Benzodiazepine acts through which receptor:

Ans: b (GABA) Ref: KDT, 6th ed, p. 395BZDs act by enhancing presynaptic/postsynaptic inhibition through a BZD receptor which is an integral part of the GABAA receptor-Cl- channel complex.They have GABA facilitatory action and no GABA mimetic action i.e. the BZD's increase the frequency of Cl channel opening induced by sub maximal concentrations of GABA and enhance GABA binding to GABAA receptor but they do not themselves increase Cl- conductance.Flumazenil is a competitive antagonist at BZD siteCarboline b - is an inverse agonist at BZD siteBicuculline - Competitive antagonist at GABAA receptorMuscimol - acts as agonist at GABAA site.Drugs active at the benzodiazepine receptor may be divided into four categories based on their elimination half-lives:(1) Ultra short acting: Midazolam(2) Short acting (t]/2 <6 hours): Triazolam, the nonbenzodiazepine zolpidem (t1/2 =2 hours) and zopiclone (t1/2 = 5-6 hours).(3) Intermediate-acting (t1/2 = 6-24 hours): Estazolam and temazepam.(4) long-acting (t1/2 >24 hours):Flurazepam, diazepam, and quazepam.Flurazepam has the longest half life of 50-100 hrs.