Salvinorin A

Cerebral vasospasm occurs frequently after subarachnoid hemorrhage (SAH) secondary to rupture of an intracranial aneurysm. The possibility that calcium entry blockers may be effective on a delayed cerebral vasospasm and the effectiveness of intrathecal administration of the calcium antagonist nifedipine and its analog nimodipine on a vasospasm has been shown from a clinical point of view. Fasudil is a class of calcium antagonists different from the calcium entry blockers.

In vitro: The inhibitory effects of fasudil on contractile responses to various agonists were examined on strips of rabbit aorta. The concentration-response curves to 5-hydroxytryptamine, prostaglandin F2alpha, histamine, angiotensin II, noradrenaline and dopamine were concentration-dependently shifted to the right in the presence of fasudil [1].

In vivo: Intra-coronary administration of fasudil to dog dose-dependently increased coronary blood flow, with no effect on mean blood pressure or heart rate. Intra-coronary infusion of atropine, diphenhydramine or propranolol did not modify the in vivo coronary vasodilator response to fasudil [1].

Clinical trial: The previous results suggested that fasudil was equally or more effective than nimodipine for the prevention of cerebral vasospasm and subsequent ischemic injury in patients undergoing surgery for SHA [2].
Reference:
[1] Asano T, Suzuki T, Tsuchiya M, Satoh S, Ikegaki I, Shibuya M, Suzuki Y, Hidaka H. Vasodilator actions of HA1077 in vitro and in vivo putatively mediated by the inhibition of protein kinase. Br J Pharmacol. 1989 Dec;98(4):1091-100.
[2] Zhao J, Zhou D, Guo J, Ren Z, Zhou L, Wang S, Zhang Y, Xu B, Zhao K, Wang R, Mao Y, Xu B, Zhang X; Fasudil Aneurysmal Subarachnoid Hemorrhage Study Group. Efficacy and safety of fasudil in patients with subarachnoid hemorrhage: final results of a randomized trial of fasudil versus nimodipine. Neurol Med Chir (Tokyo). 2011;51(10):679-83.