Antiviral medications Flashcards
what is the adult and child dose for oseltamivir?
what is the dose for prophylaxis?
adult dose 75mg BID for 5 days
child dose 30-75mg BID for 5 days
prophylaxis 75mg OD for 10 days
oseltamivir and zanamivir belong to which class
neuraminidase inhibitors
what is the MOA of oseltamivir and zanamivir
Oseltamivir and Zanamivir inhibit neuraminidase and virions accumulate at the internal infected cell surface without release
neuraminidase inhibitors are effective against ifluenza A, B and C. t/f
false. only infleunza A and B
oseltamivir and zanamivir are taken orally. t/f
false. oseltamivir is taken orally, zanamivir is inhaled or taken intranasally
zanamivir should be avoided in patients with _________.
COPD and asthma
what is the adverse effect associated with oseltamivir
GIT discomfort
name the drugs which act by inhibiting viral uncoating
amantadine and rimantadine
what is the MOA of amantadine/rimantadine
These drugs block the viral membrane matrix protein M2 which is required for fusion of the viral membrane with the cell membrane to form the endosome.
They also interfere with the release of new virions.
amantadine/rimantadine are effective only against ________.
infleunza A virus
amantadine/rimantadine arnot effective against vaccines why?
used to supplement vaccinations
which drug crosses the BBB
a. amantadine
b. rimantadine
a. amantadine
amantadine is teratogenic but rimantadine is not. t/f
false. both are teratogenic
amantadine causes CNS problems whereas rimantadine does not. t/f
true because rimantadine does not cross the BBB
both amantadine/rimantadine cause GI problems. t/f
true
what are the therapeutic indiations of ribavirin
Effective against many RNA and DNA viruses
Used in severe respiratory syncytial virus bronchiolitis in infants and children
Used in combination with interferon for chronic hepatitis C
MOA of ribavirin
Ribavirin prevents mRNA capping and blocking of RNA polymerase
is ribavirin effective against all viruses?
no, ribavirin is only effective against viruses that synthesize mRNA
adverse effects of ribavirin
Dose dependent anemia in oral and parenteral use.
Elevated Bilirubin
Teratogenicity
ribavirin has good CNS penetration. t/f
false. it has poor CNS penetration.
what are the 2 drug combinations for hepatitis A and B
Hepatitis B – Interferon or Lamivudine
Hepatitis C – Interferon + Ribavirin
what is an interferon. where is it used.
This is a naturally occurring glycoprotein that is synthesized by recombinant DNA technology
Utilized in management of Hepatitis B and C
MOA of interferon
IFN bind to ganglioside receptors on host cell membranes. They induce the production of enzymes that inhibit the translation of viral mRNA into viral proteins so halting viral replication.
what is the IFN half life
2-4 hrs
IFN is administered orally only. t/f
false. Administered Scut or IV but not orally.
what are the drug interactions of IFN
Potentiate bone marrow depression of other drugs such as Zidovudine
MOA of lamivudine
Cytosine analog (phosphorylated by host cell enzymes to the active form) that inhibits HBV DNA polymerase and HIV reverse transcriptase
uses of lamivudine
Used for Hepatitis B infections
Used for HIV infections in combination with other drugs.
lamivudine requires dose adjustment in renal failure. t/f
true
uses of acyclovir
HSV-1 HSV-2 Varicella-zoster virus (VZV) Epstein-Barr Virus DOC in HSV encephalitis Commonly used for genital herpes infections
MOA of acyclovir
Acyclovir is a guanosine analog that is phosphorylated by viral thymidine kinase enzyme
It is further di and tri phosphorylated by the host cells and competes with dGTP for viral DNA polymerase.
It becomes incorporated into the viral DNA causing premature DNA chain termination.
Irreversible binding of acyclovir to viral DNA polymerase inactivates the enzyme
acyclovir does not cross the BBB. t/f
false. it crosses the BBB
Valacyclovir side effects
Gi disturbances, thromcytopenic purpura
Foscarnet MOA
Reversibly inhibits viral DNA and RNA polymerases thereby inhibiting chain elongation.
foscarnet uses
Used for CMV retinitis and acyclovir-resistant HSV and Herpes zoster infections
ganicyclovir MOA
Acyclovir analog that inhibits DNA polymerase and is incorporated into DNA to decrease chain elongation
ganicyclovir uses
Used for CMV retinitis and CMV prophylaxis in transplant patients
MOA NRTIs
They are analogs of nucleosides or nucleotides lacking the 3’-OH group
Once they enter cells they are converted to triphosphate form by enzymes
Competes with equivalent host cell triphosphate substrates for DNA synthesis by viral reverse transcriptase.
name a drug used in prophylaxis of HIV for pregnant and lactating females and infants.
zidovudine, azidothymidine
AZT Adverse effects
GIT disturbances
Bone marrow depression – Blood disorders (anemia and neutropenia)
CNS – Insomnia, Dizziness, Headaches
moa lamivudine
It terminates synthesis of viral DNA by inhibition of reverse transcriptase of both HIV and HBV
name a drug for HIV ttt that does not affect mitochondrial DNA synthesis or bone marrow cells
lamivudine
MOA NNRTIs
Highly selective noncompetitive inhibitors of HIV-1 reverse transcriptase enzyme
They bind to reverse transcriptase enzyme leading to conformational changes and enzyme inhibition.
Do not require activation by cellular enzymes
treatment with ________ leads to _________ in CD$+ cells and ________ in viral load
efavirenz, increase, decrease
absorption of efavirenz decreases with fatty meals. t/f
false. increases
half life of efavirenz
t1/2 = 40 hours (once daily dosing)
efavirenz is teratogenic. t/f
true
MOA of indinavir/ nelfinavir
They inhibit HIV aspartyl protease enzyme.
This enzyme is responsible for cleavage of the viral polyprotein into essential enzymes and structural proteins
This prevents maturation of viral particles
Protease does not occur in host – useful target for selective intervention
indinavir/ nelfinavir are ___________ inhibitors.
HIV Protease Inhibitors
Buffalo Hump due to accumulation of fat at the base of the neck is due to…?
indinavir/ nelfinavir
