Antiviral drugs : Classification, Vaccination

Antiviral drugs are a class of medication used for treating viral infections.

Most antivirals target specific viruses, while a broad spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead they inhibit their development.

Antiviral drugs are one class of antimicrobials, a larger group which also includes antibiotic (also termed antibacterial), antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies.

Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections.

VACCINATIONS

While most antivirals treat viral infection, vaccines are a preemptive first line of defense against pathogens.

Vaccination involves the introduction (i.e. via injection) of a small amount of typically inactivated or attenuated antigenic material to stimulate an individual’s immune system.

The immune system responds by developing white blood cells to specifically combat the introduced pathogen, resulting in adaptive immunity.

CLASSIFICATION

1.Anti-Herpes virus

Idoxuridine, Trifluridine, Acyclovir, Valacyclovir, Famciclovir, Ganciclovir, Valganciclovir, Cidofovir, Foscarnet, Fomivirsen

2. Anti-Influenza virus

Amantadine, Rimantadine, Oseltamivir, Zanamivir

3. Anti-Hepatitis virus/ Nonselective antiviral drugs

Primarily for hepatitis B– Lamivudine, Adefovir dipivoxil, Tenofovir
Primarily for hepatitis C: Ribavirin, Interferon alpha

4. Anti-Retrovirus

(a) Nucleoside reverse transcriptase inhibitors (NRTIs): Zidovudine (AZT),

Didanosine, Stavudine, Lamivudine, Abacavir, Emtricitabine, Tenofovir

(b) Nonnucleoside reverse transcriptase inhibitors (NNRTIs): Nevirapine, Efavi renz, Delavirdine

(d) Entry (Fusion) inhibitor: Enfuvirtide

(e) CCR5 receptor inhibitor: Maraviroc (f) Integrase inhibitor: Raltegravir

DRUGS KNOWLEDGE IN DETAIL

Anti herpes virus

Antiviral agents used to treat herpes simplex virus infections are nucleoside analogs.

Acyclovir is the antiviral most commonly used to treat herpes simplex virus (HSV) infections.

Oral therapy is effective for non-life-threatening herpes simplex virus infections (eg, primary orolabial, genital), and can be useful in the suppression of recurrent genital herpes simplex virus infections to diminish viral shedding and decrease rates of clinical recurrences.

Intravenous (IV) acyclovir is indicated for the treatment of encephalitis, any form of neonatal disease, severe infection in patients who are immunocompromised, and occasionally for cases of severe orolabial or genital disease.

Trifluridine (also called trifluorothymidine or TFT) used primarily on the eye. It was sold under the trade name Viroptic .

Acyclovir treats cold sores around the mouth (caused by herpes simplex), shingles (caused by herpes zoster), and chickenpox.

This medication is also used to treat outbreaks of genital herpes. In people with frequent outbreaks, acyclovir is used to help reduce the number of future episodes.

However, it is not a cure for these infections.

The viruses that cause these infections continue to live in the body even between outbreaks. Acyclovir decreases the severity and length of these outbreaks.

Idoxuridine a modified form of deoxyuridine, similar enough to be incorporated into viral DNA replication.

It is used only topically due to cardiotoxicity. Initially developed as an anticancer drug, idoxuridine became the first antiviral agent in 1962.

Fomivirsen (brand name Vitravene) is an antisense antiviral drug that was used in the treatment of cytomegalovirus retinitis (CMV) in immunocompromised patients, including those with AIDS. It was administered via intraocular injection.

Cidofovir brand name Vistide, is an injectable antiviral medication primarily used as a treatment for cytomegalovirus retinitis in people with AIDS.

Cidofovir was approved for medical use in 1996.

Valganciclovir, sold under the brandname Valcyte among others, is an antiviral medication used to treat cytomegalovirus infection in those with HIV/AIDS or following organ transplant. It is often used long term as it only suppresses rather than cures the infection. Valganciclovir is taken by mouth.

Ganciclovir is an antiviral medication used to treat cytomegalovirus infections. A prodrug form with improved oral bioavailability has also been developed.

This was approved for medical use in 1988.

