antiviral drugs mechanism of action #all drugs mao

antiviral drugs mechanism of action #all drugs mao

antiviral drugs mechanism of action

The virus does not take only nutrition from the host cell but also a synthesise a new particle through metabolic machinery. The viral chemotherapy is very difficult it should be required interference with their cellular metabolism in the host cell. that’s why here, further discuss the antiviral drugs mechanism of action in details.

In the antiviral drugs mechanism of action various classes drugs have their own mechanism of action. In antiviral drugs 4 major class.

  1. Antiherpes agents
  2. Antiretroviral agents
  3. Anti-influenza drugs
  4. Other antiviral drugs

1. antiheres agents:

[acyclovir, fancyclovir, vancyclovir, penciclovir, ganciclovir, foscarnet, idoxuridine]

In antiviral drugs mechanism of action, All antiherpes agents are act against the herpetic infection. Most common drugs used as antiherpes agents are
·        Acyclovir, vancyclovir, penciclovir, famciclovir, ganciclovir
·        Idoxuridine & foscarnet.

ACYCLOVIR: (antiviral drugs mechanism of action)

In antiviral drugs mechanism of action, acyclovir is purine nucleotide analogues that act as an antiherpes activity.

Acyclovir is most effective against this type of herpes infection,

HSV -1: herpes labialis, herpes encephalitis, herpes oesophagitis
HSV -2: genital herpes 
VZV (varicella-zoster virus): herpes zoster, chicken pox.

HSV thymidine kinase acts on the acyclovir and produces acyclovir monophosphate a further cellular enzyme acts on the acyclovir monophosphate and produce acyclovir diphosphate than further acyclovir diphosphate are converted into acyclovir triphosphate with the help of a cellular enzyme.

Than acyclovir triphosphate is inhibiting viral replication and also inhibit viral synthesis. So, the triphosphate derivatives are also a inhibit synthesis of viral DNA. And inhibit viral replication.

Acyclovir is highly potent drugs. the therapeutic index of acyclovir is high and produces low toxicity.

Use and adverse effect of acyclovir:

Acyclovir is administered by oral, i.v and topical administration.  But its oral bioavailability is very less. Its also used in different types of herpes infection & produce some common GI side effect but in a high dose that produces the tremor, nephrotoxicity, convulsion & etc.

VANCYCLOVIR (antiviral drugs mechanism of action)

It’s a prodrug of the acyclovir (ester prodrug).

In intestine and liver, vancyclovir are completely converted in acyclovir ➞ to intracellular activation acyclovir is converted in acyclovir triphosphate ➞ it’s affect the HSV 1 & 2, VZV & hepatitis B virus. ® inhibit the DNA synthesis and also inhibit viral replication.

Use and adverse effect of vancyclovir:

Vancyclovir is used in genital herpes, herpes zoster, orolabial herpes. The adverse effect of vancyclovir is nausea, vomiting and some skin rashes. In a high dose of acyclovir, some CNS symptoms are produced.

FNACYCLOVIR (antiviral drugs mechanism of action)

It’s a prodrug of the penciclovir (ester prodrug)

fancyclovir is converted to penciclovir  to also a pencylovir are converted to penciclovir triphosphate  that’s same as a vancyclovir inhibit the HSV 1 & 2, VZV and hepatitis B virus DNA synthesis  so, inhibit the DNA replication of the virus.

Use and adverse effect of fancyclovir:

It's used as an alternative of the acyclovir for orolabial herpes, genital herpes & herpes zoster. Early treatment of the herpes zoster that reduces the duration of post hepatic neuralgia. Some common side effect of fancyclovir are vomiting, diarrhoea, nausea & headache.

IDOXURIDINE (antiviral drugs mechanism of action)

Idoxuridine is 5 – iodo – 2 – deoxyuridine (IURD). Idoxuridine is first pyrimidine antimetabolite that used in antiviral agents.

Idoxuridine work as a thymidine analogues. It's incorporate with DNA. So, the faulty DNA are breakdown easily. It's effective against the DNA virus. Its inhibit the DNA synthesis. that’s why viral replication is also a decrease.    

