Barnidipine

Barnidipine is a lipophilic 1,4-dihydropyridine calcium antagonist that is characterized by a slow onset of action and a strong and long-lasting binding to the L-type calcium channels. It displays high affinity for the channels expressed in the smooth muscle cells in the vascular wall. Its main mechanism of action arises from the reduction of peripheral vascular resistance secondary to its vasodilatory actions.

Calcium ion influx via L-subtype ‘voltage-operated’ channels in the excitable membranes of the smooth muscle cells promotes the formation of calcium-dependent formation of cross-bridges between myosin and actin which are the two major contractile proteins that drive contraction. By blocking the L-type 'voltage-dependent' calcium channels, barnidipine selectively blocks the calcium ion influx in the smooth muscle cells and inhibits the activation of contractile proteins. It is suggested that barnidipine displays a high affinity to the inactivated state of the channel. Like other dihydropyridine calcium antagonists, barnidipine is predicted to interact with the alpha 1-C subunit of the L-type calcium channels. Alpha 1-C subunit of the channel is predicted to reside within the bilayer or channel pore at a location closer to the extracellular rather than the intracellular face of the membrane. Its lipophilicity is likely a reason why barnidipine displays a slow onset and long duration of action. Being a highly lipophilic molecule with an octanol/water partition coefficient of 2000, barnidipine is expected to accumulate in the cell membrane and consequently, gains access to its target receptor in a slow manner.