Emtricitabine is a (deoxy)cytidine
analogue. It has a fluoride group attached to carbon 5
of the pyrimidine ring of cytosine.
It is called (5-fluoro-) thiacytidine
because it has a sulphur atom in the deoxyribose section, at the same place that the normal DNA molecule forms phosphodiester bonds
with the next nucleotide.
It may be described as 2'-deoxy-5-fluoro-3'-thiacytidine
It is used as a nucleoside reverse transcriptase inhibitor (NRTI)
because it acts as a selective inhibitor of HIV's reverse transcriptase enzyme, which converts viral RNA into DNA, to be incorporated into human T lymphocyte cells.
Emtricitabine in combination with other drugs can be used as highly active antiretroviral therapy
(HAART) treatments for HIV.