SL651498 was identified as a drug development candidate from a research program designed to discover subtype-selective GABA(A) receptor agonists for the treatment of generalized anxiety disorder and muscle spasms. SL651498 displayed high affinity for GABA(A) receptors containing alpha(1) and alpha(2 subunits, and weaker affinity for alpha5-containing GABA(A) receptors, it behaved as a full agonist at recombinant t GABA(A) receptors containing alpha(2) and alpha(3) subunits, and as a partial agonist at recombinant GABA(A) receptors expressing alpha(1) and alpha(5) subunits. It was shown, that SL651498 represented a promising alternative to agents currently used for the treatment of anxiety disorders and muscle spasms without the major side effects seen with classical benzodiazepines).

4-Methoxymethamphetamine (PMMA, para-Methoxymethamphetamine) is a stimulant and psychedelic drug closely related to the amphetamine-class serotonergic drug para-methoxyamphetamine (PMA). Little is known about the pharmacological properties, metabolism, and toxicity of 4-Methoxymethamphetamine. Because of its structural similarity to para-methoxyamphetamine, which has known toxicity in humans, it is thought to have considerable potential to cause harmful side effects or death in overdose. In the early 2010s, a number of deaths in users of the drug MDMA were linked to misrepresented tablets and capsules of 4-Methoxymethamphetamine. In 2010–2013, a cluster of 29 fatal poisonings related to the toxic designer drug 4-Methoxymethamphetamine was revealed in Norway. The toxicity of PMMA is regarded as substantially higher than for amphetamine, methamphetamine, and MDMA, as indicated by 131 fatal and 31 nonfatal poisonings associated with the abuse of 4-Methoxymethamphetamine worldwide. The toxicity of 4-Methoxymethamphetamine is positively correlated with the 4-Methoxymethamphetamine dose and the blood drug level, but the existing literature indicates that certain human subjects may have an increased risk of 4-Methoxymethamphetamine toxicity. 4-Methoxymethamphetamine, like PMA most likely acts as a selective serotonin releasing agent (SSRA) with weak effects on dopamine and norepinephrine transporters. However, relative to MDMA, it is considerably less effective as a serotonin releaser with properties more akin to a reuptake inhibitor in comparison. It evokes robust hyperthermia while producing only modest hyperactivity and serotonergic neurotoxicity, substantially lower than that caused by MDMA.