Nimodipine (also known as Nimotop or Periplum) is a dihydropyridine calcium channel blocker that may not be used for treatment of hypertension. Compared to other DHP CCBs, nimodipine is more active in the cerebral vasculature than in the periphery. This may be due to its high lipophilicity and ability to penetrate the blood brain barrier. This unique property of nimodipine led to clinical studies for its use to improve neurological outcomes in patients following subarachnoid hemorrhage from ruptured intracranial aneurysms. While it has been approved as adjunct treatment for this indication, the exact mechanism by which it exerts these effects is unclear. Nimodipine has little effect on cardiac myocytes and conduction cells at therapeutic sub-toxic concentrations. Nimodipine binds the major channel in muscle cells: L-type calcium channels. Binding of Nimodipine on L-type calcium channels can change channels' confirmation to its inactive form, so that the channel couldn't faciltate the influx of calcium ions, which leads to decreased arterial smooth muscle contractility and subsequent vasoconstriction. Activated mysoin light chain kinase (MLCK) is required for muscle contraction since it can catalyze the phosphorylation of the regulatory light chain subunit of myosin. Without calcium ions in muscle cell, calmodulin couldn't form the calcium-bound calmodulin, which is required for binding and activating MLCK. Lack of initial influx of calcium can also reduce the level of contractile activity of muscle cells and results in vasodilation, which ultimately lead to overall decresing in blood pressure.

Nimodipine Pathway References

Striated Muscle Contraction References