The covid-19 pandemic has become the worst global health crisis in the last century. Currently, the corona vaccine has been released in the world. But discovering a new and specific antiviral agent against SARS-CoV-2 requires a long and difficult schedule. Therefore, in this situation, the best thing to do is to use drugs that were previously used against other viral infections. One of these drugs is favipiravir, which was initially marketed as an anti-influenza drug in Japan .Favipiravir was first used in the center of the epidemic against SARS-CoV-2 in Wuhan. With the outbreak of the epidemic in Europe, this drug was approved for emergency use in Italy. And it is currently used in most of the countries affected by Covid-19. In June 2020, the drug received DCGI approval in India for mild to moderate Covid-19 infections .Favipiravir tablets along with remdesivir are antiviral drugs that are also seen in the treatment protocol of corona patients . Today, there are doubts about the effectiveness of this drug. Some news agencies report the removal of this drug from the treatment protocol. But it is still widely prescribed and consumed. It is better to know that the most suitable medicine for you is the one prescribed by the infectious disease doctor according to your personal conditions. As a result, avoid self-administration of this medicine and other medicines during the Corona period.
How does favipiravir tablet work?
Inside the body tissue, favipiravir tablets are converted into the active form of the drug and exert their antiviral effect through the following mechanisms:
It leads to the termination of protein synthesis in the virus.
This drug is placed in the RNA strand of the virus and prevents its further spread.
Recently, it has been shown that favipiravir in influenza infections can cause a lethal mutagenesis in the virus, making it a virulent drug.
What diseases is favipiravir used for?
Favipiravir inhibits 53 types of influenza viruses, including seasonal strains of type A such as H1N1 and B. It can also be used against drug-resistant strains of the virus, including M2 and NA inhibitors.
Sars Corona Virus (Covid-19)
By inhibiting virus enzymes, favipiravir causes easy entry of the drug into viral RNA. concluded that nucleoside analogues (such as favipiravir) are promising drugs in the treatment of COVID-19.
During the 2014 Ebola virus outbreak, favipiravir was one of the drugs shortlisted by the WHO. Studies have shown encouraging results for this drug. Favipiravir at an initial dose of 6000 mg followed by 2400 mg/day for 9 days was found to be effective in patients with moderate to high viremia. But in patients with more severe viremia, it does not have much effect. This dose appears to be well tolerated. A retrospective study also showed that patients treated with fipiravir had a better chance of survival against the Ebola virus.
In addition to the activity of favipiravir against influenza and Ebola viruses, it has been found that this drug has a therapeutic effect on RNA viruses such as yellow fever virus, hand-foot-mouth disease virus and Lassa virus, which causes viral hemorrhagic fever and encephalitis. (infection and inflammation of brain tissue).
Favipiravir 200 tablets interact with what drugs?
Drug interactions may change the way your medications work or increase your risk of serious side effects from favipiravir tablets. This list does not include all possible drug interactions. So, before taking Favipiravir 200, provide your internal physician with a list of all the medications you are using.
Examples of drugs that can interact with favipiravir 200 tablets are listed below
Pyrazinamide is a drug used to treat tuberculosis. The simultaneous use of pyrazinamide with favipiravir increases the level of uric acid. Regular checking of uric acid levels is recommended when these drugs are used together.
Repaglinide is an antidiabetic drug in the group of drugs known as meglitinide. Favipiravir inhibits the metabolism of repaglinide through the CYP2C8 pathway, thus increasing the concentration of this drug in the blood and also increasing the risk of its toxicity. Symptoms of poisoning include: hypoglycemia (severe reduction in blood sugar), headache, increased incidence of upper respiratory tract infections, etc.
Theophylline increases the blood level of favipiravir and may increase the risk of side effects of this drug.
Famciclovir is an antiviral drug that is used to treat infections caused by genital and facial herpes viruses, as well as shingles. It is also sometimes used in the treatment of people infected with the human immunodeficiency virus (HIV). If famciclovir is used simultaneously with favipiravir, the effectiveness of these drugs may decrease.
Acyclovir is an antiviral drug for the treatment of herpes lesions caused by the HSV virus, herpes zoster (shingles), and chicken pox. This disease may delay the conversion of favipiravir to the active part, thus reducing its antiviral effect.
Influenza virus vaccine (live/attenuated):
Antiviral drugs such as favipiravir may reduce the therapeutic effect of the flu vaccine. Therefore, avoid using these drugs in the period 48 hours before and 2 weeks after injecting the live flu vaccine.
What are the side effects of favipiravir?
Like all medicines, favipiravir 200 tablets can cause side effects. However, most people will have no side effects. In addition, if the doctor has prescribed this medicine for you, he has determined that the use of this medicine is more beneficial to you than its harm. Studies show that the following side effects have been observed in about 20% of patients who have received favipiravir (at a lower dose than allowed for Covid-19). Some of the common side effects of favipiravir are listed below:
Effect on endocrine glands:
Increased uric acid (hyperuricemia)
The use of favipiravir 200 tablets leads to a dose-dependent increase in blood uric acid. A systematic review was conducted by Pilkington et al. There is no reliable evidence that hyperuricemia caused by favipiravir tablets leads to clinical manifestations.
Important note: use with caution in gout. May increase uric acid.
Effect on the digestive system:
loss of appetite
Nausea and vomiting
Damage to liver cells
Increased liver enzymes.
Important points in the use of Favipiravir
Based on data obtained from animal reproduction studies, the use of favipiravir 200 mg tablets is contraindicated in pregnant patients. There is evidence that this drug has teratogenic potential and embryotoxicity. Before 200 mg tablets are prescribed for women of reproductive age, it is necessary to perform a pregnancy test. Women of childbearing potential should use effective contraception during treatment with the pill and for one week after the last dose.
Considerations for breastfeeding:
It is not known whether favipiravir is excreted in human milk. Based on data from animal studies, breastfeeding is prohibited during treatment with fipiravir.
The use of Favipiravir 200 mg tablets is prohibited during pregnancy and breastfeeding.
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