Use and adverse effect of idoxuridine:

Idoxuridine eye drops are very effective than acyclovir eye ointment. It's also topically used in HSV keratoconjunctivitis. Some side effect produces like, irritation, itching, swelling and pain. Idoxuridine use is restricted to superficial dendritic keratitis when its rapid action is required. With idoxuridine eye drops ocular irritation produce.

antiviral drugs mechanism of action #all drugs mao

2 antiretroviral agents:

In antiviral drugs mechanism of action, antiretroviral is a most important agents to understand its mechanism of action because they used in the treatment of AIDS.

Anti retrovirus is acted against the human immune deficiency virus (HIV virus). These agents are useful in acquired immunodeficiency syndrome or ARC (aids-related complex).

Various classes of antiretroviral drugs are,

  •         Nucleotide reverse transcriptase inhibitor
  •         Non – nucleotide reverse transcriptase inhibitor
  •         Protease inhibitor
  •         Fusion inhibitor  
  •         Integrase inhibitor

Nucleoside reverse transcriptase inhibitors, protease inhibitor and integrase inhibitor are used in infection of HIV 1 and HIV 2. Where, non- nucleotide reverse transcriptase inhibitor is used in HIV – 1 infection.

(a) nonnucleotide reverse transcriptase inhibitors: (antiviral drugs mechanism of action) 

[zidovudine, stavudine, didanosine, lamivudine, zalcitabine, abacavir, tenofovir]

These drugs are entering the HIV – infected cells → they are converted to active triphosphate from cellular kinase → competitively they inhibit the HIV reverse transcriptase → they are also incorporate to growing viral DNA. → and in the last termination of DNA chain elongation.

Here, first, understand the life cycle of HIV. Then understand how all drugs affect the HIV cycle.

HIV LIFE CYCLE: (a most important part of antiretroviral agent)

First of all entry or fusion inhibitor in the cell membrane → after entering the cell membrane uncoating the viral RNA. → with the help of the reverse transcriptase single-strand, viral RNA is converted to double-strand proviral DNA. → this double-strand DNA virus is integrated with the host DNA cell. → with the help of transcription, it converts the viral mRNA. → viral mRNA is produced by viral proteins with the help of the translation process.
After that, HIV protease enzyme is release and maturation of the host cell and host cell are converted to HIV cell. once it’s converted it doesn’t cure but here, all drugs are used to prevent the HIV virus infection.


In the antiviral drugs mechanism of action zidovudine is prototype drugs of nucleotide reverse transcriptase inhibitors. Zidovudine is thymidine analogues. It’s a first antiretroviral drug used in HIV infection. It's effective against HIV 1 and HIV 2.

It’s not a cure an HIV infected cell but also a prevent its uninfected cell.

Understand a zidovudine mechanism first keep in mind HIV life cycle. Zidovudine triphosphate inhibits the reverse transcriptase. So, inhibit the double-strand DNA viral.

Also, it inhibits the integrase inhibitor and final stages that do prevent the cell maturation and release. Zidovudine are prevented the infection of the new cell. but in proviral that no any effect produces. Because proviral DNA is already integrated into the host cell.

Zidovudine is effective in orally, well absorbed from the GI tract. Its metabolise by the glucuronide conjugation and also excreted in the urine.

Use and side effect if zidovudine:

Combination of other antiretroviral drugs zidovudine are used in HIV infection. Zidovudine is preventing the vertical transmission of HIV. Also used in post-exposure prophylaxis.

Many common side effect like bone marrow suppression, neuropaenia and anaemia are produced. Also, nausea, vomiting, headache, abdominal discomfort, insomnia What Is Insomnia - Meaning, Symptoms, Treatment, Medication are produce. In long term therapy, it causes a myopathy, hepatotoxicity, fatigue and lactic acidosis.


In antiviral drugs mechanism of action, this all drugs has the same mechanism of action.

This all drugs have transported into the cells and activated to its respective triphosphate forms ® that inhibit the HIV reverse transcriptase ® so, don’t integrated with the host cell  ® not produce the viral protein  ® finally DNA chain is terminated.

