Voltage-dependent L-type Ca²⁺ channels play an important role Ca²⁺ influx. L-type calcium currents typically require a strong depolarization for activation and are long-lasting¹.

The common pharmacological profile of L-type channels is determined by the α1 subunit, which forms the Ca²⁺ selective pore, and is encoded by one of the Ca_V1 (α 1S) channel genes². Ca_v1.2 (CACNA1C) in humans is widely expressed in cardiac myocytes, smooth muscle myocytes, endocrine cells, neuronal cell bodies and proximal dendrites¹.

Flavoxate hydrochloride is widely used for the treatment of urinary frequency³. Flavoxate increases urinary bladder capacity primarily by suppressing the micturition reflex through modulation of the central nervous system⁴. However, in addition to its activity in the CNS, it possesses direct inhibitory effects on the detrusor muscle. Flavoxate causes a detrusor relaxation through inhibition of L-type Ca⁺² (Ca_V1.2) channels in human urinary bladder detrusor smooth muscle, in a concentration-dependent manner⁵.