Sold under the brand name Plaquenil, hydroxychloroquine is one of the oldest drugs advised for the treatment, as well as prevention, of malaria. In the United States, the drug is available by prescription only. If left untreated, malaria could lead to severe complications, even death.

Apart from treating and preventing malaria, hydroxychloroquine has been found highly effective at treating autoimmune diseases called rheumatic arthritis and lupus. Rheumatoid arthritis is an inflammatory condition of joints, while lupus is one of the forms of ulcerative skin disease.

The U.S Food and Drug Administration (FDA) approved hydroxychloroquine in April 1955. Since then, it has become one of the widely prescribed malaria drugs. Many companies develop generic versions of this drug, which are much, much cheaper than Plaquenil.

Hydroxychloroquine is available in 200 mg potency, which is to be taken exactly as advised by a doctor. For malarial prevention, one needs to take 400 mg a week, initiating a couple of weeks before going to geographical areas where malaria is still considered an endemic. The drug should be continued for 4 weeks after leaving the area.

For malarial treatment, one needs to take hydroxychloroquine 200 mg (4 tablets) as a stat dose, then 200 mg (2 tablets) after 6 hours, and then 200 mg (2 tablets) after 24 hours and 48 hours of the first dose. For lupus and rheumatoid arthritis, the drug is prescribed once a day, depending on the patients’ age, response, and susceptibility.

What is the role of the drug in treating malaria?

Well, hydroxychloroquine does belong to the class of drugs called antimalarials, just like chloroquine (Aralen), but its exact mechanism of action is unclear or poorly understood. It is presumed that the drug prevents malarial parasites from multiplying in the red blood cells (RBCs). Malarial parasites enter the RBCs, proliferate, and breakdown hemoglobin. The drug prevents the parasites from breaking down hemoglobin.

Hydroxychloroquine has been found effective against most of the malarial parasites, including Plasmodium vivax, malariae, ovale, and some strains of falciparum. The drug is also known to prevent inflammation caused by rheumatoid arthritis and lupus.

Hydroxychloroquine has been touted as one of the effective medications for COVID-19; however, based on recent findings, the FDA has revoked the approval of the drug for treating the infection caused by the new coronavirus. The agency stated that the drug is unlikely to be effective at treating COVID-19.

The FDA found that hydroxychloroquine raised cardiac concerns in many patients. During COVID-19 treatment trials, the drug was found to cause arrhythmia – a heart rhythm disorder – in most patients, promoting researchers to end the trails. While additional trials may continue, the FDA determined the approval was no longer appropriate.

The conclusion of this post is hydroxychloroquine does play a key role in treating and preventing malaria by disallowing malarial parasites to enter RBCs; however, the exact working of the drug is unknown and a bit complicated.