Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2010 Dec;59(7-8):635-9.
doi: 10.1016/j.neuropharm.2010.07.024. Epub 2010 Aug 7.

Occupancy of human brain GABA(A) receptors by the novel α5 subtype-selective benzodiazepine site inverse agonist α5IA as measured using [¹¹C]flumazenil PET imaging

W Eng  1 , J R Atack, M Bergstrom, S Sanabria, L Appel, G R Dawson, D Sciberras, R J Hargreaves, B Langstrom, H D Burns
Affiliations

Occupancy of human brain GABA(A) receptors by the novel α5 subtype-selective benzodiazepine site inverse agonist α5IA as measured using [¹¹C]flumazenil PET imaging

W Eng et al. Neuropharmacology. 2010 Dec.

Abstract

GABA(A) receptor α5-selective inverse agonists enhance cognitive performance in pre-clinical species. However, a key aspect of the clinical development of such compounds is the demonstration that in man such compounds are devoid of the anxiogenic-like activity associated with non-selective inverse agonists such as FG 7142. The triazolophthalazine α5IA (3-(5-methylisoxazol-3-yl)-6-[(1-methyl-1,2,3-triazol-4-yl)methyloxy]-1,2,4-triazolo[3,4-a]phthalazine) is an α5-selective inverse agonist which enhances cognitive performance in rodents and encouragingly in human Phase I Safety and Tolerability studies it was devoid of the anxiogenic-like activity associated with FG 7142. However, in order to appropriately interpret this latter observation, it was considered important to demonstrate that the absence of anxiogenic-like activity occurs at significant levels of receptor occupancy. Consequently, the occupancy of human brain GABA(A) receptors was measured using [¹¹C]flumazenil positron emission tomography in three healthy normal young male volunteers following a single oral dose of 2 mg α5IA. One hour after dosing, mean occupancy levels were 53% and this fell to 16% by 8 h post-dose, with the plasma α5IA concentration corresponding to 50% occupancy being 10 ng/mL. These data clearly show that an α5-selective inverse agonist is not associated with anxiogenic-like side effects at doses that give ~50% occupancy.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

Substances

LinkOut - more resources