Could clazosentan, first approved in Japan, improve neurological prognosis after subarachnoid hemorrhage in combination with modified water-electrolyte management?

An aneurysmal subarachnoid hemorrhage (aSAH) is a devastating event associated with a high mortality and morbidity rate. Though numerous medications are used to prevent cerebral vasospasm and vasospasm-related cerebral infarction after aSAH, no effective pharmacological treatment has been established. Clazosentan, a highly selective endothelin receptor type A antagonist, was approved for use in Japan in April 2022 based on results of two pivotal randomized, placebo-controlled phase 3 studies (JapicCTI-163369, JapicCTI-163368). These studies indicated that clazosentan significantly reduced the incidence of vasospasm-related morbidity and all-cause mortality after aneurysm coiling and clipping. Clazosentan is thus expected to become a “game changer” for improving the neurological prognosis after aSAH. However, other reports indicate that even when clazosentan or nimodipine are administered for prophylaxis against delayed neurological decline, patients treated with increased colloid administration or hypertonic saline (3% sodium chloride) load exhibit poor functional outcome and higher mortality, suggesting that extra fluid and sodium derived from prophylactic colloid administration contribute to negative outcomes after aSAH. Pharmacological treatments such as clazosentan in addition to perioperative management involving delivery of less water and sodium might be crucial for achieving better outcomes than conventional therapy. Based on a literature review, we present here the future perspectives regarding clazosentan and the necessity for modifying management of the water-electrolyte balance by focusing on endothelin-1 and blood–brain barrier disruption.