Intravenous N-Acetylcysteine for the Treatment of Acute Ischemic Stroke

Overview

Stroke is a major cause of death and long-term disability in the developed world. While t-PA and mechanical thrombectomy have been shown to decrease disability in properly selected patients, many patients are left with lifelong symptoms. There are currently limited options available for patients who are not candidates for treatment with t-PA and/or mechanical thrombectomy. N-Acetylcysteine (NAC) is an FDA approved antioxidant and anti-inflammatory agent that has been used safely for many years in the treatment of acetaminophen overdose. In studies, the oral form has been shown to improve outcomes in acute ischemic stroke and has been shown to decrease the effects of ischemic brain injury in animal models. In a small human trial, it improved outcomes in patients suffering from mild traumatic brain injury (TBI). The intravenous formulation has a long safety record. It is not FDA approved for treating stroke but was reviewed by the FDA and was given an FDA IND for this study. The investigators propose a prospective randomized, double-blind, placebo-controlled study to evaluate the efficacy of administering intravenous N-acetylcysteine to patients with acute ischemic stroke. Eligible subjects will receive a commercially available form of intravenous NAC (Acetadote®) through for the first 21 hours following their enrollment. Patients enrolled who receive t-PA for thrombolysis will have their intravenous NAC infusion delayed for 24 hours after the completion of their t-PA infusion. Patients undergoing thrombectomy will be excluded from enrollment. Subjects will be evaluated by emergency department and/or division of neurology physicians at the time of enrollment, during their hospitalization, as well as 30 days and 90 days after enrollment. At each visit, subjects will be assessed for functional status and quality of life. This study is designed to compare the efficacy of intravenous N-acetylcysteine compared to normal treatment in patients with acute ischemic stroke.

Stroke is a leading cause of death and long-term disability in the United States, affecting more than 795,000 individuals annually. Of these, about 87% are ischemic strokes. In properly selected patients, intravenous recombinant tissue plasminogen activator (t-PA) has been shown to improve functional outcomes if given within 4.5 hours of the onset of stroke symptoms. Endovascular treatment both via clot retrieval devices and catheter directed t-PA has demonstrated benefit in well-selected patients with a large vessel occlusion and significant salvable tissue, also known as the penumbra. For patients who are not candidates for treatment with t-PA or mechanical thrombectomy, current treatment is centered on supportive care. N-Acetylcysteine (NAC) is an FDA approved medication that has been used successfully for many years in the treatment of acute acetaminophen overdose. It is generally well tolerated with the exception of rare anaphylactoid type reactions to the intravenous formulation. In mouse studies, N-acetylcysteine (NAC) has led to an increase in glutathione levels in the neurons along with a reduced number of microbleeds in ischemic models. NAC treated rats have been demonstrated to have increased level of glutathione in the astrocytes which provides a neuroprotective effect. This reduced the number of microbleeds and prevented further thrombosis or infarct . The efficacy of NAC by scavenging of ROS and increasing mitochondrial activities has been shown to reduce noise-induced hearing loss in chinchilla models. Another study on transient cerebral ischemia rat models defined a new pharmacokinetic in which the neuroprotective effects of NAC are mediated by the increased protein levels of hypoxia-induced factor 1 (HIF-1), its target erythropoietin (EPO) and glucose transporter (GLUT-3). Studies have shown consistent, similar results for ischemic brain injury in rat. Consistent human studies showing neuroprotective effects which lead to reduced symptoms after traumatic brain injury, reduced noise-induced hearing loss and as a treatment for Parkinson's disease. NAC has been shown to stimulate mitochondrial Complex 1 and 4 activities in vivo and in vitro in pre-synaptic terminals. The antioxidant effect of NAC by scavenging of ROS may prevent intracellular damage by inhibiting NF-kappaB, TNFalpha and Na+, K+ -ATPase inhibition of the neurons. In a human study of NAC for Parkinson's disease, NAC was found to mitigate the effects of ischemic brain injury in animal models. The antioxidant effect from repletion of intracellular glutathione is thought to preserve mitochondrial function and decrease cellular apoptosis. A placebo-controlled human trial demonstrated that NAC is able to decrease the effects of mild traumatic brain injury 7 days after blast injury. A recent study has shown that sufficient plasma and CSF levels can be achieved at well tolerated doses: 7 mg/kg, 35 mg/kg and 50 mg/kg. A recent randomized placebo-controlled trial demonstrated improvement in patients given oral N-acetylcysteine every four hours for a total of 72 hours after enrollment in their NIH stroke scale and modified Rankin Score at 90 days. Intravenous N-Acetylcysteine given over 21 hours has proven to be equally efficacious in the treatment of acetaminophen toxicity and is currently the standard of care for that indication. The investigators aim to determine if intravenous NAC completed over a 21-hour course will improve NIH Stroke Scale and modified Rankin scores at 90 days. of NAC following an acute ischemic stroke.