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Flashcards in Antivirals Deck (58):
1

Tx of respiratory viral infections

neuraminidase inhibitors
inhibitors of viral uncoating
synthetic guanosine analog

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oseltamivir

neuraminidase inhib

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zanamivir

neuraminidase inhib

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amantadine

inhibts viral uncoating

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rimantadine

inhibitors of viral uncoating

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ribavirin

synthetic guanosine analog

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neuraminidase inhibitors

oseltamivir, zanamivir

work against type A and B influenza - prophylaxis OR after onset of sxs

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neuraminidase inhib MOA

neuraminidase cleaves hemaglutinin residues from surface receptors - allows cleavage and budding of virus

--> INHIBITION of virion release d/t halted viral replication

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olsetamivir vs zanamivir

olsetamivir: ORAL - hydrolyzed in liver

zanamivir: INHALE or INTRANASAL - less bioavail`

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zanamivir AE

airway irritation - avoid in pt with asthma and COPD

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Ion channel blockers

amantadine, rimantadine

only active on influenza type A
- not recommended as first line tx anymore b/c resistance

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ion channel blocker MOA

blocks viral membrane protein - M2 (H+ channel)
- channel needed for fusion of viral with cell membrane to endosome

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amantadine vs rimantadatine? which crosses BBB

amantadine = crosses BBB
- excreted in urine

greater AE with amantadine

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ion channel blockers contraindications

pregnancy
nursing

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ribavarin use

active against RNA/DNA viruses - broad spec
used in combo with IFN-alpha or HCV tx

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ribavarin MOA

convert to ribavirin - triphosphate = inhibits GTP formation - no viral mRNA capping

inhib RNA dep RNA polym = inhib of protein synthesiss

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ribavarin AE

dose dependent transient anemia
GI
CNS

PREGNANCY X - teratogen, can also affect those nearby, doesn't need to be ingested by only 1 person

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hepatic viral infection tx

1) IFN-alpha
2) nucleotide analog
3) protease inhibitors

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ifn alpha

glycoproteins/cytokines - alpha and beta produced by many cell types

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IFN-a MOA

naturally occuring
an be peglyated

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nucleoside analogs

lamiduvidne
entecavir

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lamidvudine

protect against hep B and HIV - in triphosphate form

monophosph form = incorporated into DNA (via HBV polymerase) -- chain termination

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entecarvir use

effective against lamivudine resistant HBV and HIV strains

phosphorylated form = competes for viral polymerase - inhibitiors blocks reverse transcriptase

STOPS ASSEMBLY and maturation

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entecavir AE

monitor after discontinuation for severe hepatitis exacerbation

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Protease inhibitors

boceprevir
telaprevir

tx HCV in pt previously failed tx with IFN-a and ribavarin
- given in combo with IFN-a and ribavrin

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boceprevir

protease inhib

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telaprevir

protease inhib

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protease inhib MOA

binds reversibly to nonstructural protein 3 - serine protease and inhibts replication of HCV

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protease inhib AE

fatigue
anemia
nausea
dysgeusia

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Herpes Tx

purine/pyrimidine analogs
foscarnet

inhibition of RNA and DNA synthesis

31

Acyclovir

active against HSV1 and 2, VZV, HSV4

prophylactic in immunocompromised transplant pt

CMV is resistant (Doesn't encode thymidine kinase)

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DOC in HSV encephalitis

acyclovir

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prodrug of acyclovir

valacyclovir

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acyclovir MOA

3 phosphorylation steps

monophosph by herpes virus encoded thymidine kinase

host completes phosphorylation to di and triphosph

competes with dGTP = once incorporation -- chain terminates - inhib of viral DNA polym

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acyclovir resistance

no cross resistance

1) deficient thymdine kinases
2) altered viral DNA pol - dec affinity for acyclovir

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which has greater oral bioavailbility, ayclovir or valacyclovir

valacyclovir

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acyclovir AE

topical admin = irritation locally

oral = HA, n/v/d

IV: renal failure - minimize with slow infusion and prior hydration

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DOC for CMV retinitis and prophylaxis

ganciclovir

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ganciclovir

prodrug - valganciclovir (greater oral bioavail)

aycclovir analog - but has more acitivity against CMV

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ganciclovir MOA

phosphorylated by viral (UL97) and cell kinases

DNA chain terminator and DAN pol inhib

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ganciclovir resistance

dec intracellular phosphorylation

mutations to phosphotransferase

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ganciclovir excretion

urine

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ganciclovir AE

myelosuppresion
dose dependent neutropenia

CONTRAINDIC in PREGNANCY

44

cidofovir

CMV induced retinitis in HIV/AIDS

NOT phoshporylated by viral kinases

requires activ by host cell kinases

active against HSV and ganciclovir resis HSV

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cidofovir MOA

DNA chain terminator and DNA pol inhib

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cidofovoir resistance

viral DNA pol mutations

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cidofovir AE

nephrotoxicity

48

penciclovir

HSV1, 2 and VZV use

topical tx of HSV (cold sores)

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penciclovir MOA

monophosphorylated by viral thymidine kinase

further phosph --> triphosphate form

Inhibits HSV DNA pol/chain temrinator

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penciclovir AE

mild erythema

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Trifluridine

active against HSV 1 and 2, vaccina virus

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DOC HSV keratoconjunctivitis and reccurent epithelial keratitis

trifluridine

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trifluridine MOA

triphosph form incorportated into viral DNA = fragmentation

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trifluridine PK

short t 1/2 - reapply frequently

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foscarnet

analog of inorganic pyrophosphate

NO phosphorylation required

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Tx
- CMV retinitis in immunocompromised
- aycylovir resistant HSV
- CMV retinitis
- ganciclovir resistant CMV and VZV

foscarnet

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foscarnet MOA

analog of anion pyrophosphate - selectively inhibits pyrophosphate binding site on viral DNA pol

58

foscarnet AE

nephrotoxicity
electrolyte disturbances: Ca, Mg, K, PO4
CNS - hallucinations, seizures, HA