Antivirals Flashcards
Aciclovir is an analogue of which DNA base pair?
Guanine
Is aciclovir active on administration?
No. Needs to be phosphorylated by viral thymadine kinase
MOA of aciclovir?
Inhibits DNA synthesis by terminating the chain and inhibiting DNA polymerase
Most common mechanism for resistance against aciclovir?
Virus becomes deficient in TK and uses the host’s TK for replication
AZT full name?
Azidothymidine
What does NRTI and NNRTI stand for?
(Non-)nucleoside reverse transcriptase inhibitor
Which base pair is AZT an analogue of?
Thymidine
MOA of AZT?
Inhibits the viral reverse transcriptase enzyme
Role of the viral reverse transcriptase enzyme?
Converts the viral RNA into DNA, which then gets incorporated into the host cell’s genome
How does azidothymidine get activated?
The host’s thymadine kinase phosphorylates it. (Different to aciclovir which uses the viral TK)
Name an NNRTI
Nevirapine
Is nevirapine a prodrug?
No
MOA of saquinavir?
HIV protease inhibitor - blocks the enzyme that hydrolyses hiv proteins into smaller parts to allow for assembly
Which drug develops resistance rapidly, so it commonly combined with AZT?
Saquinavir
Explain HAART
Highly active antiretroviral therapy. Multi-drug approach to treat HIV - limits resistance and reduces doses required
Compare oseltamivir and zamamivir
Both are neuraminidase inhibitors. Oseltamivir is oral, whereas zamamivir is inhaled
Explain how neuraminidase inhibitors work
They prevent the cleavage of the bond between HA and sialic acid. This means the virion is stuck to the outside of the infected cell, which allows it to be targeted by the immune system
MOA of amantidine?
Blocks the M2 channel, preventing the endocytosed vehicle from becoming acidic, which prevents the uncoating of the virus
Discuss amantidine resistance
Pretty much all influenza strains are now resistant to amantidine. A single amino acid change in the M2 ion channel is all it takes to modify it and prevent amantidine from binding
MOA of chloroquine and mefloquine?
They are anti malarials. They inhibit the haem polymerase enzyme which prevents the parasite’s from detoxifying free haem, killing the parasite
Role of haem polymerase?
Polymerases the free haem proteins into haemozoin crystals
Compare the MOAs of the combination product atovaquone and proguanil
Ato - inhibits the production of ATP in the parasite by interrupting the mitochondrial transport chain
Pro - inhibits the parasite’s DHFR enzyme
