Positive allosteric modulator of GABA B receptors. Increases the potency and efficacy of GABA at both native and recombinant GABA B receptors (EC 50 values are 5.37 and 4.60 μ M respectively) and enhances the inhibitory effect of the agonist L-baclofen in cultured cortical neurons. Reduces operant self-administration of ethanol in alcohol-preferring rats following i.p. administration.