Hydroxychloroquine (HCQ) is an anti-malarial drug similar to chloroquine, one of the oldest and best-known anti-malarial drugs, but with lesser side-effects. It can be bought over the counter and is fairly inexpensive.
Also read | Hydroxychloroquine: publisher expresses ‘concerns’ about study
The drug shot to fame as it is shown to have shortened the time to clinical recovery of COVID-19 patients. However, many of these are in small lab-controlled testing and no proper human trials have been conducted to determine its efficacy.
A study in France enrolling 80 patients showed that hydroxychloroquine alone or in combination with azithromycin appeared to reduce virus levels quicker, as did a study in Wuhan — the epicentre of coronavirus outbreak — in which also it appeared to reduce the duration of severe illness. It's primarily these results that have prompted drug regulators in several countries including India to approve the drug in restricted settings.
Several scientists fault the design of these trials. Hydroxychloroquine is an interferon blocker, and works by diminishing the immune system's response to a viral infection. A hyperactive response by the immune system is said to be primarily responsible for pneumonia, also a fallout of a severe SARS-CoV-2 infection. This property of HCQ is what makes it useful in autoimmune disorders such as lupus and rheumatoid arthritis.
Also read | Despite lack of clinical evidence, demand surges for hydroxychloroquine as drug against COVID-19
The Indian Council for Medical Research (ICMR) has cleared HCQ to be used as a prophylaxis, or preventive medication, by doctors, nurses and other health staff. Union Health Ministry, last month, moved it to Schedule H1, which can be sold on prescription only. In the absence of better drugs and healthcare workers exposed to high levels of the virus, HCQ could in theory modulate their immune system's response to the virus and protect them. However, these dosages are also linked to instances of cardiac arrhythmia and liver damage.
Though now prescribed only for restricted groups, wide usage could mean other unknown complications surface and—in its ability to tune down the body's immune response—may actually handicap people's ability to fight the infection.
Even as the drug’s efficacy is not yet clinically proven, U.S. President Donald Trump has been a proponent of its use, calling it a “gamechanger”. He warned "retaliation" against India, if it didn't revoke the ban on its exports. India eventually allowed export of the drug.
Also read | More than 29 million hydroxychloroquine doses bought by U.S. have come from India, says President Trump
India produces 70 per cent of the world’s supply of hydroxychloroquine, according to Indian Pharmaceutical Alliance (IPA) secretary-general Sudarshan Jain, making it the biggest manufacturer. The country has a production capacity of 40 tonnes of HCQ every month, implying 20 crore tablets of 200 mg each. India gets the active pharmaceutical ingredient (API) that is used to manufacture HCQ from China and supplies so far have been steady.
Ipca Laboratories, Zydus Cadila and Wallace Pharmaceuticals are top pharma companies manufacturing HCQ in India.
