Antiviral Agents Viruses - The target of antiviral drugs.

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Antiviral Agents Antiviral Agents Viruses - The target of antiviral drugs

Transcript of Antiviral Agents Viruses - The target of antiviral drugs.

Page 1: Antiviral Agents Viruses - The target of antiviral drugs.

Antiviral AgentsAntiviral Agents

Viruses - The target of antiviral drugs

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Estimated number of people in the world living with HIV/AIDS in 2008(total world-wide infected is 23 million; 25 million died from AIDS from 1981-2006 )

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Overview of VirusesOverview of Viruses

Obligate intracellular parasites

Replication dependent on synthetic processes of host cell

Smallest, most primitive living thing

Viruses consist of genetic materials (DNA or RNA) surrounded by a protective coat of protein

Genome of most viruses consist of small genomes from 3.2 to 800 kbp

There is more genetic diversity among viruses than in all the rest of the Animal, Plant & Bacterial kingdoms

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Baltimore classification of virusesBaltimore classification of viruses

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I: dsDNA viruses Herpesviridae (HSVI-II, VZV, CMV)Papillomavirus (HPV)

II: ssDNA viruses Parvoviridae

III: dsRNA viruses Rotavirus

IV: (+)ssRNA viruses Hepatitis C virus, Yellow fever virus

V: (−)ssRNA viruses Influenzavirus A, Influenzavirus B, Ebola virus, Measles virus, Mumps virus, Rabies virus, Respiratory Syncytial Virus (RSV)

VI: ssRNA-RT viruses HIV

VII: dsDNA-RT viruses Hepadnaviridae (hepatitis B virus)

Baltimore classification of virusesBaltimore classification of viruses

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Some human diseases caused by viruses Some human diseases caused by viruses AIDS Burkitt's lymphoma

chicken pox colds

Colorado tick fever dengue

encephalitis fever blisters

genital warts gastroenteritis

genital herpes German measles

hepatitis influenza

leukemia liver cancer

measles mononucleosis

mumps oral herpes

polio rabies

shingles smallpox

virus hemorrhagic fever warts

yellow fever

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Antiviral AgentsAntiviral AgentsGeneral comments:Restricted spectrum compared to antibioticsNo standardized in vitro susceptibility testsMost inhibit viral replication; cure depends on host

immune system to eradicateMany need to be activated by viral and cellular

enzymes before exerting antiviral effectCurrent antiviral drugs do not eliminate non-

replicating or latent virusSingle nucleotide mutations in target viral protein

enough to cause drug resistance

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Chapter 43Chapter 43

•Adefovir dipivoxil (Hepsera)•Lamivudine (Epivir)

Drugs for Viral Hepatitis

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Drugs for Viral Hepatitis

Adefovir dipivoxilLamivudine

EmtricitabineTenofovirAbacavir

AmantadineRimantadine

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Antiviral drug classificationAntiviral drug classification

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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Antiviral drug classificationAntiviral drug classification

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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Human herpesviridae infections

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

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a. Nucleoside Analogsa. Nucleoside Analogs

General Mechanism of Action:Taken up by host cellsMost converted by viral and cellular enzymes to the active

triphosphate formThe triphosphate form inhibits:

DNA polymeraseReverse transcriptaseRNA polymerase

Additionally, some antivirals get incorporated into nascent DNA leading to chain termination

Viral resistance

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

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Fig. 43-1. Mechanisms of action of nucleoside analogues used in the treatment of viral infections. Acyclovir and other nucleoside analogues are converted to active nucleoside triphosphates by viral and host cell kinases. These active nucleoside triphosphates compete with the corresponding endogenous nucleoside triphosphates and competitively inhibit viral DNA polymerase. Acyclovir and the nucleoside reverse transcriptase inhibitors (NRTIs) are incorporated into viral DNA and cause chain termination because they lack the 3'-hydroxyl group required to attach the next nucleoside. Ganciclovir and penciclovir do not cause chain termination.