They all are effective in orally. In this drugs lamivudine are commonly used in antiretroviral therapy because of low toxicity and low efficacy.

 Also, emtricitabine are least toxic antiretroviral drugs.

Stavudine with didanosine are combined are not safe because increase the risk of pancreatic, lactic acidosis and peripheral neuritis.

Abacavir is also produced some side effect like, hypersensitivity reaction.

(b) Non – nucleotide reverse transcriptase inhibitors: (antiviral drugs mechanism of action)

[nevirapine, delvirapine, tenofovir]

Non – nucleotide reverse transcriptase inhibitors are highly active against HIV – 1 virus but it's not any effect produce on HIV – 2 infection. Its directly inhibit the reverse transcriptase enzyme. So, they finally terminate the DNA chain.

They do not produce any cross-resistance with nucleotide reverse transcriptase inhibitors. Also the combination of both drugs (NNRTIs and NRTIs) is used in the treatment of AIDS.

Some adverse effect produces like GI effect (nausea, vomiting), skin rashes and CNS disturbance (headache, confusion, bad dream, insomnia.


In antiviral drugs mechanism of action, this all drugs are directly bound to the reverse transcriptase enzyme and also a inhibit their function. So, no any integrated with the host cell and finally terminated the maturation of cell.

Nevirapine is completely absorbed by the GI tract. Also a cross the blood-brain barrier and placenta. Nevirapine is also secreted in breast milk. Metabolise in the liver and excreted through urine.

The common side effect Is skin rashes and also a sometimes, hepatotoxicity are produced.

efavirenz is administered once daily and has a long duration of action. Some side effect produces like skin rashes and CNS side effect.

(c) Protease inhibitors : (antiviral drugs mechanism of action)

[saquinavir, ritonavir, indinavir, neflinvir, lopinavir]

all the protease inhibitors are the same mechanism of action produce like this,

All the protease inhibitors inhibit the HIV protease enzyme. Due to this enzyme are inhibited prevent the cleavage of the viral polypeptide ® final functioning of HIV cell cycle are terminated. ®
Produce an immature or non – infection viral cell. that is no further effect produce.
Protein inhibitor is given orally with reverse transcriptase inhibitors. Metabolise in the liver. Some common side effect produces like, nausea, vomiting and diarrhoea. Also produce lipodystrophy, insulin resistance, diabetes, skeletal muscle wasting.

Indinavir are specially produce some side effect like hyperbilirubinaemia and nephrolithiasis. Also, a good hydration can be reduced the incidence of the nephrolithiasis.

Ritonavir inhibits the cytochrome P 450. It's used in both HIV 1 and HIV 2 infection because it inhibits both proteases.

That is used with other protease inhibitors it can boost the protease inhibitor regimen. Its increase the bioavailability and half-life of other drugs. Nelfinavir are not combined with ritonavir.

(d) Fusion inhibitors (antiviral drugs mechanism of action)

[efvuridine, maraviroc]


It is prevent the entry of HIV 1 membrane with the host cell membrane. In starting block the viral entry into a host cell. so, no produce any further step preventing because starting entry is blocked.
Efvuridine is administered through subcutaneously. Its doesn’t exhibit cross-resistance with other reverse transcriptase and protease inhibitors. In infection site, some common side effect produces like pain and erythema.


It is a CCR 5 chemokine antagonist that inhibits the CCR 5 topic strain to host HIV cell. it is given orally. Some Adverse effect produces like, malaria, cough, arthralgia, diarrhoea and hepatotoxicity.

(e) Integrate inhibitors:



Raltegravir are also a inhibit the integrase enzyme. ® That block the integration of the viral DNA with the host DNA. Raltegravir are generally well tolerated. Also, some minor side effect produces like, nausea, headache & fatigue. Raltegravir are also effective against both HIV 1 and HIV 2.

3. anti-influenza drugs:

[amantadine, rimantadine, zanamivir, oseltamivir]

In antiviral drugs mechanism, fo action anti-influenza agents are useful in the treatment of viral infection.

