Chemistry:Imidazenil
Imidazenil[1] is an experimental anxiolytic drug which is derived from the benzodiazepine family, and is most closely related to other imidazobenzodiazepines such as midazolam, flumazenil, and bretazenil.
Imidazenil is a highly potent benzodiazepine receptor partial agonist[2] with an unusual profile of effects, producing some of the effects associated with normal benzodiazepines such as anticonvulsant and anxiolytic effects, yet without any notable sedative or amnestic[3] effects. In fact, imidazenil blocks the sedative effects of diazepam, yet without lowering the convulsion threshold,[4] and so potentially could be a more flexible antidote than the antagonist flumazenil which is commonly used to treat benzodiazepine overdose at present.
Imidazenil has not yet been developed commercially for use in humans, however it has been suggested as a safe and effective treatment for anxiety,[5] a potent yet non-sedating anticonvulsant which might be particularly useful in the treatment of poisoning with organophosphate nerve agents,[6][7] and as a novel treatment for schizophrenia.[8]
In rats, imidazenil has been demonstrated to have low tolerance or dependence liability, unlike other benzodiazepine receptor agonist ligands, such as diazepam, bretazenil.[9]
Pharmacodynamics
Imidazenil is selective over the type of GABAA receptor it acts on. It acts as a partial agonist on those with a α1β2γ2S composition and as a full agonist on those with a α5β2γ2S composition.[4] Its action can be compared to that of clobazam, another anxioselective benzodiazepine. Clobazam's active metablite N-desmethylclobazam has lower affinity on receptors with an α1 subunit compared to those with an α2.[10][11] It is believed that the subjective, ataxic, and sedative properties are mediated via α1-containing receptors, while the anxiolytic effects are mediated via the ones with α2, α3, or α5.[4]
See also
References
- ↑ US patent 5317018
- ↑ "Imidazenil, a new anxiolytic and anticonvulsant drug, attenuates a benzodiazepine-induced cognition deficit in monkeys". The Journal of Pharmacology and Experimental Therapeutics 273 (3): 1307–12. June 1995. doi:10.1016/S0022-3565(25)09636-3. PMID 7791102.
- ↑ "Comparison of the effects of full and partial allosteric modulators of GABA(A) receptors on complex behavioral processes in monkeys". Behavioural Pharmacology 6 (4): 323–332. June 1995. doi:10.1097/00008877-199506000-00003. PMID 11224341.
- ↑ 4.0 4.1 4.2 "Imidazenil: an antagonist of the sedative but not the anticonvulsant action of diazepam". Neuropharmacology 49 (3): 425–9. September 2005. doi:10.1016/j.neuropharm.2005.04.005. PMID 15964602.
- ↑ "Anxioselective compounds acting at the GABA(A) receptor benzodiazepine binding site". Current Drug Targets. CNS and Neurological Disorders 2 (4): 213–32. August 2003. doi:10.2174/1568007033482841. PMID 12871032.
- ↑ "Effects of imidazenil, a new benzodiazepine receptor partial agonist, in the treatment of convulsions in organophosphate intoxications". Neurotoxicity Research 2 (1): 17–22. 2000. doi:10.1007/bf03033323. PMID 15545002.
- ↑ "Imidazenil: a potent and safe protective agent against diisopropyl fluorophosphate toxicity". Neuropharmacology 46 (3): 397–403. March 2004. doi:10.1016/j.neuropharm.2003.09.010. PMID 14975695.
- ↑ "GABAergic dysfunction in schizophrenia: new treatment strategies on the horizon". Psychopharmacology 180 (2): 191–205. July 2005. doi:10.1007/s00213-005-2212-8. PMID 15864560.
- ↑ Auta J, Giusti P, Guidotti A, Costa E (September 1994). "Imidazenil, a partial positive allosteric modulator of GABAA receptors, exhibits low tolerance and dependence liabilities in the rat". J Pharmacol Exp Ther 270 (3): 1262–9. doi:10.1016/S0022-3565(25)22535-6. PMID 7932179.
- ↑ "The clobazam metabolite N-desmethyl clobazam is an α2 preferring benzodiazepine with an improved therapeutic window for antihyperalgesia". Neuropharmacology 109: 366–375. October 2016. doi:10.1016/j.neuropharm.2016.07.004. PMID 27392635.
- ↑ "A pharmacological profile of clobazam (Mystan), a new antiepileptic drug". Nihon Yakurigaku Zasshi. Folia Pharmacologica Japonica 118 (2): 117–22. August 2001. doi:10.1254/fpj.118.117. PMID 11530681.
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