(±)-Baclofen-d₄is intended for use as an internal standard for the quantification of (±)-baclofen by GC- or LC-MS. (±)-Baclofen is a GABA_Breceptor agonist (IC₅₀= 180 nM).¹It induces norepinephrine release from isolated rat atria (IC₅₀= 4.5 μM). (±)-Baclofen (10 mg/kg) increases muscle rigidity in spastic mice.²It inhibits the norepinephrine-induced group II flexor reflex in anesthetized rats.³(±)-Baclofen also reduces cocaine-induced hyperlocomotion in rats and binge-like ethanol intake in mice.^4,5Formulations containing baclofen have been used to treat muscle spasms caused by multiple sclerosis and spinal cord injury.

1.Hill, D.R., and Bowery, N.G.3H-baclofen and 3H-GABA bind to bicuculline-insensitive GABAB sites in rat brainNature290(5802)(1981) 2.Biscoe, T.J., and Fry, J.P.Some pharmacological studies on the spastic mouseBr. J. Pharmacol. 75(1)23-25(1982) 3.Sakitani, K.The effects of centrally acting muscle relaxants on the intrathecal noradrenaline-induced facilitation of the flexor reflex mediated by group II afferent fibers in ratsJpn. J. Pharmacol.63(3)369-376(1993) 4.Lhuillier, L., Mombereau, C., Cryan, J.F., et al.GABAB receptor-positive modulation decreases selective molecular and behavioral effects of cocaineNeuropsychopharmacology32(2)388-398(2007) 5.Moore, E.M., and Boehm, S.L., IISite-specific microinjection of baclofen into the anterior ventral tegmental area reduces binge-like ethanol intake in male C57BL/6J miceBehav. Neurosci.123(3)555-563(2009)