Efficacy of edaravone, a free radical scavenger, for the treatment of acute lacunar infarction

Edaravone for acute ischemic stroke - Systematic review with meta-analysis

INTRODUCTION

Ischemic stroke is a major cause of death and disability. Despite major advances in reperfusion therapies, most patients don´t benefit from these treatments as the time window for such interventions is limited. Therefore, other treatment options are desirable. Edaravone has been demonstrated in previous studies to reduce neurologic deficits in stroke patients.

OBJECTIVE

To test the hypothesis that edaravone reduces functional dependence in ischemic stroke patients.

MATERIAL AND METHODS

Systematic review and meta-analysis of randomized controlled trials and observational studies comparing edaravone to placebo in adult patients with ischemic stroke. The efficacy outcomes of interest were good and excellent functional outcomes at 90 days, defined as modified Rankin Scale (mRS) scores of 0-2 and 0-1 respectively. The safety outcomes of interest were intracranial hemorrhage and mortality.

RESULTS

19 studies were included. Edaravone treatment was associated with improved chances of 90-day good (OR=1.31, 95% CI 1.06-1.67) and excellent (OR=1.26, 95% CI 1.04-1.54) functional outcomes. Mortality was also lower in edaravone treated patients (OR=0.50, 95% CI 0.45-0.56). There were no differences in terms of intracranial hemorrhage. Most studies were observational and performed in Asian populations, especially Japan. Heterogeneity was high for all outcomes but reduced when analysis was restricted to randomized trials.

CONCLUSION

Edaravone is a promising treatment for ischemic stroke patients, with a more favorable time window. However, more randomized studies including patient populations outside Asia are required to confirm this hypothesis.

Human urinary kallidinogenase or edaravone combined with butylphthalide in the treatment of acute ischemic stroke

AIM

The effectiveness of neuroprotective agents is still unclear. Here we analyzed the clinical outcomes of acute ischemic stroke (AIS) patients treated with human urinary kallidinogenase (HUK) or edaravone (Eda) combined with butylphthalide (NBP).

METHODS

From January 2016 to December 2017, a total of 165 AIS patients were enrolled in this open-label, randomized controlled clinical study. Patients were randomly allocated into HUK group and Eda group in a ratio of 2:1. All the patients received basic treatments and NBP (200 mg p.o. qid) while HUK group received 0.15 PNA unit of HUK injection (ivgtt. qd) and Eda group received 30 mg Eda (ivgtt. bid) for 14 consecutive days. Independency rate [12-month modified Rankin Scale (mRS) score ≤ 1] and related factors were compared between the two groups.

RESULTS

Twelve-month mRS score of the HUK group (1, IQR 0~1) was significantly lower compared with Eda group (2, IQR 1~3, p < .0001). The HUK treatment achieved an independency rate of 79.1% while the Eda treatment only had 45.3% (p < .0001). Further binary logistic regression showed that recurrent stroke (RR: 0.1, 95% CI: 0.0~0.1, p = .038) and HUK treatment (RR: 4.2, 95% CI: 1.1~16.5, p = .041) could significantly affect patients' 12-month outcomes.

CONCLUSION

Human urinary kallidinogenase combined with NBP can enhance AIS patients' long-term independency rate, and the effectiveness of HUK combined therapy is better than Eda.

Clinical Effects of Early Edaravone Use in Acute Ischemic Stroke Patients Treated by Endovascular Reperfusion Therapy

