A synthetic chlorophenyl-butanoic acid derivative with muscle relaxant activity. Baclofen acts as a gamma-aminobutyric acid (GABA) agonist specific for GABA-B receptors in the central nervous system (CNS). At spinal and supraspinal sites, this agent reduces excitatory transmission. or A vaccine used to prevent tuberculosis (TB) in people who are at a high risk of TB or where TB is common. It is rarely given in the U.S. It is made from a weakened form of a bacterium called Mycobacterium bovis (bacillus Calmette-Guérin), which is similar to the bacteria that cause TB. The vaccine may help the body’s immune system make antibodies to destroy the TB bacteria. It also may help the immune system kill cancer cells and is being studied in the treatment of melanoma. Also called BCG vaccine.