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

(Thymidine kinase)

a. Nucleoside Analogsa. Nucleoside Analogs

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i. Acycloviri. Acyclovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: inhibit viral DNA polymerase by competition with nucleosidesincorporation and nascent DNA chain termination

Indications: treatment of HSV and VZV infectionsprophylactic for CMZ infectionstreatment of chickenpox (VZV) in children

Therapeutic Effects:for HSV: shortens healing time of lesions; reduces viral sheddingfor VZV: shortens acute pain; reduces severity of postherpetic neuralgia

Adverse effects:GI, headache, rash

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ii. Valacyclovirii. Valacyclovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: ester prodrug of acyclovir with better bioavailability (prodrug of a prodrug!)inhibit viral DNA polymerase by competition with nucleosidesincorporation and nascent DNA chain termination

Indications: treatment of HSV and VZV infectionsprophylactic for CMZ infections

Therapeutic Effects:for HSV: shortens healing time of lesions; reduces viral sheddingfor VZV: shortens acute pain; reduces severity of postherpetic neuralgia

Adverse effects:GI, headache, rash

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iii. Pencicloviriii. Penciclovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: inhibit viral DNA polymerase by competition with nucleosides

Indications: treatment of HSV in topical formulation

Therapeutic Effects:for HSV: shortens healing time of lesions; reduces viral shedding

Adverse effects:rash

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iv. Famcicloviriv. Famciclovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: ester prodrug of penciclovir with better bioavailability (prodrug of a prodrug)inhibit viral DNA polymerase by competition with nucleosides

Indications: treatment of HSV and VZV infections

Therapeutic Effects:for HSV: shortens healing time of lesions; reduces viral sheddingfor VZV: shortens acute pain; reduces severity of postherpetic neuralgia

Adverse effects:GI, headache, rash

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v. Ganciclovirv. Ganciclovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: inhibit viral DNA polymerase by competition with nucleosides

Indications: drug of choice for CMV infections: retinitis, pneumonia, colitis100X more active against CMV than acyclovir

Therapeutic Effects:treat or prevent cytomegalovirus (CMV) infectionsavailable in slow-release gel for intravitreous administration

Adverse effects:leukopenia and thrombocytopenia

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vi. Cidofovirvi. Cidofovir

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

a. Nucleoside Analogsa. Nucleoside Analogs

Mechanism of action: inhibit viral DNA polymerase by competition with nucleosides

Indications: i.v. only for CMV infections resistant to ganciclovir

Therapeutic Effects:treat or prevent cytomegalovirus (CMV) infections

Adverse effects:leukopenia and thrombocytopenia

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A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents a. Nucleoside Analogs

vii. TrifluridineMechanism of action:

irreversible inhibition of thymidylate synthetase inhibits viral DNA polymerase by competition with nucleosides

Indications: for HSV infections causing herpetic keratoconjunctivitis and epithelial keratitis

Therapeutic Effects:topical only formulation for treatment of ocular herpesvirus infections

Adverse effects:ocular irritation, redness, itching

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A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents b. Other agents

i. FoscarnetMechanism of action:

an inorganic pyrophosphate analogblocks pyrophosphate-binding sites on viral DNA polymerase preventing attachment of nucleotide precursorsonly non-nucleoside drug for treatment of herpesvirus

Indications: i.v. only for use in CMV and HSV infections resistant to first-line drugs

Therapeutic Effects:treatment of CMV and HSV infections in immunocompromised ptx

Adverse effects:nephrotoxicity, hypocalcemia (chelates divalent cations)

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Antiviral drug classificationAntiviral drug classification

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

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A. Non-Retroviral Antiviral Agents2. Anti-influenza Agents i. Amantadine

Mechanism of action: blocks M2 proton ion channel preventing acidification and fusion of virus

Indications: prevention and treatment of influenza A (only) infections

Therapeutic Effects:decrease in the severity and length of influenza A infections

Adverse effects:GI, and CNS effects including nervousness, insomnia, and anorexia

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A. Non-Retroviral Antiviral Agents2. Anti-influenza Agents ii. Rimantadine

