Pharmacovigilance database search discloses ClC-K channels as a novel target of the AT1 receptor blockers valsartan and olmesartan

BACKGROUND AND PURPOSE: Human ClC-K chloride channels are highly attractive targets for drug discovery as they have a variety of important physiological functions and are associated with genetic disorders. These channels are crucial in the kidney as they control chloride reabsorption and water diuresis. In addition, loss-of-function mutations of CLCNKB and BSND genes cause Bartter's syndrome (BS), whereas CLCNKA and CLCNKB gain-of-function polymorphisms predispose to a rare form of salt sensitive hypertension. Both disorders lack a personalized therapy that is in most cases only symptomatic. The aim of this study was to identify novel ClC-K ligands from drugs already on the market, by exploiting the pharmacological side activity of drug molecules available from the FDA Adverse Effects Reporting System database. EXPERIMENTAL APPROACH: We searched for drugs having a Bartter-like syndrome as a reported side effect, with the assumption that BS could be causatively related to the block of ClC-K channels. The ability of the selected BS-causing drugs to bind and block ClC-K channels was then validated through an integrated experimental and computational approach based on patch clamp electrophysiology in HEK293 cells and molecular docking simulations. KEY RESULTS: Valsartan and olmesartan were able to block ClC-Ka channels and the molecular requirements for effective inhibition of these channels have been identified. CONCLUSION AND IMPLICATIONS: These results suggest additional mechanisms of action for these sartans further to their primary AT1 receptor antagonism and propose these compounds as leads for designing new potent ClC-K ligands.