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MHD2/Pharm Block 5 > Antiviral drugs > Flashcards

Antiviral drugs Flashcards

1
Q

Docosanol/”Abreva”

A

Over the counter cold sore medication (anti-herpes)
Blocks virus entry
Reduces healing time by ~1 day

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2
Q

What is valtrex?

A

Val-acyclovir and Val-gangcyclovir
Val is added to improve bioavailability
Cleavage by esterases results in active drug formation

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3
Q

How does acyclovir act selectively on herpes infected cells?

A

Acyclovir is activated by a herpes thymidine kinase enzyme in the cytoplasm of infected cells
It also requires herpes DNA polymerase to insert into replicating DNA and cause chain termination

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4
Q

What class of drugs do acyclovir and gancyclovir interact with?

A

Antibiotics

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5
Q

How does the specitrum of activity of gancyclovir differ from acyclovir?

A

Gancyclovir treats CMV, HHV6 and 8 as well as EBV

Acyclovir treats HSV

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6
Q

What adverse effects are associated with gancyclovir

A

Bone marrow suppression
Rash, diarrhea, nausea, vomiting
Rarely, neurotoxicity

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7
Q

What is foscarnet?

A

An analog of pyrophosphate that inhibits pyrophosphate binding on viral DNA polymerase
Foscarnet has broad coverage of the herpes viruses
Useful for resistance to acyclovir/gancyclovir

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8
Q

What adverse effect is associated with foscarnet?

A

Nephrotoxicity due to accumulation of foscarnet crystals in the glomeruli
Electrolyte disturbances
Myelosuppresion & anemia

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9
Q

What is the mechanism of action of pritelivir?

A

Anti-HSV medication that inhibits helicase-primase to block viral DNA replication

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10
Q

What class of drugs is used to treat HCV?

A

Directing-acting antivirals (DAAs) to competitively inhibit viral protease (NS3/4), viral phosphoprotein (NS5A) and viral RNA polymerase (NS5B)

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11
Q

What is the mechanism of action of Ribavirin?

A

Deplete GTP pools, directly block viral RNA polymerase and induce catastrophic errors during viral replication, trigger antiviral T cell responses

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12
Q

What infections are treated with Ribavirin?

A

HCV

RSV

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13
Q

Ribavirin should be used in combination with what?

A

Ribavirin is used in conjunction with pegylated IFN

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14
Q

What is the mechanism of action of PegIFN?

A

Stimulates host antiviral immunity

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15
Q

Adverse effects of PegIFN

A

Severe flu-like symptoms
Depression
Caution with cirrhosis patients

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16
Q

What is the difference in recommendation for HBV therapy between HBeAg- and HBeAg+ infecitions

A

HBeAg- is less infectious, so only treated if viral load is higher (>10^5) compared to HBeAg+, which is treated at lower levels (>10^4)

17
Q

What drugs are available for pharmacologic management of HBV?

A

PegIFN
Entecavir - guanosine analog
Tenofovir - adenosine analog

18
Q

What is the mechanism of action of entecavir?

A

Inhibits HBV DNA priming, reverse transcriptase and DNA polymerase

19
Q

Adverse effects of entecavir

A

Lactic acidosis

Rebound hepatitis

20
Q

Drug interactions with entecavir

A

Don’t use in conjunction with HAART for HIV

21
Q

What drug is used to treat HBV and HIV? How does it work?

A

Tenofovir

Converted to nucleoside analog which gets phosphorylated and blocks viral DNA polymerase

22
Q

Drug interactions of tenofovir can cause what problems

A

renal toxicity

lactic acidosis

23
Q

Mechanism of action of amantadine

A

Inhibits influenza A virus entry by plugging the M2 ion channel, thus preventing protons from entering the virus

RNA will not release from virion proteins and uncoating is prevented

24
Q

What is the main problem with amantadine/rimantadine?

A

Drug resistance has limited clinical utility

25
Q

What are the neuraminidase inhibitor drugs?

A

Zanamivir (aerosol inhalant)

Oseltamivir (oral)

26
Q

What is the mechanism of action of neuraminidase inhibitors?

A

Selective inhibition of virus release from infection sites

27
Q

Clinical use for oseltamivir & zanamivir

A

Postexposure prophylaxis (within 2 days of exposure) can shorten disease duration by 1-2 days and limit peak symptoms

28
Q

How is RSV treated?

A

Palivizumab: RSV Ig = passive immunotherapy

Ribavirin

29
Q

Why is monotherapy often not used for viral infections?

A

Suboptimal dosing can lead to resistance

30
Q

Describe the concept of “Low barrier to drug resistance”

A

Single residue mutations can result in drug resistance

Ex: Amantidine rendered useless by a point mutation in the gene encoding the M2 protein

MHD2/Pharm Block 5 (5 decks)

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