2-Ethyl-5,7-dimethyl-3H-imidazo[4,5-b]pyridine is a nonpeptidic angiotensin II receptor antagonist.

Angiotensin II is the critical pressor substance of the renin-angiotensin system (RAS). The angiotensin II system, a proteolytic cascade regulating hemodynamics and water and electrolyte balance, is able to contribute to hypertensive states in human. The effects of the octapeptide angiotensin I1 includs cardiac stimulation, vasoconstriction, stimulation of aldosterone synthesis and release, as well as renal reabsorption of sodium.

In vitro: In a previous study, 2-ethyl-5,7-dimethyl-3H-imidazo[4,5-b]pyridine was synthezed by reduction of 2-amino-3-nitropyridine derivatives to the corresponding diaminopyridine which was then condensed with an appropriate carboxylic acid in polyphosphoric acid. In vitro activity study showed that 2-Ethyl-5,7-dimethyl-3H-imidazo[4,5-b]pyridine was a nonpeptidic angiotensin II receptor antagonist whose imidazo[4,5-b]pyridine scaffold had been used to examine plenty of positional substitutions in the development of orally active, long duration antihypertensive agents [1].

In vivo: Up to now, there is no animal in vivo data reported.

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Mantlo, N. B.,Chakravarty, P.K.,Ondeyka, D.L., et al. Potent, orally active Imadazo[4,5-b]pyridine-based angiotensin II receptor antagonists. Journal of Medicinal Chemistry 34(9), 2919-2922 (1991).