Famciclovir used for the treatment of various herpesvirus infections, most commonly for herpes zoster. It is a prodrug form of penciclovir with improved oral bioavailability. Famciclovir is marketed under the trade name Famvir.

Anti-influenza virus

Influenza is a very common contagious disease that carries significant morbidity and mortality.

Treatment with antiviral drugs is available, which if administered early, can reduce the risk of severe complications.

However, many virus types develop resistance to those drugs, leading to a notable loss of efficacy. There has been great interest in the development of new drugs to combat this disease.

Amantadine is used to treat or prevent influenza A in adults and children.

Amantadine may not be effective during every flu season because certain strains of the virus may be resistant to amantadine.

Amantadine should not be used in place of getting a yearly flu shot. The Centers for Disease Control recommends an annual flu shot to help protect you each year from new strains of influenza virus.

NOTE -Amantadine is also used to treat Parkinson’s disease and “Parkinson-like” symptoms such as stiffness or tremors, shaking, and repetitive uncontrolled muscle movements that may be caused by the use of certain drugs.

Rimantadine is used to prevent or treat a certain type of flu virus (influenza A). If you have been infected with the flu, this medication may help make your symptoms less severe and shorten the time it will take you to get better.

Taking rimantadine if you have been or will be exposed to the flu may help to prevent you from getting the flu. This medication is an antiviral that is believed to work by stopping the growth of the flu virus. This medication is not a vaccine. To increase the chance that you will not get the flu, i is important to get a flu shot once a year at the beginning of every flu season, if possible.

Oseltamivir is used to treat symptoms caused by the flu virus (influenza). It helps make the symptoms (such as stuffy nose, cough, sore throat, fever/chills, aches, tiredness) less severe and shortens the recovery time by 1-2 days.

Zanamivir is used to treat symptoms caused by the flu virus (influenza) if you have had symptoms for 2 days or less. It helps lessen symptoms (such as stuffy nose, cough, sore throat, fever/chills, headache, body aches, tiredness) and shortens the recovery time by about 1 to 2 days.

Anti-hepatitis virus

Hepatitis B

Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV) that affects the liver; it is a type of viral hepatitis. It can cause both acute and chronic infection.

Many people have no symptoms during the initial infection. In acute infection, some may develop a rapid onset of sickness with vomiting, yellowish skin, tiredness, dark urine and abdominal pain.

Often these symptoms last a few weeks and rarely does the initial infection result in death. It may take 30 to 180 days for symptoms to begin.

Tenofovir oral tablet is available as generic drug and as a brand-name: Viread, Vemlidy.

Tenofovir comes in two forms: an oral tablet and an oral powder. Tenofovir oral tablet is approved to treat HIV infection and chronic hepatitis B virus infection.

This medication is used to treat a chronic viral infection of the liver (hepatitis B) in people 12 years of age and older.

It works by slowing the growth of the virus, helping to lower the amount of virus in your body. It is not a cure for hepatitis B and does not prevent the passing of hepatitis B to others.

This drug is used with other HIV medications to help control HIV infection.

Lamivudine helps to decrease the amount of HIV in your body so your immune system can work better. This lowers your chance of getting HIV complications (such as new infections, cancer) and improves your quality of life. Lamivudine belongs to a class of drugs known as nucleoside reverse transcriptase inhibitors- NRTI.

Adenovir his medication is used to treat a chronic viral infection of the liver (hepatitis B) in people 12 years of age and older. It works by slowing the growth of the virus, helping to lower the amount of virus in your body. It is not a cure for hepatitis B and does not prevent the passing of hepatitis B to others.

Hepatitis C

Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis.

During the initial infection people often have mild or no symptoms.

Occasionally a fever, dark urine, abdominal pain, and yellow tinged skin occurs. The virus persists in the liver in about 75% to 85% of those initially infected.

Early on chronic infection typically has no symptoms. over many years however, it often leads to liver disease and occasionally cirrhosis. In some cases, those with cirrhosis will develop serious complications such as liver failure, liver cancer, or dilated blood vessels in the esophagus and stomach.

Ribavirin, also known as ribavirin, is an antiviral medication used to treat RSV infection, hepatitis C and some viral hemorrhagic fever.