Background and Purpose- Although several clinical studies suggested the beneficial effects of edaravone in acute ischemic stroke, most were performed under settings that differ from those in the current treatment strategy, which has dramatically changed with progress in reperfusion therapies. This study aimed to evaluate the efficacy of edaravone in patients with acute ischemic stroke treated by emergent endovascular reperfusion therapy. Methods- We conducted a retrospective observational study using a national administrative database. Patients with acute ischemic stroke treated by emergent endovascular reperfusion therapy were identified and dichotomized by whether edaravone was used within 2 days of admission. We compared the functional independence at hospital discharge, in-hospital mortality, and intracranial hemorrhage after admission between groups, adjusted by a well-validated case-mix adjustment model, in multivariate mixed-effect regression and propensity score matching analyses. Results- Of 11 508 patients eligible for analysis, 10 281 (89.3%) received edaravone therapy. The established risk adjustment model had good predictability for functional independence at hospital discharge, with an area under the receiver operating characteristic curve of 0.74. In the mixed-effect regression analysis, edaravone use was significantly associated with greater functional independence at hospital discharge (32.3% in the edaravone group versus 25.9% in the control group; adjusted odds ratio, 1.21; 95% confidence interval, 1.03-1.41), lower in-hospital mortality (9.9% in the edaravone group versus 17.4% in the control group; adjusted odds ratio, 0.52; 95% confidence interval, 0.43-0.62), and reduced intracranial hemorrhage after admission (1.4% in the edaravone group versus 2.7% in the control group; adjusted odds ratio, 0.55; 95% confidence interval, 0.37-0.82). Results of the propensity score matching analysis corroborated these results. Conclusions- This retrospective analysis of a Japanese nationwide administrative database suggested that combination therapy with edaravone and endovascular reperfusion therapy could be a promising therapeutic strategy in acute ischemic stroke. Further randomized control trials are warranted.

Edaravone and cyclosporine A as neuroprotective agents for acute ischemic stroke

It is well known that acute ischemic stroke (AIS) and subsequent reperfusion produce lethal levels of reactive oxygen species (ROS) in neuronal cells, which are generated in mitochondria. Mitochondrial ROS production is a self-amplifying process, termed "ROS-induced ROS release". Furthermore, the mitochondrial permeability transition pore (MPTP) is deeply involved in this process, and its opening could cause cell death. Edaravone, a free radical scavenger, is the only neuroprotective agent for AIS used in Japan. It captures and reduces excessive ROS, preventing brain damage. Cyclosporine A (CsA), an immunosuppressive agent, is a potential neuroprotective agent for AIS. It has been investigated that CsA prevents cellular death by suppressing MPTP opening. In this report, we will outline the actions of edaravone and CsA as neuroprotective agents in AIS, focusing on their relationship with ROS and MPTP.

Thrombosis, Neuroinflammation, and Poststroke Infection: The Multifaceted Role of Neutrophils in Stroke

Immune cells can significantly predict and affect the clinical outcome of stroke. In particular, the neutrophil-to-lymphocyte ratio was shown to predict hemorrhagic transformation and the clinical outcome of stroke; however, the immunological mechanisms underlying these effects are poorly understood. Neutrophils are the first cells to invade injured tissue following focal brain ischemia. In these conditions, their proinflammatory properties enhance tissue damage and may promote ischemic incidences by inducing thrombus formation. Therefore, they constitute a potential target for therapeutic approaches and prevention of stroke. Indeed, in animal models of focal brain ischemia, neutrophils have been targeted with successful results. However, even in brain lesions, neutrophils also exert beneficial effects, because they are involved in triggering immunological removal of cell debris. Furthermore, intact neutrophil function is essential for maintaining immunological defense against bacterial infections. Several studies have demonstrated that stroke-derived neutrophils displayed impaired bacterial defense capacity. Because infections are known to impair the clinical course of stroke, therapeutic interventions that target neutrophils should preserve or even restore their function outside the central nervous system (CNS). This complex situation requires well-tailored therapeutic approaches that can effectively tackle immune cell invasion in the brain but avoid increasing poststroke infections.

Targeting oxidative stress for the treatment of ischemic stroke: Upstream and downstream therapeutic strategies

Excessive oxygen and its chemical derivatives, namely reactive oxygen species (ROS), produce oxidative stress that has been known to lead to cell injury in ischemic stroke. ROS can damage macromolecules such as proteins and lipids and leads to cell autophagy, apoptosis, and necrosis to the cells. This review describes studies on the generation of ROS, its role in the pathogenesis of ischemic stroke, and recent development in therapeutic strategies in reducing oxidative stress after ischemic stroke.

