Page 280 - Review of Medical Microbiology and Immunology ( PDFDrive )

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P
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Antiviral Drugs

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CHAPTER C ONTENT S

Inhibitors of Human Immunodeficiency Virus
Principles of Antiviral Therapy
Inhibition of Early Events
Inhibitors of Hepatitis C Virus
Inhibition of Viral Nucleic Acid Synthesis
Inhibitors of Herpesviruses
Interferon
Fomivirsen
Inhibitors of Retroviruses
Inhibitors of Hepatitis B Virus
Inhibitors of Hepatitis C Virus Inhibition of Release of Virus
Chemoprophylaxis
Pearls
Inhibitors of Other Viruses
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Self-Assessment Questions
Inhibition of Integrase
Practice Questions: USMLE & Course Examinations
Inhibition of Cleavage of Precursor Polypeptides
(Protease Inhibitors)

PRINCIPLES OF ANTIVIRAL
THERAPY
herpesviruses) become latent within cells, and no current
antiviral drug can eradicate them.
Compared with the number of drugs available to treat
bacterial infections, the number of antiviral drugs is very it is too late to interdict it. Furthermore, some viruses (e.g.,
Another limiting factor is the emergence of drug-resistant
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small. The major reason for this difference is the diffi-
viral mutants. For example, when drug-resistant mutants of
culty in obtaining selective toxicity against viruses;
HIV emerge, it requires that drug regimens be changed.
their replication is intimately involved with the normal
Also, treatment of HIV infection uses multiple drugs, often
synthetic processes of the cell. Despite the difficulty, sev-
drug emerge, another drug will still be effective.
eral virus-specific replication steps have been identified
that are the site of action of effective antiviral drugs
(Table 35–1). Table 35–2 describes the mode of action of
antiviral drugs that block early events in viral replication,
INHIBITION OF EARLY EVENTS
and Table 35–3 describes the mode of action of antiviral
drugs that block viral nucleic acid synthesis. Figure 35–1
shows the replication of a model virus and the site of action
three-ring compound (Figure 35–3) that blocks the rep-
of drugs used to treat various viral infections. Figure 35–2
lication of influenza A virus. It prevents replication by
shows the replication of human immunodeficiency virus Amantadine (α-adamantanamine, Symmetrel) is a
inhibiting uncoating of the virus by blocking the “ion
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channel” activity of the matrix protein (M2 protein) in
(HIV) and the site of action of drugs used to treat HIV
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the virion. Absorption and penetration occur normally,
infection.
Another limitation of antiviral drugs is that they are
but transcription by the virion RNA polymerase does
relatively ineffective because many cycles of viral replica-
cally inhibits influenza A virus; influenza B and C viruses
tion occur during the incubation period when the patient
is well. By the time the patient has a recognizable systemic
are not affected.
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