Abacavir, also known as abacavir base, is a medication used to treat HIV/AIDS. It is classified as a nucleoside reverse transcriptase inhibitor (NRTI) and is often used in combination with other antiretroviral drugs to control HIV infection. Abacavir works by interfering with the enzyme that the virus uses to replicate its genetic material, thereby slowing down the progression of the disease. Additionally, it helps to reduce the risk of transmission to others. Abacavir is generally well-tolerated, but it may cause adverse reactions in some individuals, so it should be used under medical supervision and monitoring.