Protective Effect of Edaravone on Glutamate-Induced Neurotoxicity in Spiral Ganglion Neurons

Glutamate is an important excitatory neurotransmitter in mammalian brains, but excessive amount of glutamate can cause “excitotoxicity” and lead to neuronal death. As bipolar neurons, spiral ganglion neurons (SGNs) function as a “bridge” in transmitting auditory information from the ear to the brain and can be damaged by excessive glutamate which results in sensorineural hearing loss. In this study, edaravone, a free radical scavenger, elicited both preventative and therapeutic effects on SGNs against glutamate-induced cell damage that was tested by MTT assay and trypan blue staining. Ho.33342 and PI double staining revealed that apoptosis as well as necrosis took place during glutamate treatment, and apoptosis was the main type of cell death. Oxidative stress played an important role in glutamate-induced cell damage but pretreatment with edaravone alleviated cell death. Results of western blot demonstrated that mechanisms underlying the toxicity of glutamate and the protection of edaravone were related to the PI3K pathway and Bcl-2 protein family.

Could edaravone prevent gentamicin ototoxicity? An experimental study

OBJECTIVES

Clinical application of gentamicin may cause nephrotoxicity and ototoxicity. Our study is the first study to investigate the protective effects of edaravone against the gentamicin-induced ototoxicity. We investigated the protective effect of intraperitoneal (i.p.) edaravone application against gentamicin-induced ototoxicity in guinea pigs.

METHODS

Fourteen guinea pigs were divided into two equal groups consisting of a control group and a study group. One-hundred sixty milligrams per kilogram subcutaneous gentamicin and 0.3 mL i.p. saline were applied simultaneously once daily to seven guinea pigs in the control group (group 1). One-hundred sixty milligrams per kilogram gentamicin was applied subcutaneously and 3 mg/kg edaravone was applied intraperitoneally once daily for 7 days simultaneously to seven guinea pigs in the study group (group 2). Following the drug application, auditory brainstem response measurements were performed for the left ear on the 3rd and 7th days.

RESULTS

Hearing threshold values of the group 1 and group 2 measured in the 3rd day of the study were detected as 57.14 ± 4.88 and 82.86 ± 7.56, respectively. This difference was statistically significant ( p < 0.05). Hearing threshold values of the group 1 and group 2 measured in the 7th day of the study were detected as 87.14 ± 4.88 and 62.86 ± 4.88, respectively. This difference was statistically significant ( p < 0.05).

CONCLUSION

A statistically significant difference between the average threshold values of edaravone-administered group 2 and that of group 1 without edaravone was found. These differences show that systemic edaravone administration could diminish ototoxic effects of gentamicin and the severity of the hearing loss.

Taming glutamate excitotoxicity: strategic pathway modulation for neuroprotection

Much work has been carried out in recent years showing that elevated glutamate levels in the extracellular environment of the central nervous system play a pivotal role in neurodegeneration in acute CNS injuries. With the elucidation of the mechanism governing glutamate excitotoxicity, researchers are devising therapeutic strategies to target different parts of the pathway which begins with glutamate accumulation and ultimately results in neuronal cell death. In this article, we review some of the major classes of agents that are currently being investigated and highlight some of the key studies for each. Glutamate scavenging is a relatively new approach that directly decreases glutamate levels in the brain, thus preventing excitotoxicity. Nitric oxide inhibitors and free radical scavengers are more well-studied strategies that continue to yield promising results.

