Flumazenil. false is
It may be used in barbiturate poisoning as it acts on the same receptor i.e. GABAA Flumazenil is a highly selective competitive antagonist at benzodiazepine receptors so does not oppose sedation due to non benzodiazepine e.g., barbiturates alcohol. Gamma AminoButyric acid (GABA) is the most impoant inhibitory neurotransmitter in the C.N.S. comprising up of 40% of all synapses. Its main action is to inhibit transmission along neurons in which they are present. Normally proper functioning of the brain is ensured by a balance between the action of excitatory and inhibitory neurotransmitters. - Simply put, excitatory neurotransmitters conduct the impulses forward where as inhibitory neurotransmitters do not conduct the impulse ,forward. The GABAA receptor not only binds to the endogenous ligand GABA but is also the binding site for various other external ligands such as Benzodiazepenes, Barbiturates. (GABAA receptor has several binding sites) An impoant point to emphasize here is that though the benzodiazepine drugs bind to GABAA receptors; their binding site is distinct from the binding site of the endogenous GABA ligand. - In fact, it produces different effect on binding too. - When Benzodiazepenes bind to its site on the GABA receptor it does not directly increase the entry of chlorides rather it enhances the effectiveness of GABA producing a larger inhibitory effect. Other drugs that act on the GABAA benzodiazepine receptor complex Barbiturates too act on the GABAA receptor. - But their site of action is different from Benzodiazepenes. They also enhance the GABA.function but at high doses have the additional capacity directly to open the membrane chloride channel. This explains why barbiturates and alcohol are more toxic in overdose than the benzodiazepenes. Not only the binding site of benzodiazepenes is distinct from Barbiturates but the mechanism of action too is different. Benzodiazepenes Causing burst of chloride channel opening to occur more often. Barbiturates Causing duration of bursts of chloride channel opening to become longer. It is evident from the above diagram that though benzodiazepem and barbiturates act on the same receptor i.e., GABAA -benzodiazepem receptor complex, their binding site is site is quite distinct from each other. Once again, Even though benzodiazepenes and barbiturates act on the same receptor their binding site on the receptor is quite distinct from each other. - Flumazenil is highly selective competitive antagonist at benzodiazepene receptor, so it does not oppose sedation due to non benzodiazepenes e.g., barbiturates, alcohol. An impoant point: ? There is ceain other class of hypnotic that act on the same receptor site as the benzodiazepens on the GABAA benzodiazepene receptor complex, 50 their action too is blocked by Benzodiazepene antagonist i.e., Flumazenil. Non Benzodiazepene hypnotics that act at the GABAA- Benzodiazepene receptor complex. - Zopiclone - Zolpidem - Zaleplon
It is specific antagonist of BZD
It may be used in barbiturate poisoning as it acts on the same receptor i.e. GABAA
Given intravenously
Acts on GABAA receptor