<prompt> All acts through GABAA receptors except -BenzodiazepinesBarbituratesZopiclonePromethazine  <response>: Ans. is d i.e., Promethazine GABA RECEPTORS o There are two types of GABA receptors:? 1 GABAA receptors :- These are intrinsic CI channels and when open cause increase in CI conductance and CNS depression. Drugs acting on these receptors are - i Agnoists :- barbiturates, benzodiazepines, zopiclone, zolpidem, zoleplon, muscimol ii Inverse agonist:- 0-carboline iii Antagonist :- Flumazenil. iv Other drugs :- Alphaxalone, alcohol, anticonvulsants Gabapentine, vigabaterine, Picrotoxin 2 GABAB receptors :- These are G-protein coupled receptors. Baclofen is agonist and saclofen is antagonist on these receptors. 