" Family

The grandparent of the "quine" family is quinine. For centuries, people chewed cinchona tree bark to relieve symptoms of malaria. The chemical was isolated from cinchona tree bark in the 1800s and became a common treatment for the disease. In 1934, Hans Adersag discovered chloroquine. While not directly related to quinine, it has a similar chemical structure and functions in a similar way.

These drugs are largely antiparasitics, and malaria itself is generally caused by a number of related protozoan parasite, such as P. falciparum. Sadly, there is some evidence that certain parasites are evolving resistance to these drugs (Zalis et al. 1998).

Azithromycin

"Mycin" itself is a suffix that refers to an antibiotic that is derived from mold. Azithromycin, and its relatives, such as erythromycin, are known as "macrolides" and generally have a specific effect on bacterial protein synthesis (Jelić and Antolović 2016). The drug has been investigated for its efficacy against various forms of Streptococcus infections, as well as B. pertussis, the bacteria that causes Whooping Cough (Peters et al. 1992).

Why the Fuss?

These two drugs have found their way into the news a lot lately, because of their potential to treat cases of SARS-CoV-2 (COVID19 or "the coronavirus"). Many people have snapped at the idea commenting that these drugs are not antivirals. However, many antimicrobial agents have an effect on more than one microbe class.

For instance, in 2004, when it became clear that coronaviruses were not mere nuisances, investigation into chloroquine's efficacy against the original SARS coronavirus was conducted (Keyearts et al. 2004). A year later, another study was published indicating significant ability for chloroquine to inhibit SARS-CoV-1 (Vincent et al. 2005).

As with chloroquine, azithromycin has been identified as having antiviral properties, at least in certain instances. In 2015, the drug was studied for its antiviral properties in cystic fibrosis (Schögler et al. 2015). And a year later, it was investigated for similar antiviral effects in cultured bronchial epithelial cells from COPD patients (Menzel et al. 2016).

It is actually rather frustrating that the amount of research on the topic has not progressed further than it has. If human trials and further testing had been done earlier, we might already have a treatment for SARS-CoV-2.

Drug Cocktails

Here's where things get a little trickier. Drugs have dangerous interactions. They're called "antagonistic effects." Two drugs that cause one's heart rate to increase may result in a deadly combination. However, drugs can also have a synergistic effect. A recent trial study suggests that hydrochloroquine, a close relative of chloroquine, along with azithromycin, might offer superior activity at fighting the viral infection over one drug alone (Gautret et al. 2020).

There is still unfortunately a lot of work to do, in order to make sure that the combination is safe and effective. This one trial is small, and suffers from some apparent flaws in its analysis of the results. Nobody should ever combine these drugs, on their own, and should only do so if prescribed by a doctor, which likely won't happen outside of drug trials for a while.

Further Reading

I'm still working on copying articles over from Medium, and plan on writing a number of articles here on Vocal, but for now, feel free to check out my "public health index" over at Medium to see what else I've written on these topics.