Abacavir (Ziagen)

Abacavir is an anti-HIV drug that reduces the amount of virus in the body. Anti-HIV drugs such as abacavir slow down or prevent damage to the immune system and reduce the risk of developing AIDS-related illnesses.

Abacavir belongs to a class of drugs known as nucleoside reverse transcriptase inhibitors (NRTIs). When HIV infects a cell, the enzyme reverse transcriptase copies the viral single-stranded RNA genome into double-stranded viral DNA. This viral DNA is then integrated into the CD4 chromosomal DNA and can go on to reproduce in the body. Four natural nucleosides complete the DNA synthesis: adenosine, cytidine, guanosine, and thymidine. An NRTI drug substitutes a defective version of one of the nucleosides, causing premature termination of the proviral DNA chain.

In July 1999, abacavir was approved by the European Union licensing body for use in combination with other anti-HIV drugs. The drug was licensed in the United States in December 1998. Once-daily abacavir was also approved in the European Union in November 2004.

Abacavir was previously known by the codename 1592U89 and has been registered under the trade name Ziagen. It is made by GlaxoSmithKline, the company that also produces AZT (zidovudine, Retrovir) and 3TC (lamivudine, Epivir).

A pill that combines 300mg abacavir, 150mg 3TC and 300mg AZT called Trizivir, is also available from GlaxoSmithKline. It was approved in the United States in November 2000 and in the European Union in March 2001.

GlaxoSmithKline also produces a fixed-dose combination of 600mg abacavir with 300mg 3TC, which is suitable for once-daily dosing. It is marketed as Kivexa  in the European Union, where it was licensed in December 2004. The same combination tablet is called Epzicom in the United States, where it was approved for use in August 2004.

Abacavir is recommended by WHO as an alternative NRTI in first-line therapy, either as part of an NRTI backbone for use with NNRTIs or as part of a triple nucleoside regimen.^[1]