New Delhi: As India continues to use hydroxychloroquine both for treatment and prophylaxis of Covid-19 despite several studies questioning the efficacy of the drug in either role, an AIIMS Bhubaneswar study has flagged a possible prophylactic function of deworming drug ivermectin for the novel coronavirus.
The national Covid management guidelines do not advise the drug’s use. However, it has been in use for Covid treatment at AIIMS in the national capital right from the start of the pandemic and with satisfactory results, say doctors at India’s premier medical institute.
Ivermectin is an anti-parasitic drug. It acts by impeding the role of cell proteins that are hijacked by an invading pathogen and thus is conceived to have a role beyond the known, including against the SARS-CoV2 virus.
The pre-print study from Bhubaneswar earlier this week concluded: “Two-dose ivermectin prophylaxis at a dose of 300 μg/kg with a gap of 72 hours was associated 73% reduction of COVID-19 infection among healthcare workers for the following one-month. Further research is required before its large scale use.”
The drug was tested in 186 case-control pairs. The paper also made the point that the “use of hydroxychloroquine (HCQ) as chemoprophylaxis was used in India under the recommendation of a few experts with little evidence and lack of scientific data”.
Last month, the national task force on Covid discussed ivermectin in a meeting but decided against including it in the national clinical management protocol citing lack of enough evidence, according to health ministry officials who didn’t wish to be named.
AIIMS has been using ivermectin for Covid since 3 April
Ivermectin is normally used as a deworming medication. However, the drug is being used “from day one” at AIIMS, said Dr Anjan Trikha professor of anaesthesiology, pain and critical care, at the institute.
“We have been using it since 3 April and we are still using it — 12 mg for three days. Obviously we have had a good experience. That is why we have continued. We are using it because it is relatively safe, with chances of potential complications being less, and it is cheap,” said Trikha.
“There was also a study on prophylaxis but we are not using it institutionally for that purpose. Some people may choose to take it. We are using it in confirmed Covid cases. It is not approved for Covid but there are so many things that aren’t including monoclonal antibodies which President Donald Trump took,” he added.
Some studies have found that ivermectin is associated with reduced mortality in Covid patients, in some cases by up to 40 per cent.
A US study published in the journal Chest found: “In this multihospital retrospective cohort study, we observed a significant association of ivermectin with improved survival for patients admitted with COVID-19. This association also was seen in the subset of patients with severe pulmonary disease.”
It added, “These findings were confirmed after multivariate adjustment for comorbidities and differences between groups, and also in a propensity score-matched cohort. Similar to other studies, we noted that older age, cardiac disease, current or former smoking, more severe pulmonary involvement at presentation, higher WBC counts, and lower lymphocyte counts emerged as risk markers for in-hospital mortality.”
How it works
Studies have shown that ivermectin can stop viral replication in cell cultures (outside the body) within 24-48 hours using a mechanism that prevents viral proteins from invading the nucleus of the host cell and thus taking over its replication machinery.
The problem, however, is that the dosage that is required to achieve this effect is far more than what is approved for use in humans.
In its Covid treatment guidelines update in August, the National Institutes of Health in the US wrote that ivermectin has been shown to “inhibit the replication” of SARS-CoV-2 in cell cultures. “However, pharmacokinetic and pharmacodynamic studies suggest that achieving the plasma concentrations necessary for the antiviral efficacy detected in vitro would require administration of doses up to 100-fold higher than those approved for use in humans,” it said.
“Even though ivermectin appears to accumulate in the lung tissue, predicted systemic plasma and lung tissue concentrations are much lower than 2 µM, the half-maximal inhibitory concentration against SARS-CoV-2 in vitro,” it said.
“Ivermectin is not approved for the treatment of any viral infection, including SARS-CoV-2 infection. The FDA issued a warning in April 2020 that ivermectin intended for use in animals should not be used to treat COVID-19 in humans,” it added.