Mechanism of action: blocks M2 proton ion channel preventing acidification and fusion of virusmore potent than amantadine

Indications: prevention and treatment of influenza A (only) infections

Therapeutic Effects:decrease in the severity and length of influenza A infections

Adverse effects:GI, and CNS effects including nervousness, insomnia, and anorexiaLess incidence of adverse effects than amantadine

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A. Non-Retroviral Antiviral Agents2. Anti-influenza Agents iii. Oseltamivir

Mechanism of action: inhibits neuroaminidases of both influenza A and B viruses preventing release of virions from infected cellsneuroaminidase inhibition also prevents spreading of virions in respiratory tract by leaving mucus intact

Indications: prevention and treatment of influenza A and B

Therapeutic Effects:decrease in the severity and length of influenza A and B infections

Adverse effects:minor GI complaints

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A. Non-Retroviral Antiviral Agents2. Anti-influenza Agents iv. Zanamivir

Mechanism of action: inhibits neuroaminidases of both influenza A and B viruses preventing release of virions from infected cellsneuroaminidase inhibition also prevents spreading of virions in respiratory tract by leaving mucus intact

Indications: prevention and treatment of influenza A and B

Therapeutic Effects:nasal spray only formulation; decreases in the severity and length of influenza A and B infections

Adverse effects:minor respiratory complaints

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Antiviral drug classificationAntiviral drug classification

A. Non-Retroviral Antiviral Agents1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

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A. Non-Retroviral Antiviral Agents3. Anti-hepatitis Agents a. Adefovir dipivoxil

Mechanism of action: ester prodrug of adefovir, a nucleotide analog of adenosineconverted to active diphosphate form which inhibits RT and vDNA polselectivity for HBV DNA polymerase over host cell polymerase

Indications: treatment of chronic hepatitis B (HBV) infections

Therapeutic Effects:reduces viral load of serum HBV by 100-foldnormalizes liver histology and enzymes by 48 weeks

Adverse effects:nephrotoxicity

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A. Non-Retroviral Antiviral Agents3. Anti-hepatitis Agents b. Lamivudine

Mechanism of action: nucleoside analog that inhibits both HIV RT and HBV DNA polymerasehost cell kinases convert to active triphosphate form

Indications: treatment of chronic hepatitis B (HBV) infections(also used in antiretroviral therapy)

Therapeutic Effects:reduces viral load of serum HBVnormalizes liver histology and enzymes

Adverse effects:mild: neutropenia, headache and nausea

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A. Non-Retroviral Antiviral Agents3. Anti-hepatitis Agents c. Ribavirin

Mechanism of action: nucleoside analog that inhibits viral replication of RNA and DNA viruseshost cell kinases convert to active monophosphate and triphosphate formmonophosphate: inhibits GTP synthesistriphosphate: inhibits 5’ capping of viral mRNA

Indications: treatment of chronic hepatitis C (HCV) infections (with pegIFN alfa-2)treatment of respiratory syncytial virus (RSV) in children in aerosoleffective in wide variety of other viruses

Therapeutic Effects:reduces viral load of serum HBCnormalizes liver enzymes

Adverse effects:oral: reversible anemia; aerosol: rash, wheezing, decreased lung function

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A. Non-Retroviral Antiviral Agents3. Anti-hepatitis Agents d. Interferons (pegIFN alfa 2a, 2b)

Mechanism of action: antiviral, anticancer and immunomodulating endogenous chemokines several sites of action in viral cycle; inhibit translation of viral proteins inhibits both hepatitis B and C virusesIndications:

treatment of chronic HBV and HCV infectionstreatment of condylomata acuminata (genital warts) due to HPV(also for Kaposi’s sarcoma in HIV ptx; malignancies, and multiple sclerosis)

Therapeutic Effects:in combination with ribavarin, reduces viral load of serum HBV and HCVintralesion injections for genital warts effective in 50% of ptx

Adverse effects:flu-like syndrome, bone marrow suppression; CNS

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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HIV phylogeneticsHIV phylogenetics

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Retrovirus reverse transcription – HIV lifecycle

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Targeting HIV replication

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Fig. 43-2. Sites of action of drugs for human immunodeficiency virus (HIV) infection. Enfuvirtide inhibits the fusion of HIV with host CD4 cell membranes. After the virus penetrates the host cell and becomes uncoated, the viral RNA is transcribed by reverse transcriptase to form viral DNA. Viral DNA is incorporated into the host genome in the cell nucleus by HIV integrase. The viral DNA is then transcribed to RNA. Viral RNA is incorporated into new virions and is translated to synthesize polyproteins. The polyproteins are cleaved into viral proteins by HIV protease as the new virions are released from the cell.

