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(LUSUMA) Clinical Pharmacology & Therapeutics > S9) Antiviral Agents > Flashcards

S9) Antiviral Agents Flashcards

1
Q

Identify and describe four agents which directly inactivate viruses (virucides)

A
  • Non-organic (detergents, chlorine-based agents)
  • Organic solvents e.g. ether, alcohol, chloroform
  • Radiation e.g. UV light, laser therapy for warts
  • Cryotherapy e.g. for warts removes lesions but may not inactivate virus itself
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2
Q

What is the limitation of virucides?

A

These agents cannot be used systemically, and only in specific situations topically

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3
Q

What are the six steps in viral replication?

A

⇒ Attachment

⇒ Uncoating

⇒ RNA/DNA replication

⇒ Protein synthesis

⇒ Assembly

⇒ Release

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4
Q

Identify some agents which inhibit viral replication

A
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5
Q

What are the limitations of agents that inhibit viral replication?

A
  • Interference with host-cell metabolism can result in adverse effects
  • Ineffective against non-replicating/latent viral infections
  • May exhibit rebound effects when drug is stopped
  • Possible development of drug resistance
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6
Q

What do immunomodulators of host response to viral infection do?

A
  • Replace deficient host immunity e.g. immunoglobulins for HBV, VZV
  • Enhance host immunity e.g. interferons, Imiquimod
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7
Q

What are immunoglobulins?

A

Immunoglobulins are pooled human sera from blood donors, containing preformed antibodies (IM/ SC/ IV injection)

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8
Q

Identify five immunoglobulins and the conditions they are used to treat

A
  • HBIG – HBV
  • VZIG – VZV
  • HRIG – Rabies
  • VIG – Vaccinia
  • HNIG – HAV, measles, polio rubella
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9
Q

What are the different groups of anti-herpes drugs?

A
  • Aciclovir
  • Ganciclovir
  • Cidofovir
  • Foscarnet
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10
Q

Aciclovir is an anti-herpes virus drug.

How does antiviral resistance arise?

A

Resistance arises via absent/ reduced TK enzyme, or altered TK substrate target, or altered DNA polymerase

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11
Q

What are some adverse drug reactions of aciclovir?

A
  • Lethargy
  • Confusion
  • Tremor
  • Hallucinations
  • Myoclonus
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12
Q

In four steps, explain how aciclovir acts to inhibit viral DNA polymerase

A

⇒ Aciclovir molecules enter the cell

⇒ HSV enzyme TK converts it to aciclovir monophosphate

⇒ Human enzymes add 2 more phosphates to form the active drug acyclovir triphosphate

⇒ Aciclovir triphosphate competes with dGTP as a substrate for viral DNA polymerase + acts as a chain terminator

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13
Q

What are the different groups of anti-hepatitis drugs?

A
  • Lamivudine
  • Adefovir
  • Emtricitabine
  • Entecavir
  • Ribavirin
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14
Q

How do lamivudine and adefovir act?

A

Both act as false substrate and chain terminator of reverse transcriptase (RT) enzyme in HIV and HBV replication

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15
Q

What are interferons?

A
  • Interferons are naturally produced substances by the body’s non-specific innate immune system
  • They are potent cytokines – immunomodulating, antiproliferative
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16
Q

Which viruses are interferons used to treat?

A
  • HBV
  • HCV
17
Q

Oseltamivir is an anti-influenza drug.

What is its mechanism of action?

A

Reversible inhibitors of viral neuraminidase enzyme that cleaves sialic-acid receptor-HA bond between host cell and virus

18
Q

How does antiviral resistance to osetamivir arise?

A

Resistance arises due to mutations in NA gene (H274Y/ H275Y), producing a less fit virus.

19
Q

Oseltamivir is generally well tolerated.

Regardless, what are some of its adverse effects?

A
  • Nausea
  • Vomiting
  • Abdominal discomfort
  • Rashes
  • Headaches
20
Q

Identify five different groups of anti retroviral (HIV) drugs

A
  • Nucleoside reverse transcriptase inhibitors (NRTIs)
  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
  • Protease inhibitors (PIs)
  • Fusion inhibitors (FIs)
  • Integrase inhibitors (INIs)
21
Q

Provide three examples of NRTIs

A
  • Zidovudine (AZT)
  • Didanosine (ddI)
  • Lamivudine
22
Q

Describe the mechanism of action of NRTIs

A

- NRTIs act as false substrates and lack the 3’-OH group for DNA elongation, so when incorporated, will terminate production of the HIV DNA provirus

  • Also, Inhibit the DNA polymerase function of the HIV RT enzyme
23
Q

Identify some ADRs of NRTIs

A
  • Lactic acidosis
  • Hepatomegaly
  • Steatosis
  • Hyperlactaemia
24
Q

Describe the mechanism of action for NNRTIs

A

NNRTIs are non-competitive inhibitors of HIV RT by allosteric inhibition of enzyme function, binding at different sites from the NRTI sites

25
Q

Identify some ADRs of NNRTIs

A
  • Erythematous maculopapular rash
  • Raised LFTs
  • CNS symptoms

(LUSUMA) Clinical Pharmacology & Therapeutics (29 decks)

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