Hemothorax after the intravenous administration of tissue plasminogen activator in a patient with acute ischemic stroke and rib fractures

A 79-year-old man experienced sudden-onset left hemiparesis and disturbance of consciousness. Diffusion-weighted magnetic resonance imaging showed an acute ischemic stroke in the territory of the right middle cerebral artery. He underwent systemic thrombolysis via the intravenous administration of tissue plasminogen activator (t-PA). Chest radiography and computed tomography performed the following day showed severe hemothorax with atelectasis of the left lung and multiple rib fractures; the initial chest radiogram had revealed rib fractures but we did not recognize them at the time. Conservative treatment with the placement of chest tubes was successful, and the patient recovered without further deterioration. Although systemic thrombolysis with t-PA is an accepted treatment for acute cerebral ischemic stroke, posttreatment intracranial hemorrhage has a negative effect on prognosis. Extracranial bleeding is a rare complication, and our search of the literature found no reports of hemothorax after treatment with t-PA in patients with cerebral ischemic stroke. We have reported a rare case of severe hemothorax after systemic thrombolysis with t-PA. This important complication indicates the need to rule out thoracic trauma with radiography and computed tomography of the chest.

Efficacy and safety of therapies for acute ischemic stroke in China: a network meta-analysis of 13289 patients from 145 randomized controlled trials

BACKGROUND

Many of these therapies have been compared against placebos, but have not been directly compared against each other. To evaluate the efficacy and safety of several commonly used drugs for AIS directly or indirectly.

METHODS

A systematic literature review was performed to identify randomized controlled trials (RCTs) published prior to April 2013 for AIS therapies. The primary outcome measures were the National Institutes of Health Stroke Scale (NIHSS) scores and the clinical effective rate. A fixed-effects meta-analysis and meta-regression are performed; lastly, performed a mixed treatment comparison was performed through the Bayesian methods.

RESULTS

Outcome of efficacy of therapies for acute ischemic stroke are as followed: All of the therapies mentioned above yielded results a more effective result than placebo, Sodium ozagrel (RR 3.86, 95%CI 3.18-4.61); Sodium ozagrel + edaravone (RR 9.60, 95%CI 7.04-13.06); Edaravone (RR 4.07, 95%CI 3.30-5.01); Edaravone + Kininogenase (RR 15.33, 95%CI 10.03-23.05). The significant difference in efficacy between edaravone monotherapy and Sodium ozagrel + edaravone was evident (RR 0.43, 95%CI 0.08-0.61) and was also significant between efficacy of edaravone + Kininogenase and Sodium ozagrel (RR 4.00, 95%CI 2.47-6.24). The differences between the risk and benefit were not significant when comparing Sodium ozagrel and edaravone or edaravone + Kininogenase and Sodium ozagrel + Edaravone for AIS. Outcome of the defect of neurological function: Placebo served a significant difference in treating the defects of neurological function compared with Sodium ozagrel (WMD = -3.11, 95%CI -4.43 to -1.79), Sodium ozagrel + edaravone (WMD = -6.25, 95%CI -7.96 to -4.54) and Edaravone + Kininogenase (WMD =  -3.47, 95%CI -5.73 to -1.21).

CONCLUSIONS

It provides that the efficacy of edaravone monotherapy in treatment was not more effective than Sodium ozagrel + edaravone.The efficacy of edaravone + Kininogenase monotherapy in treatment was more effective than Sodium ozagrel. Edaravone + Kininogenase and Sodium ozagrel + Edaravone appeared the most effective treatments. And Sodium ozagrel, Sodium ozagrel + edaravone, Edaravone + Kininogenase can improve the nerve dysfunction.

CeeTox™ Analysis of CNB-001 a Novel Curcumin-Based Neurotrophic/Neuroprotective Lead Compound to Treat Stroke: Comparison with NXY-059 and Radicut

