This class of compounds is a common treatment for
viral diseases, most notably
HIV.
AZT is the most well known of the
nucleoside analogs (NAs), but they all have fairly similar overall structure. They follow the basic nucleoside
moiety, but are always 2',3'-dideoxy or dide
hydroxy, to prevent them from being incorporated into an elongating
DNA chain. Instead, they occupy the active site of
reverse transcriptase and prevent it from functioning. In general, this class of compounds is
toxic to the
bone marrow, requiring that they only be used when the disease is severe enough. Some examples of nucleoside analogs other than AZT include 2',3'-didehydro-3'-deoxythymidine (d4T) and 2',3'-dideoxyinosine (ddI), both of which seem to cause less marrow toxicity than AZT.
The antivirals which are used for the treatment of
herpes and
shingles(
zoster) are also nucleoside analogs (
acyclovir,
valacylovir aka
Valtrex), but are considerably different in structure from the HIV drugs.