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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


spectrum of activity of acyclovir

herpes virus
antiviral treatment in immunosuppressed is continuous
used for herpes cold sore
infection with chicken pox etc.