For hepatitis C, it is used in combination with other medications such as simeprevir, sofosbuvir, peginterferon alfa-2b or peginterferon alfa-2a

Common side effects include feeling tired, headache, nausea, fever, muscle pains, and an irritable mood. Serious side effects include red blood cell breakdown, liver problems, and allergic reactions. Use during pregnancy results in harm to the baby. Effective birth control is recommended for both males and females for at least 7 months during and after use.

Interferon alfa (INN) or HulFN-alpha-Le, trade name Multiferon, is a pharmaceutical drug composed of natural interferon alpha (IFN-a) obtained from the leukocyte fraction of human blood following induction with Sendai virus. Interferon alfa contains several naturally occurring IFN-a subtypes and is purified by affinity chromatography.

Anti-retrovirals; HIV and AIDS Drugs

HIV medications can help lower your viral load, fight infections, and improve your quality of life.

They can lower your chances of transmitting HIV but if you take them incorrectly, you can still give HIV to others. They’re not a cure for HIV.

The goals for these medicines are to:

Control the growth of the virus and Improve how well your immune system works.
Slow or stop symptoms
Prevent transmission of HIV to others.

Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs)

NRTIs force the HIV virus to use faulty versions of building blocks so infected cells can’t make more HIV.

This drug is used with other HIV medications to help control HIV infection.

Zidovudine It helps to decrease the amount of HIV in your body so your immune system can work better. This lowers your chance of getting HIV complications (such as new infections, cancer) and improves your quality of life.

Emtricitabine , didanosine and Abacavir is used with other HIV medications to help control HIV infection. And works same as Zidovudine

Stavudine is not a cure for HIV infection.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

These are antiviral agents that bind non-competitively to HIV-1’s reverse transcriptase and prevents viral RNA conversion to DNA. They are used to treat human immunodeficiency virus (HIV infection) and acquired immune deficiency syndrome (AIDS).

Nevirapine (NVP), marketed under the trade name Viramune . It is generally recommended for use with other antiretroviral medication. It may be used to prevent mother to child spread during birth but is not recommended following other exposures. It is taken by mouth.

Efavirenz can cause serious, life threatening side effects. These include serious mental health problems, liver problems, and severe rash.

Protease inhibitors

These are a class of antiviral drugs that are widely used to treat HIV/AIDS and hepatitis C. Protease inhibitors prevent viral replication by selectively binding to viral protease (e.g. HIV-1 protease) and blocking proteolytic cleavage of protein precursors that are necessary for the production of infectious viral particles.

Ritonavir (RTV), sold under the trade name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART).

Often a low dose is used with other protease inhibitors. It may also be used in combination with other medications for hepatitis C.

Atazanavir sold under the trade name Reyataz among others. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needlestick injury or other potential exposure. It is taken by mouth once a day.

Indinavir (IDV; trade name Crixivan, used as a component of highly active antiretroviral therapy to treat HIV/AIDS. It is soluble white powder administered orally in combination with other antiviral drugs.

Saquinavir (SQV), sold under the brand names Invirase and Fortovase. Typically it is used with ritonavir or lopinavir/ritonavir to increase its effect. It is taken by mouth.

Nelfinavir (NFV; brand name Viracept) used in the treatment of the human immunodeficiency virus (HIV). almost always used in combination with other antiretroviral drugs. Nelfinavir has been tested to treat COVID-19.

Amprenavir is a synthetic derivative of hydroxyethylamine sulfonamide that selectively binds to and inhibits human immunodeficiency virus (HIV) protease.

Lopinavir This combination product contains two medications: lopinavir and ritonavir.

It helps to decrease the amount of HIV in your body so your immune system can work better. Ritonavir increases (“boosts”) the levels of lopinavir. This helps lopinavir work better.

Enfuvirtide (INN) is an HIV fusion inhibitor, the first of a class of antiretroviral drugs used in combination therapy for the treatment of HIV 1 infection. It is marketed under the trade name Fuzeon (Roche).

Maraviroc, brand-name Selzentry and Celsentri, used in the treatment of HIV infection.

It also appeared to reduce graft-versus-host disease in patients treated with allogeneic bone marrow transplantation for leukemia.