Acetaminophen in aSAH to Inhibit Lipid Peroxidation and Cerebral Vasospasm

Inclusion Criteria: * Ages ≥ 20 * Fisher Grade III or III + IV SAH based upon admitting CT scan * Aneurysm secured by either clipping or coiling within 72 hours of SAH * Intracranial aneurysm confirmed by angiography or CTA * Presence of ventriculostomy for external ventricular drainage (EVD) prior to randomization Exclusion Criteria: * Consent unobtainable * Enrollment in another interventional study * Patient is pregnant or lactating * Known co-morbidities that could affect outcome of this study * Contraindication to CTA * Serum creatinine \> 1.4 * Documented allergy to iodinated contrast that cannot be adequately treated with premedication * Documented allergy and/or intolerance to ApAP * Baseline liver disease * History of recent alcohol abuse with documented ALT or AST above normal laboratory values * Documented history of both malnutrition and decreased serum albumin below normal lab values * Documented abnormal platelet count below normal lab values * Documented abnormal PT or PTT above normal lab values * History or evidence of active asthma * Documented allergy and/or intolerance to N-acetylcysteine * Currently taking phenytoin, carbamazepine, or phenobarbital * Currently taking isoniazid (INH, Lanzid, Nydrazid) * Severe life-threatening complications resulting from standard aneurysm treatments that will likely prevent completion of the study * Patient unsuitable for the study, in the opinion of the investigator(s)