Baclofen, a derivative of gamma-aminobutyric acid (GABA), is a muscle relaxant used to treat spasticity. Marketed with brand names such as Kemstro, Lioresal or Gablofen, the drug has also shown effectiveness in the treatment of alcoholism. This certified solution standard is suitable for use as an internal standard in quantitative mass spectrometry-based testing applications in clinical toxicology, forensic analysis, pharmaceutical research or diagnostic testing.