antiviral agents gold

8/8/2019 Antiviral Agents Gold

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ANTIVIRAL

AGENTS


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Viruses cause variety ofconditions

Warts , common cold, flu

Chicken pox, measles

Composed of DNA & RNA inside

protein coat.


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Replication cycle of a virus

a) Attachment

b) Penetration

c) replication


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Replication cycle of a virus

d) synthesis

e) assembly

f) release


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Viruses are contained inside human

cells difficult to develop effective drugs

that destroy a virus w/o harming

human host Interferons- released in response to

viral invasion, prevent replication


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Influenza A and respiratory

viruses

Include influenza B, respiratory

syncytial virus (RSV), invade respi

tract and cause symptom of flu


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Rimantadine prototype

Prophylaxis and txt of illness cause by

influenza A virus in adults Prophylaxis in children


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Drug-drug interactions

w/ antcholinergic drugs increase atropine

like effects


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Herpes & CMV

Herpes cold sores, encephalitis,

shingles, genital infections

CMV slightly different Affect eyes, respi tract, liver


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Therapeutic actions

Inhibit viral DNA replications by

competing with viral substrates to form

shorter, non effective DNA chains. Prevent replication of virus

Little effect on the host cells of human

cause their DNA uses different substrates


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Effective in immunocompromisedindividual (AIDS, multiple infection)


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Acyclovir

prototype

Herpes simplex virus 1 & 2 infections,

severe genital HSV infections,encephalitis, acute treatment

shingles,chicken pox

Ointment for genital herpes

Cream cold sores (herpes labialis)


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Drug-drug interactions

Risk nephrotoxicity when in combination

w/ nephrotoxic drugs


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Agents for hiv & aids

HIV attacks helper T cells w/in immune

system

Multiply w/in the cell When cell rupture, many new viruses are

released to attack other helper T cells

Loss of Immune reaction


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Lost T cell function AIDS or AIDSrelated complex (ARC)

Characterized by opportunistic

infections and Ca HIV mutates over time


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2 reasons difficult

treatment of AIDS/ ARC:1. Length of time the virus can remain

dormant w/in T cell

2. Adverse effects of drugs (depressimmune system)


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Agents treat HIV infection

Reverse trancriptase inhibitors

Protease inhibitors

Nucleosides

Fusion inhibitors


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Reverse transcriptase inhibitors

Binds directly to HIV reverse

transcriptase, blocking both RNA & DNA

dependent DNA polymerase activities Prevent transfer of information that

would allow the virus to replicate and

survive


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Blocks protease activity w/in HIV

virus Protease essential for maturation

of an infectious virus, w/o it, HIV

particle is immature andnoninfective.

Protease inhibitors


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prototype

Indinavir (Crixivan)

Txt of adults & children older 12 y.o w/

HIV Rapidly absorbed GIT, metabolize liver,

excreted urine


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nucleosides

Interfere w/ HIV replication by

inhibiting cell protein synthesis

leading viral death


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prototype

Zidovudine

Mgt of adults w/ symptomatic HIV

infections in combination w/ otherantiretrovirals

Prevention of maternal-fetal HIV

transmission.


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Fusion inhibitors

New class

Introduced 2003

Prevents fusion of virus w/ the humancellular membrane, w/c PreventsHIV-1

virus fro entering the cell.


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Therapeutic actions

treat HIV & AIDS operate @ various

points in life cycle of virus

result in its death & inactivation Use in combination

Txt AIDs or ARC who have decreased no T

cells & evidenced of increased

opportunistic infections


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Enfuvirtide (Fuzeon)

In combination w/ antiretroviral agents

to treat adults and children older 6 y.o.,

w/ evidenced ofHIV-1 replication despiteongoing therapy.

SQ; peak 4-8 hours


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Half-life : 3.2 4.4 hours

Asso. w/ insomnia, depression,

peripheral neuropathy, nausea, diarrhea,pneumonia, injection site reactions


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Locally active

antiviral agents Table 10.4

Prototype : Idoxuridine (Herplex)

applied directly to eye & is used to treatherplex simplex keratitis


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actions

Interfere with normal viral replication

and metabolic processes.

Indicated for specific local viral infections

antiviral agents gold

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