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

a. Zidovudine (azidothymidine:AZT)

Mechanism of action: nucleoside analog activated to triphosphate form by host cell kinases inhibits HIV RT function incorporation by HIV RT into proviral DNA causes chain terminationIndications:

treatment of HIV infectionsprevention of maternal to infant HIV transmission

Therapeutic Effects:in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:granulocytopenia and anemia; headache, nausea, insomnia, myalgias

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

b. Lamivudine

Mechanism of action: nucleoside analog that inhibits both HIV RT and HBV DNA polymerasehost cell kinases convert to active triphosphate form

Indications: treatment of HIV infections in combination with other antiretroviral agents(also used in treatment of chronic hepatitis B (HBV) infections)

Therapeutic Effects:in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells

Adverse effects:mild: neutropenia, headache and nausea

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

c. Stavudine and d. Didanosine

Mechanism of action: nucleoside analogs activated to triphosphate form by host cell kinases inhibits HIV RT function incorporation by HIV RT into proviral DNA causes chain terminationIndications:

treatment of HIV infectionsTherapeutic Effects:

usually not first-line treatmentin combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:peripheral neuropathy; HIV lipodystrophy syndrome (fat wasting)didanosine also pancreatitis

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

e. Abacavir

Mechanism of action: nucleoside analogs activated to triphosphate form by host cell kinases inhibits HIV RT function incorporation by HIV RT into proviral DNA causes chain terminationIndications:

treatment of HIV infectionsTherapeutic Effects:

usually not first-line treatmentin combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:hypersenstivity rx; repeat exposure often fatal

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

f. Emtricitabine

Mechanism of action: nucleoside analogs activated to triphosphate form by host cell kinases inhibits HIV RT function incorporation by HIV RT into proviral DNA causes chain termination antiviral activity 10-fold greater than lamivudineIndications:

treatment of HIV infections in combinations with other agentsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:mild; pigmentation of skin

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B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)

g. Tenofovir

Mechanism of action: nucleoside analogs activated to triphosphate form by host cell kinases inhibits HIV RT function incorporation by HIV RT into proviral DNA causes chain terminationIndications:

treatment of HIV infections in combinations with other agentsTherapeutic Effects:

usually not first-line treatmentin combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:mild; flatulence

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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B. Antiretroviral Agents 2. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI)

a. Nevirapine

Mechanism of action: non-competitively binds to allosteric site on HIV RT enzyme causes conformational change which inhibits HIV RT function no host cell activation required as in NRTIsIndications:

treatment of HIV infectionsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:rash; Stevens-Johnson syndrome rarely

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B. Antiretroviral Agents 2. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTI)

b. Efavirenz

Mechanism of action: non-competitively binds to allosteric site on HIV RT enzyme causes conformational change which inhibits HIV RT function no host cell activation required as in NRTIsIndications:

treatment of HIV infectionsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:CNS: dizziness, insomnia, impaired concentration, psychotic episodes

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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The translational products of the HIV gag–pol gene and the sites at which the gene product is cleaved by the virus-encoded protease. p17 denotes capsid protein, p24 matrix protein, and p7 nucleocapsid; p2, p1, and p6 are small proteins with unknown functions. The arrows denote cleavage events catalyzed by the HIV-specific protease.

