An antiviral drug used to treat AIDS (see AIDS/HIV) and its related conditions, such as pneumocystis PNEUMONIA. The drug slows down the growth of human immunodeficiency virus (HIV) but does not cure the disease. It may be given intravenously or by mouth. Also called AZT, zidovudine has been in use since 1987, and it works by blocking the ENZYME that stimulates HIV to grow and multiply. It may cause ANAEMIA so regular blood tests are necessary.