Verapamil hydrochloride is an alpha-adrenergic receptor (alpha-AR) antagonist and calcium channel protein inhibitor that blocks the L-type Ca2+ channels in smooth and cardiac muscle cells. Verapamil is an antiarrhythmic agent and vasodilator known to reduce the renal clearance of digoxin and induce apoptosis in primary and metastatic colon adenocarcinoma human cell lines in vitro. It has been observed that verapamil can induce currents by itself, presumably by acting on the potassium and chloride leakage. Verapamil has also been used as an inhibitor of drug efflux pump proteins such as Mdr (P-glycoprotein). Verapamil is a substrate of CYP3A4 and CYP2C6. It is also used in fluorescent cell sorting for DNA content, as it blocks efflux of a variety of DNA-binding fluorophores such as Hoechst 33342. Recent research has shown verapamil to be an effective treatment for diabetes in animal models. Verapamil helps treat diabetes by limiting TXNIP expression.