Flashcards in Acyclovir Deck (11):
What does acyclovir resemble?
Deoxyguanosine - but doesn't have the 3' hydroxyl group
When does acyclovir become activated?
When it comes into contact with thymidine kinase
How is acyclovir activated - the process?
1) it enter the cell and changes in the presence of thymidine kinase (has high affinity for it) to form acyclo-guanosine monophosphate (acyclo-GMP)
2) it is converted into acyclo GDP using guanylate kinase
3) the acyclo gdp is converted into acyclo gtp by phosphotransferase and is active
3) acyclo gtp works well with viral dna polymerase not host hence it is incorporated
What viral infections can acyclovir be used against?
herpes - herpes simplex (1+2), cytomegalovirus, varicella zoster, human herpes virus and EBV
What kind of viruses are herpes and what are they characterised by?
double stranded DNA
What is selective toxicity?
Preferential inhibition of metabolic processes of pathogen opposed to host
Give examples of other nucleoside analogues
guancylcovir and zidovudine (thymidine analogue)
Why does acyclovir work for herpes viruses?
- they code for their own polymerase
- they code for their own thymidine kinase
What does thymidine kinase do?
creates a nucleotide by adding a phosphate group to a nucleoside
Mechanism of resistance to acyclovir
mutations in TK or DNA polymerase