In the present study, we used a comprehensive cellular toxicity (CeeTox) analysis panel to determine the toxicity profile for CNB-001 [4-((1E)-2-(5-(4-hydroxy-3-methoxystyryl-)-1-phenyl-1H-pyrazoyl-3-yl)vinyl)-2-methoxy-phenol)], which is a hybrid molecule created by combining cyclohexyl bisphenol A, a molecule with neurotrophic activity and curcumin, a spice with neuro-protective activity. CNB-001 is a lead development compound since we have recently shown that CNB-001 has significant preclinical efficacy both in vitro and in vivo. In this study, we compared the CeeTox profile of CNB-001 with two neuroprotective molecules that have been clinically tested for efficacy: the hydrophilic free radical spin trap agent NXY-059 and the hydrophobic free radical scavenger edaravone (Radicut). CeeTox analyses using a rat hepatoma cell line (H4IIE) resulted in estimated C(Tox) value (i.e., sustained concentration expected to produce toxicity in a rat 14-day repeat dose study) of 42 μM for CNB-001 compared with >300 μM for both NXY-059 and Radicut. The CeeTox panel suggests that CNB-001 produces some adverse effects on cellular adenosine triphosphate content, membrane toxicity, glutathione content, and cell mass (or number), but only with high concentrations of the drug. After a 24-h exposure, the drug concentration that produced a half-maximal response (TC(50)) on the measures noted above ranges from 55 to 193 μM. Moreover, all CNB-001-induced changes in the markers were coincident with loss of cell number, prior to acute cell death as measured by membrane integrity, suggesting a cytostatic effect of CNB-001. NXY-059 and Radicut did not have acute toxic effects on H4IIE cells. We also found that CNB-001 resulted in an inhibition of ethoxyresorufin-o-deethylase activity, indicating that the drug may affect cytochrome P4501A activity and that CNB-001 was metabolically unstable using a rat microsome assay system. For CNB-001, an estimated in vitro efficacy/toxicity ratio is 183-643-fold, suggesting that there is a significant therapeutic safety window for CNB-001 and that it should be further developed as a novel neuroprotective agent to treat stroke.

Anterior cerebral artery dissection presenting subarachnoid hemorrhage and cerebral infarction

A 35-year-old man presented with simultaneous occurrence of subarachnoid hemorrhage (SAH) and cerebral infarction (CI) caused by anterior cerebral artery (ACA) dissection. He complained of sudden onset of left frontal headache and his symptoms progressed to consciousness disturbance and right hemiparesis. Computed tomography and magnetic resonance imaging demonstrated SAH localized in the left interhemispheric fissure and CI in the territory of the left ACA. Right carotid angiography demonstrated a long double lumen sign at the left A2 to A4 segment of the left ACA, leading to a diagnosis of the combined type of CI and SAH caused by ACA dissection. Although many surgeons have previously tried to perform endovascular treatment, we selected only medication in this case, and his neurological findings gradually improved. Only 9 cases including the present case presented with simultaneous occurrence of SAH and CI caused by ACA dissection. Many of these patients showed stenosis with dilatation of ACA on carotid angiography. The prognoses of these patients were good. However, many SAH patients with dissecting aneurysm had poor prognoses. To improve the strategy for managing ACA dissection, we need to accumulate a greater number of such cases in the future. We also recommend that angiography should be performed in the patients with ACA dissection.

Effects of edaravone, a free radical scavenger, on photochemically induced cerebral infarction in a rat hemiplegic model

Edaravone is a free radical scavenger that protects the adjacent cortex during cerebral infarction. We created a hemiparetic model of cerebral thrombosis from a photochemically induced infarction with the photosensitive dye, rose bengal, in rats. We examined the effects of edaravone on recovery in the model. A total of 36 adult Wistar rats were used. The right sensorimotor area was irradiated with green light with a wavelength of 533 nm (10 mm diameter), and the rose bengal was injected intravenously to create an infarction. The edaravone group was injected intraperitoneally with edaravone (3 mg/kg), and the control group was injected with saline. The recovery process of the hemiplegia was evaluated with the 7-step scale of Fenny. The infarcted areas were measured after fixation. The recovery of the paralysis in the edaravone-treated group was significantly earlier than that in the untreated group. Seven days later, both groups were mostly recovered and had scores of 7, and the infarction region was significantly smaller in the edaravone-treated group. Edaravone reduced the infarction area and promoted the functional recovery of hemiparesis from cerebral thrombosis in a rat model. These findings suggest that edaravone treatment would be effective in clinical patients recovering from cerebral infarction.