AMANTADINE: (mechanism of action)

That is a unique tricyclic amine. Its also produce anti – parkinsonism effect. Its inhibit the influenza A virus replication. But, in influenza B that is not affected ® The antiviral activity of amantadine is strain-specific.

Its act on both early and late stages like uncoating stage or viral assembly in viral replication ® Both stages its effective. Thus finally they prevent the viral replication.  

amantadine is well absorbed in GI tract and excreted unchanged in the urine.

Use and side effect of amantadine:

Amantadine is also used for parkinsonism & prophylaxis. used in the treatment of influenza A virus infection. Some common side effect produces like, nausea, headache, epigastric discomfort, insomnia, confusion, hallucinogen and hypotension.

Amantadine is contraindicated in pregnancy due to the teratogenic effect.

RIMANTADINE: (mechanism of action)

Rimantidine is methyl derivatives of amantadine. It is more potent and longer acting. Rimantadine is better tolerated than parent drugs. the mechanism of action is similar to the amantadine. It's also a well absorbed in the GI tract and metabolized in liver and excreted in urine.

OSEITAMIVIR: (mechanism of action)

Oseltamivir are inhibit the influenza A and B virus. That also an interfering with the release of virus from the infected cell. used in prevention of influenza virus. (bird flu and swine flu). Some adverse effect produces nausea, vomiting and abdominal discomfort.

ZANAMIVIR: (mechanism of action)

In antiviral drugs mechanism of action, zanamivir drugs mechanism of action is similar to the oseltamivir. Its administered through inhalation. The oral bioavailability of zanamivir is low. Some adverse effect produces like dizziness, bronchospasm and headache. Should not prescribe Airway disease patients.

3. other antiviral agents:

[interferons, ribavirin]


IN other antiviral drugs mechanism of action interferon are most important. Its produce by the infected cell through recombinant DNA technology. Mostly three types of interferons like a, β and γ. This three types of interferons are produced an antiviral activity.

Interferons are bind to the specific cell surface receptor and also affect its viral replication, synthesis of viral mRNA. Interferons are inhibiting the translation and transcription of the cell. it inhibits the many RNA and DNA virus. But, only INFa2A and INFa2B are available for clinical used. They produce by the recombinant DNA technology. This is administered through i.m or s.c.

Use and adverse effect of interferon:

Interferon a are used for the treatment of hepatic infection in the immunosuppression, also used in venereal warts. It is used in hepatitis B and C.

Interferons are also used in follicular lymphoma, cutaneous T- cell lymphoma, myeloid leukaemia and multiple myeloma.

Interferons produce some common side effect like fatigue, aches, fever, dizziness, anorexia, nausea and visual disturbance. Its produce a neurotoxicity and myelosuppression. Interferon are produced some other side effect like hypothyroidism, hyperthyroidism, hypotension, alopecia and some liver dysfunction.

RIBAVIRIN: (mechanism of action)

In antiviral drugs mechanism of action, ribavirin is a purine nucleotide analogue. It's effective against influenza A & B and other DNA & double-stranded RNA viruses. Ribavirin monophosphate is inhibited the cellular enzyme. 

That cellular enzyme needed for synthesis of nucleic acid and guanosine triphosphate (GTP). Ribavirin triphosphate inhibits the viral mRNA synthesis.  

Ribavirin is administered in orally or i.v route. its metabolize in liver and excreted in urine.

Use and adverse effect of ribavirin:

It's effective against the infection of DNA and RNA. Ribavirin used in Treatment of parainfluenza, influenza, measles, adenovirus. Oral ribavirin is used in the treatment of chronic hepatitis C infection.

Some common side effect produces like, irritation, cough, nausea, tiredness, anaemia and insomnia. Also, respiratory irritation and conjunctival irritation produce. It produces a teratogenic, mutagenic and gonadotoxic toxic effect. So, not given in during pregnancy.

In antiviral drugs mechanism of action, a various different mechanism through drugs inhibits the viral infection. Its majorly 4 class of drugs here, discuss. I hope you will be like these articles. If you like this, comment out.

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