|Year : 2020 | Volume
| Issue : 2 | Page : 37-40
The broad-spectrum antiparasitic ivermectin against COVID-19
Nadia A El Dib1, Mona I Ali2
1 Department of Medical Parasitology, Faculty of Medicine, Cairo University, Cairo, Egypt
2 Department of Medical Parasitology, Faculty of Medicine, Beni-Suef University, Beni-Suef, Egypt
|Date of Submission||01-Sep-2020|
|Date of Decision||18-Oct-2020|
|Date of Acceptance||28-Oct-2020|
|Date of Web Publication||30-Dec-2020|
Mona I Ali
Department of Medical Parasitology, Faculty of Medicine, Beni-Suef University, Beni-Suef, 62521
Source of Support: None, Conflict of Interest: None
Ivermectin, the FDA-approved broad-spectrum antiparasitic drug, has recently shown excellent antiviral effects against many viral infections. This effect was especially important in the current pandemic infection of COVID-19. There are reports that ivermectin inhibited the replication of the virus in vitro in 48 h. Studies have been done on other viral infections and on this virus in vivo and in vitro. The results showed that it affects the viral replication by its effect on the protein transfer between the cytoplasm and nucleus inside the host cells. More information is still needed to approve its use in the treatment and prevention of COVID-19 pandemic, which will necessitate more studies to adjust the dose and mode of administration.
Keywords: COVID-19, SARS-CoV-2, importin, ivermectin, RNA viruses, viral inhibition, viral replication
|How to cite this article:|
El Dib NA, Ali MI. The broad-spectrum antiparasitic ivermectin against COVID-19. Kasr Al Ainy Med J 2020;26:37-40
| Introduction|| |
Ivermectin is a famous broad-spectrum anthelminthic therapy for animals and humans. It also has a potent effect when used for entomological infestation, for example, scabies, pediculosis , and myiasis . Most importantly, it has been implicated in malaria control programs by the WHO , as well as its antiviral effect against a wide range of viruses . Molecular structure is shown in [Figure 1].
Ivermectin is one of the members of a family of natural products ‘ivermectins,’ from soil actinomycetes. It was first isolated in 1970s from the fermented broth of the bacteria Streptomyces avermitilis .
Since 1980s, several trials have been carried out to synthetize ivermectin and related compounds mainly after fermentation of the soil microorganism. Milbemycin is one of the related groups without carbohydrates that has been isolated as well. Ivermectin was found to be very effective against a wide number of parasites, including helminths and arthropods affecting man and livestock, and also it is prepared as lotions and creams against head lice in Australia. It is believed that it causes paralysis of these invertebrate parasites. Ivermectin is used in tablet form to treat nematode infection as well as scabies and rosacea, a skin condition with redness and visible blood vessels on the face . The greatest effect of ivermectin is related to its famous use against onchocerciasis and river blindness in Africa.
After ivermectin was approved as antiparasitic agent by the FDA, it has shown a wide range of antiviral activity in vitro. It affects the RNA viruses and also shown great effect against DNA viruses in vitro and in vivo .
Ivermectin has attracted international attention for its use in the treatment of cases infected with COVID-19. In Peru, it was included in the national therapeutic guidelines for this pandemic. In Bolivia, there was a mass administration to 3 50 000 people for the treatment and prevention of COVID-19. Ivermectin market was restricted in Paraguay and Colombia for fear of mal-use .
Scientists suggest that the use of ivermectin against COVID-19 will need preclinical as well as clinical trials with enough funds to maintain the work .
A study was done in Latin America on 1408 PCR-confirmed COVID-19 hospitalized cases between the first of January and the end of March 2020. The data were collected from 169 hospitals in three continents. A single oral dose of ivermectin (150 μg/kg) was given to 704 cases, who were matched regarding their age, sex, race, and underlying morbidity, for example, history of smoking, obstructive lung disease, hypertension, diabetes, cardiac and coronary artery disease, and the taken medications including azithromycin, hydroxychloroquine, and corticosteroids. The group that was given ivermectin showed reduction in the need for mechanical ventilation and reduction in the death rate .
In Bangladesh, some scientists claimed that a mixture of ivermectin in a single oral dose with the antibiotic doxycycline cured COVID-19-positive cases in less than 7 days without any adverse effects. They were especially proud of this finding owing to low cost of the combination of drugs .
The mode of action of ivermectin against viral infections is still not very clear, but it appears that it stops the processes that allow proteins to move within the virus. These proteins would normally modify the body’s antiviral response, allowing the virus to replicate and enhance the infection [8-10].
