Intraventricular Nimodipine for Aneurysmal Subarachnoid Hemorrhage: Results of the NEWTON Phase 1/2a Study

Clinical Pharmacology of Clazosentan, a Selective Endothelin A Receptor Antagonist for the Prevention and Treatment of aSAH-Related Cerebral Vasospasm

Aneurysmal subarachnoid hemorrhage (aSAH) may lead to cerebral vasospasm and is associated with significant morbidity and mortality. It represents a major unmet medical need due to few treatment options with limited efficacy. The role of endothelin-1 (ET-1) and its receptor ET_A in the pathogenesis of aSAH-induced vasospasm suggests antagonism of this receptor as promising asset for pharmacological treatment. Clazosentan is a potent ET_A receptor antagonist for intravenous use currently under development for the prevention of aSAH-induced cerebral vasospasm. The pharmacokinetics of clazosentan are characterized by an intermediate clearance, a volume of distribution similar to that of the extracellular fluid volume, dose-proportional exposure, an elimination independent of drug-metabolizing enzymes, and a disposition mainly dependent on the hepatic uptake transporter organic anion transport polypeptide 1B1/1B3. In healthy subjects, clazosentan leads to an increase in ET-1 concentration and prevents the cardiac and renal effects mediated by infusion of ET-1. In patients, it significantly reduced the incidence of moderate or severe vasospasm as well as post-aSAH vasospasm-related morbidity and mortality. Clazosentan is well tolerated up to the expected therapeutic dose of 15 mg/h and, in aSAH patients, lung complications, hypotension, and anemia were adverse events more commonly reported following clazosentan than placebo. In summary, clazosentan has a pharmacokinetic, pharmacodynamic, and safety profile suitable to become a valuable asset in the armamentarium of therapeutic modalities to prevent aSAH-induced cerebral vasospasm.

Cerebrospinal Fluid Concentrations of Nimodipine Correlate With Long-term Outcome in Aneurysmal Subarachnoid Hemorrhage: Pilot Study

OBJECTIVES

The aim was to evaluate plasma and cerebrospinal fluid (CSF) nimodipine concentrations in patients with aneurysmal subarachnoid hemorrhage and their correlation with clinical outcome.

METHODS

Nimodipine infusion was started at 1 mg/h and increased up to 2 mg/h and continued up to 21 days in surviving patients. Arterial and CSF samples were collected at least after 24 hours of stable nimodipine dosing. Delayed cerebral ischemia and vasospasm were documented by new neurological deficits and neuroimaging. The clinical outcome was assessed at 9 months by the modified Rankin scale.

RESULTS

Twenty-three patients were enrolled. Nimodipine dose was 13 to 38 μg/kg per hour. Nimodipine arterial and CSF concentrations were 24.9 to 71.8 ng/mL and 37 to 530 pg/mL, respectively. Dose did not correlate with arterial or CSF concentrations. Arterial concentrations did not correlate with corresponding CSF concentrations. Doses and arterial concentrations did not correlate with the clinical outcome and were not associated with the occurrence of delayed cerebral ischemia. However, patients with no significant disability after 9 months of hemorrhage showed significantly higher CSF nimodipine concentrations (P = 0.015) and CSF-to-plasma ratios (P = 0.011) compared with patients who showed some degree of disability or who died.

CONCLUSIONS

Cerebrospinal fluid nimodipine concentrations measured during hospital drug infusion showed a correlation with long-term clinical outcome in patients with aneurysmal subarachnoid hemorrhage. These very preliminary data suggest that CSF concentrations monitoring may have some value in managing these patients.