Protective effects of edaravone against cisplatin-induced hair cell damage in zebrafish

OBJECTIVE

Edaravone is known to have a potent free radical scavenging effect. The objective of the present study was to evaluate the effects of edaravone on cisplatin-induced ototoxicity in transgenic zebrafish (Brn3C: EGFP).

METHODS

Five day post-fertilization zebrafish larvae were exposed to 1000 μM cisplatin and 50 μM, 100 μM, 250 μM, 500 μM, 750 μM, and 1000 μM concentrations of edaravone for 4h. Hair cells within neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed by fluorescence microscopy and confocal microscopy (n=10). Hair cell survival was calculated as a percentage of the hair cells in the control group that were not exposed to cisplatin. Ultrastructural changes were evaluated using scanning electron microscopy and transmission electron microscopy.

RESULTS

Edaravone protected cisplatin-induced hair cell loss of neuromasts (edaravone 750 μM: 8.7 ± 1.5 cells, cisplatin 1000 μM only: 3.7 ± 0.9 cells; n=10, p<0.0001) and decreased the Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) reaction. Structures of mitochondria and hair cell within neuromasts in ultrastructural analysis were preserved in zebrafish exposed to 1000 μM cisplatin and 750 μM edaravone for 4h.

CONCLUSIONS

Edaravone attenuated cisplatin-induced hair cell damage in zebrafish. The results of the current study suggest that cisplatin induces apoptosis, and the apoptotic cell death can be prevented by treatment with edaravone in zebrafish.

Effects of edaravone on amyloid-β precursor protein processing in SY5Y-APP695 cells

Previous reports have revealed that reactive oxygen species (ROS) is involved in the development of Alzheimer's disease (AD), and recent studies indicate that free radical-generating systems can regulate amyloid-β precursor protein (APP) processing. Edaravone is a novel free radical scavenger currently used to reduce cerebral damages after acute cerebral infarction. In the present study, we used SH-SY5Y cells stably transfected with the human "Swedish" APP mutation APP695 (SY5Y-APP695swe) as an in vitro model to investigate the effect of edaravone on APP processing. The result showed that edaravone treatment for 24 h down-regulated β-amyloid (Aβ) production in a dose-dependent manner. Moreover, edaravone modulated APP processing by increasing α-secretase-derived APP fragments and decreasing β-secretase-derived APP fragments. In addition, the mRNA and protein levels of insulin degrading enzyme (IDE) and neprilysin (NEP), two key Aβ degrading enzymes, were not changed after edaravone administration. Taken together, our data suggested that edaravone played an important role in regulating Aβ production by enhancing the non-amyloidogenic pathway and inhibiting the amyloidogenic pathway. Thus, edaravone may be potentially useful for treating Alzheimer's disease (AD).

A randomized controlled clinical trial to compare the safety and efficacy of edaravone in acute ischemic stroke

Background and Objective:

Edaravone has potent antioxidant and free radical scavenger properties. Few Japanese studies had demonstrated its neuroprotective role in acute ischemic stroke (AIS). This study aims to evaluate the efficacy of edaravone in terms of functional outcome in a group of Indian patients of AIS.

Materials and Methods:

Fifty patients of AIS were randomly divided into two groups. The study group received 30 mg of edaravone twice daily for 14 days by infusion, while control group received normal saline infusion as placebo. Outcome assessment was done by the Modified Rankin Scale (MRS). MRS score ≤2 at 90 days was considered as a favorable outcome.

Results:

Of 25 patients, 18 (72%) had favorable outcomes (MRS ≤2) at 90 days in edaravone group, while 10 (40%) of 25 patients in placebo group had favorable outcome (P < 0.005). Two patients expired (one in each group) during treatment. The mean Barthel index increased from 41.20 ± 32.70 at baseline to 82.40 ± 18.32 at day 90 in edaravone group as compared with placebo group in which scores were 44.20 ± 22.76 at baseline and 68.20 ± 21.30 at day 90 (P < 0.005).

