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Pharmacology Drugs > Antivirals > Flashcards

Antivirals Flashcards

1
Q

Which Drugs can be used to treat Herpes?

A
  • Aciclovir
  • Ganciclovir
  • Cidofovir
  • Foscarnet
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2
Q

What is the mechanism of action of Aciclovir?

A
  • Phosphorylated by thymidine kinase
  • Then phosphorylated twice by the cells to form active aciclovir triphosphate
  • Competes with dGTP as a substrate for viral DNA polymerase as well as acting as a chain terminator
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3
Q

What are the side effects of Aciclovir?

A
  • Some nephrotoxicity
  • CNS symptoms (lethargy, confusion, tremor, myoclonus, hallucinations, delirium, seizures, autonomic symptoms, coma, extrapyramidal signs)
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4
Q

What is the mechanism of resistance of aciclovir?

A

Resistance arises via:

  • Absent/reduced TK enzyme
  • Altered TK substrate target
  • Altered DNA polymerase
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5
Q

What is used to treat Influenza A & B drugs gained?

A
  • Oseltamavir (orally)

- Zanamivir (inhaler/intranasal)

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6
Q

What is the mechanism of action of influenza A & B drugs gained?

A

Neuraminidase inhibitor - blocks release of newly assembled influenza virions from the host cell

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7
Q

How is resistance against influenza A & B drugs gained?

A

Mutation of Neuraminidase enzyme (often less infective: “less fit virus”)

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8
Q

What are examples of use of oseltamivir and zanamivir?

A

Can be used prophylactically to prevent infection or within 48 hours of infection to reduce intensity and duration of symptoms. Yearly vaccinations for those at risk

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9
Q

When is Aciclovir used?

A

Aciclovir only effective during acute phase of viral infection where patient is symptomatic. Not during latent phase. Wont prevent new outbreak, only help to control time/severity of outbreak.

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10
Q

What is ganciclovir used for?

A

Currently used for CMV retinitis in immunocompromised and CMV prophylaxis in
transplant patients.

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11
Q

What is the mechanism of action of Ganciclovir?

A

Analogue of acyclovir (10-50 times greater activity against CMV) acts in same way but is phosphorylated using different enzyme - not thymidine kinase

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12
Q

What are ADRs of ganciclovir?

A
  • Myelosupressive (severe dose dependent neutropenia)
  • Carcinogenic/teratogenic
  • Renally cleared so accumulates in renal failure.
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13
Q

What is Lamivudine used to treat?

A
  • HIV

- Hep B

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14
Q

How does Lamivudine work?

A

Reverse transcriptase inhibitor

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15
Q

How does SOFOSBUVIR work?

A

Blocks action of HCV viral polymerase to prevent production of new virus

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16
Q

What is Interferon Alpha used for?

A

-Used mainly in the treatment of Hep B/C

17
Q

What is the mechanism of action of Interferon Alpha?

A

-Immunomodulatory effect

18
Q

What are adverse effects of Interferon Alpha?

A
  • Flu-like illness
  • Fever, chills
  • Headache
  • Malaise
  • Myalgia
  • Arthralgia
  • Nausea
  • Vomiting
  • Diarrhoea
19
Q

What is the Ribavirin used for?

A

-Used in treatment of chronic hepatitis C (in combination with interferon alpha) and treatment of infants with severe RSV infection

20
Q

What is the mechanism of action of Ribavirin?

A

-Guanosine analogue: inhibits guanosine triphosphate formation preventing viral messenger RNA capping. Essentially prevents assembly of viral genome/DNA

21
Q

What are ADRs of Ribavirin?

A
  • Transient anaemia

- Teratogenic

22
Q

How is HIV treated?

A

2 NRTIs and 1 of:

  • NNRTI
  • Protease inhibitors
  • Integrase inhibitors
  • Fusion inhibitors
23
Q

What is the mechanism of action of HIV Drugs?

A

NRTI: Inhibit DNA polymerase

NNRTI: Active without further phosphorylation. Non-competitive inhibitors of HIV reverse transcriptase – bind at different sites to the
NRTI but have same effect = therefore can be used as combination therapy. Only work on HIV-1 not HIV-2

Protese inhibitor: Block the cleavage of viral polyproteins by HIV protease enzyme, preventing the production of viral proteins for the formation
of final mature virions

Intergrase Inhibitors: Prevent integration of HIV DNA provirus into host cell genome

24
Q

Why is antiviral drug resistance testing needed?

A
  • To optimise the clinical outcomes, quality of life, longevity of the patient
  • To save costs and adverse effects of ineffective therapy
  • To reduce the pool of drug resistant viruses in the population that may transmit between individuals, reducing the effectiveness of standard therapy
25
Q

When is antiviral drug resistance testing used?

A

-Evidence of therapeutic failure: could be due to resistance, poor compliance, as baseline prior to starting new medication

26
Q

How is antiviral drug resistance testing done?

A
  • Incubate suspected drug resistant virus with varying concentrations of the drug of interest in a culture
  • Look for graded response compared to a wild-type virus, e.g. enzyme-activity changes, PRNT
  • Can then look at specific sequencing/genotype of the mutation

Pharmacology Drugs (22 decks)

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