3'-Azido-2',3'dideoxyuridine (AzdU or CS-87) is a nucleoside analog that has been shown to inhibit HIV replication in blood cells. The antiviral drug is thought to competitively inhibit reverse transcriptase of HIV by terminating the new DNA sequences made. AzdU has been shown to have a low level of toxicity to bone marrow cells while decreasing replication specifically in the peripheral blood mononuclear cells. An advantage of AzdU is that is has been shown to pass through the blood-brain barrier which if proven successful could be an additional method of reducing HIV replication in the brain and spine. Progress on AzdU has been slow, AzdU has not been approved by the FDA, however it is still in clinical trial phases. AzdU is not a cure to HIV, but may result in lengthening the lives of those infected by HIV by slowing the progression of the disease.

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