Protease InhibitorsProtease Inhibitors

Protease action

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B. Antiretroviral Agents 3. Protease Inhibitors (PI)

a. Saquinavir

Mechanism of action: first approved peptide-like agent that inhibits HIV protease selective for homodimer of HIV protease; homolog in host are monomer

blocks cleavage of gag-pol precursor proteins and prevents maturationIndications:

treatment of HIV infectionsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:GI including N/V, diarrhea, anorexia and taste perversionHIV lipodystrophy syndrome

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B. Antiretroviral Agents 3. Protease Inhibitors (PI)

b. Atazanivir

Mechanism of action: peptide-like agent that inhibits HIV protease selective for homodimer of HIV protease; homolog in host are monomer

blocks cleavage of gag-pol precursor proteins and prevents maturationIndications:

treatment of HIV infectionsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:hyperbilirubinemia not associated with other hepatotoxicityless likely to cause HIV lipodystrophy syndrome

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B. Antiretroviral Agents 3. Protease Inhibitors (PI)

c. Ritonavir

Mechanism of action: peptide-like agent that inhibits HIV protease selective for homodimer of HIV protease; homolog in host are monomer

blocks cleavage of gag-pol precursor proteins and prevents maturationIndications:

treatment of HIV infections most potent inhibitor of CYP3A4 so used in boosted therapy with other PITherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:GI including N/V, diarrhea, anorexia and taste perversionHIV lipodystrophy syndrome

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B. Antiretroviral Agents 3. Protease Inhibitors (PI)

d. Lopinavir

Mechanism of action: peptide-like agent that inhibits HIV protease selective for homodimer of HIV protease; protease in host cell is monomer

blocks cleavage of gag-pol precursor proteins and prevents maturation similar to Ritonavir but 10-fold more potentIndications:

treatment of HIV infectionsTherapeutic Effects:

in combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:GI including N/V, diarrhea, anorexia and taste perversionHIV lipodystrophy syndrome

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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B. Antiretroviral Agents 4. Entry Inhibitors

a. Enfuvirtide

Mechanism of action: large peptide that binds to HIV gp 41 and blocks fusion i.v. route of administrationIndications:

treatment of HIV infections in combination with other antiretroviral drugsTherapeutic Effects:

usually not first-line treatment, used when other drugs ineffectivein combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:injection site irritation

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B. Antiretroviral Agents 4. Entry Inhibitors

b. Maraviroc

Mechanism of action: antagonist of CCR5 co-receptor on CD4 cells prevents binding of HIV glycoproetin 120 (gp120) to CCR5 co-receptor inhibits CCR5-tropic HIV entry (HIV can also use CXCR4 co-receptor)Indications:

treatment of HIV infections in combination with other antiretroviral drugsTherapeutic Effects:

usually not first-line treatmentin combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells↓mortality and opportunistic infections, gain weight, better quality of life, delays signs and symptoms of AIDS

Adverse effects:Hepatotoxicity; may be preceded by systemic allergic reaction

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Antiviral drug classificationAntiviral drug classificationA. Non-Retroviral Antiviral Agents

1. Anti-herpesvirus Agents2. Anti-influenza Agents3. Anti-hepatitis Agents

B. Antiretroviral Agents1. Nucleoside Reverse Transcriptase Inhibitors (NRTI)2. Non-nucleoside Reverse Transcriptase Inhibitors (NNRTI)3. Protease Inhibitors (PI)4. Entry Inhibitors5. Integrase Strand Transfer Inhibitors

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B. Antiretroviral Agents 5. Integrase Strand Transfer Inhibitors a. Raltegravir

Mechanism of action: recruits divalent cation binding to core area of HIV integrase prevents HIV integrase from integrating viral DNA into host DNA Indications:

treatment of HIV infectionsTherapeutic Effects:

usually not first-line treatmentin combination with other antiretroviral drugs, reduces viral load of HIV and increases CD4 cells

Adverse effects:headache, GI and N/V

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HIV drug resistance

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Antiviral vaccinesAntiviral vaccinesMeaslesMumpsRubellaPolioHepatitis A and BHerpes zosterHuman papillomavirus Influenza A and BRotavirusRabiesMonkeypoxSmallpoxJapanese encephalitisYellow fever

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