The Centers for Disease Control and Prevention (CDC) has just removed guidance for doctors from its website on prescribing two controversial anti-malarial drugs, hydroxychloroquine and chloroquine, which US President Donald Trump has claimed to be potentially effective treatment for COVID-19.

The drugs, however, have not been proven to treat the virus and the US FDA is yet to approve any drugs or other therapeutics to treat COVID-19. Updated guidance from the CDC has removed previously issued dosage recommendations. Without proper evidence that hydroxychloroquine is effective against COVID-19, it's unclear what dosages can be administered safely, based on a report. "There are no US Food and Drug Administration (FDA)-approved drugs specifically for the treatment of patients with COVID-19. At present clinical management includes infection prevention and control measures and supportive care, including supplementary oxygen and mechanical ventilatory support when indicated. An array of drugs approved for other indications as well as several investigational drugs are being studied in several hundred clinical trials that are underway across the globe," the page now reads.

The CDC mentions that hydroxychloroquine is currently under investigation in clinical trials for "pre-exposure or post-exposure prophylaxis of SARS-CoV-2 infection, and treatment of patients with mild, moderate, and severe COVID-19." The page further added, "Although optimal dosing and duration of hydroxychloroquine for treatment of COVID-19 are unknown, some U.S. clinicians have reported anecdotally different hydroxychloroquine dosing."

According to three peer-reviewed journal articles, hydroxychloroquine and chloroquine are oral prescription drugs that have been used for treatment of malaria and certain inflammatory conditions. Chloroquine has been used for malaria treatment and chemoprophylaxis, and hydroxychloroquine is used for treatment of rheumatoid arthritis, systemic lupus erythematosus and porphyria cutanea tarda. Both drugs have in-vitro activity against SARS-CoV, SARS-CoV-2, and other coronaviruses, with hydroxychloroquine having relatively higher potency against SARS-CoV-2.