A very nice and easy explanation of how the drug works was given by Dr Jans, who said, ‘The main way ivermectin works is to target a key molecule of our cells that helps the virus to proliferate. By stopping this, the virus replicates more slowly, and so our immune system has a better chance to mount the antiviral response and kill the virus. Giving this or any antiviral drug early, is thought to give the body the best chance of beating infection’ ,.
Members of the importin (IMP) superfamily of transporters of α-type and β-type are known to mediate the process of movement of protein between the cytoplasm and nucleus of the cells. This includes differentiation and development. Ivermectin was identified as one of the potent inhibitors of this process .
Wagstaff et al.  reported that ivermectin acts by inhibition of interaction between the HIV-1 integrase protein (IN) and the IMPα/β1 heterodimer responsible for IN nuclear import.
Other actions of ivermectin have been reported, but ivermectin has been shown to inhibit nuclear import of the host and viral proteins [14-16], including simian virus SV40 large tumor antigen and dengue virus (DENV) nonstructural protein 5 [10-13].
DENV was also proved to be affected by a single oral dose of ivermectin in Thailand .
Recently, Yang et al.  detected that ivermectin could dissociate the preformed IMPα/β1 heterodimer and prevent its formation. This was detected by binding to the IMPα armadillo repeat domain to affect IMPα thermal stability and α-helicity.
By using quantitative bimolecular fluorescence complementation, ivermectin was shown to inhibit NS5-IMPα interplay in cell context. All of these findings could restrict viral infections .
More studies showed that infection with RNA viruses, for example, DENV 1–4 , West Nile Virus  Venezuelan equine encephalitis virus , and influenza , was limited by the use of ivermectin.
These results were very promising as the virus responsible for the current COVID-19 (SARS-CoV-2), is a single-stranded positive-sense RNA .
Ivermectin is administered orally in the form of tablets or as an ethanolic extract. The bioavailability of the drug is affected by the ethanolic extraction and shows that it has a double availability as tablets or capsules. However, absorption was the same in all of these forms .
Ivermectin binds to plasma proteins with specific binding to serum albumin . It was observed that the drug absorption was inefficient in cases with malabsorption of proteins and other nutrients as in cases with disseminated strongyloidiasis. The blood concentration of the drug in such cases was found less than in other healthy cases, indicating a need for other alternative route of administration. Thus, in cases, who cannot absorb oral medication, it is necessary to use the parenteral route to introduce ivermectin (which is not licensed for use in humans) . The high lipid solubility of the drug makes it easily distributed in the body, especially in fatty tissue.
In vitro studies used a concentration of ivermectin in 2 µM. It led to inhibition of 50% of the proliferating viruses (IC50). This concentration was measured to be 35 times more than the highest concentration in blood, after the administration of the approved dose of ivermectin (200 µg/kg). It is referred to as the total plasma concentration .
Ivermectin reaches the lungs, which are important target organs in cases with COVID-19, in an unbound form when administered in humans. There is a specific transport protein that keeps the drug in the lung tissue in certain concentration. The concentration of the drug in human lung tissue is difficult to be measured. Experimental work on cattle showed that the drug concentration in the lungs reached three times the concentration of plasma level. However, the researchers claimed that the lung ivermectin concentrations does not reach the IC50 after oral administration of the approved dose in humans .
Researchers from Australia used the ivermectin to treat cases with COVID-19, although they were not completely convinced. There was news about trials in London and Maryland, USA, under special occasions after conducting nonpublished animal studies .
In Latin America, the drug is used against common intestinal helminths known to modulate the immune responses that might affect the viral clearance. It is believed that if the use of the drug is not monitored properly in areas where it should be used to treat other diseases, nonsupervised doses of veterinary formulas could lead to some problems in mass-treatment regimens for the eradication of river blindness. There is also the false feeling of being protected .
Although ivermectin is approved by the FDA and is currently widely used to treat many parasitic diseases, showing a wide safety profile for human use ,, yet cases show some common adverse effects, including diarrhea, nausea, dizziness, and drowsiness. Less commonly, lack of energy, abdominal pain, constipation, vomiting, tremors, rashes, and itching may occur. Ivermectin may also interact with some medicines, such as the blood-thinning drug warfarin, or increase the severity of some conditions such as asthma .
If ivermectin is going to be used as a potential therapy against COVID-19, there will be some important questions to be answered regarding what is the proper dose? How it is delivered? What about its safety during pregnancy? Does it prevent COVID-19 infection? Does it reduce the severity of the illness? Does it shorten the time to recovery? .
These are very important reasons to recommend carrying out more studies before the drug is approved for the treatment of this serious pandemic.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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