Nimodipine is a medication belonging to the class of calcium channel blockers. It is primarily used to prevent and treat vasospasm, a condition in which blood vessels in the brain constrict, following a subarachnoid hemorrhage (bleeding in the space surrounding the brain).

By blocking calcium channels in blood vessel walls, nimodipine helps to relax and widen the blood vessels, improving blood flow to the brain and reducing the risk of vasospasm-related complications such as ischemia (reduced blood flow) and stroke