Baclofen, sold under the brand name Lioresal, among others is a central nervous system depressant used as a skeletal muscle relaxant. It is primarily used to treat spasticity. It is also used as a muscle relaxant by compounding pharmacies in topical pain creams. It is a GABA receptor agonist, specifically of the GABAB receptors. Its beneficial effects in spasticity result from actions at spinal and supraspinal sites. It is a derivative of γ-aminobutyric acid (GABA). A beneficial property of baclofen is that tolerance to its muscle-related therapeutic benefits does not seem to occur to a significant degree — baclofen retains its therapeutic anti-spasmodic effects even after many years of continued use. Newer studies, however, indicate that tolerance may develop in some people receiving intrathecal baclofen treatment. As of 2015 the cost for a typical course of treatment in the United States is less than 25 USD.