AWD 131-138 is a partial agonist of benzodiazepine receptor [1].
Benzodiazepine (BZD) is a psychoactive drug and acts as positive allosteric modulators of the inhibitory neurotransmitter GABA by binding to a recognition site (BZD receptor) of the GABAA receptor chloride ionophore complex [1].
AWD 131-138 is a partial benzodiazepine receptor agonist with anticonvulsant and anxiolytic activity [1]. In Xenopus oocytes expressed recombinant γ-aminobutyric acid A (GABAA) receptors of ɑ1β2γ2, ɑ1β3γ2, ɑ2β2γ2, ɑ3β2γ2 and ɑ5β2γ2, AWD 131-138 stimulated GABA currents in a dose-dependent way and acts at the binding site for benzodiazepines. AWD 131-138 (10 μM) stimulated GABA currents up to 12-21% of the maximal stimulation achieved by diazepam [2].
In a dog seizure model, AWD 131-138 increased the pentylenetetrazole (PTZ) seizure threshold. AWD 131-138 (5 or 40 mg/kg) caused relatively mild abstinence symptoms, particularly at the lower dosage. In dogs with newly diagnosed epilepsy, AWD 131-138 significantly reduced seizure frequency and severity [3].
References:
[1]. Rundfeldt C, Löscher W. The pharmacology of imepitoin: the first partial benzodiazepine receptor agonist developed for the treatment of epilepsy. CNS Drugs, 2014, 28(1): 29-43.
[2]. Sigel E, Baur R, Netzer R, et al. The antiepileptic drug AWD 131-138 stimulates different recombinant isoforms of the rat GABA(A) receptor through the benzodiazepine binding site. Neurosci Lett, 1998, 245(2): 85-88.
[3]. Löscher W, Potschka H, Rieck S, et al. Anticonvulsant efficacy of the low-affinity partial benzodiazepine receptor agonist ELB 138 in a dog seizure model and in epileptic dogs with spontaneously recurrent seizures. Epilepsia, 2004, 45(10): 1228-1239.