Carbenoxolone

Carbenoxolone, a synthetic derivative of glycyrrhetinic acid, is a licensed drug (in the UK) for oesophageal ulceration and inflammation. Other uses include treatment of oral and perioral lesions.

Carbenoxolone (aka Carbenoxolone, CBX) is also used as a blocker of the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD), of pannexon membrane channels (comprising 6 subunits of pannexin) and the related innexon channels (consisting of invertebrate innexins), and at higher concentrations, as a blocker of connexon channels ("hemichannels" made up of 6 connexin subunits each) and of gap junctions (2 connexons joined together).

Nootropic effects
Carbenoxolone has also been investigated for nootropic effects.

This research started from an observation that long-term exposure to glucocorticoids may have negative effects on cognition. Carbenoxolone may decrease the amount of active glucocortocoid in the brain, because the drug inhibits 11Beta-hydroxysteroid dehydrogenase type 1, an enzyme which activates cortisol from cortisone, a glucocorticoid. In the research trial investigating this use of carbenoloxone, it was shown that the drug improved verbal fluency in elderly healthy men (aged 55–75). In type 2 diabetics aged 52–70, the drug improved verbal memory. However, potassium-sparing diuretic amiloride was co-administered with carbenoxolone, since carbenoxolone used by itself may cause hypertension by increasing cortisol in the kidneys.