Conclusions:

We therefore conclude that edaravone effectively improves functional outcome in AIS.

Edaravone alleviates delayed neuronal death and long-dated cognitive dysfunction of hippocampus after transient focal ischemia in Wistar rat brains

Edaravone is currently being used in acute ischemic stroke both in clinical and experimental research as a potent antioxidant. Here we explore the effects of edaravone on delayed neuronal death (DND) and long-dated cognitive dysfunction of hippocampus after cerebral ischemia-reperfusion (IR) injury and explain the underlying mechanisms and pathways. Our findings suggested that edaravone not only significantly alleviated delayed neuronal death and cognitive dysfunction of hippocampus after cerebral focal ischemia, but also markedly decreased malondialdehyde (MDA) levels. In addition, edaravone increased superoxide dismutase (SOD) levels and reduced the levels of inflammatory cytokines such as IL-1β and TNF-α expression; edaravone, also suppressed glial fibrillary acidic protein (GFAP) proliferation at days 3, 7 and 30 after reperfusion. Overall, the consensus emerging from this body of data indicated that edaravone exerts a later neuroprotective effect to hippocampus through its ability to inhibit inflammation, suppression of astrocyte activation and scavenging free radicals in stroke events.

A critical assessment of edaravone acute ischemic stroke efficacy trials: is edaravone an effective neuroprotective therapy?

IMPORTANCE OF THE FIELD

Edaravone (Radicut) is a free radical scavenger marketed in Japan by Mitsubishi Tanabe Pharma Corp. to treat acute ischemic stroke (AIS) patients presenting within 24 h of the attack. Injectable edaravone ampoules (30 mg b.i.d., i.v., 14 days) were first approved on 23 May 2001. On 19 January 2010, as a new innovation, the Radicut BAG (Intravenous BAG) was approved by the Japanese Ministry of Health and Welfare. Efficacy of edaravone ranges from large significant clinical improvements to only modest improvements in clinical function measured using standard stroke scales when administered 6-72 h following an ischemic stroke. With almost 17 years of edaravone clinical experience, a few adverse events--including acute renal failure--have been noted.

WHAT THE READER WILL GAIN

This is the only article to date to critically review available clinical efficacy and toxicology data published in the literature to ascertain whether edaravone should be further pursued as a candidate for development worldwide.

AREAS COVERED IN THIS REVIEW

This review covers clinical studies carried out over the period 1993-2008.

TAKE HOME MESSAGE

Edaravone may be a useful neuroprotective agent to treat the > 15 million victims worldwide who are devastated by stroke annually. Additional clinical studies are necessary to verify the efficacy of edaravone.

Translational stroke research using a rabbit embolic stroke model: a correlative analysis hypothesis for novel therapy development

Alteplase (tissue plasminogen activator, tPA) is currently the only FDA-approved treatment that can be given to acute ischemic stroke (AIS) patients if patients present within 3 h of an ischemic stroke. After 14 years of alteplase clinical research, evidence now suggests that the therapeutic treatment window can be expanded 4.5 h, but this is not formally approved by the FDA. Even though there remains a significant risk of intracerebral hemorrhage associated with alteplase administration, there is an increased chance of favorable outcome with tPA treatment. Over the last 30 years, the use of preclinical models has assisted with the search for new effective treatments for stroke, but there has been difficulty with the translation of efficacy from animals to humans. Current research focuses on the development of new and potentially useful thrombolytics, neuroprotective agents, and devices which are also being tested for efficacy in preclinical and clinical trials. One model in particular, the rabbit small clot embolic stroke model (RSCEM) which was developed to test tPA for efficacy, remains the only preclinical model used to gain FDA approval of a therapeutic for stroke. Correlative analyses from existing preclinical translational studies and clinical trials indicate that there is a therapeutic window ratio (ARR) of 2.43-3 between the RSCEM and AIS patients. In conclusion, the RSCEM can be used as an effective translational tool to gauge the clinical potential of new treatments.

Edaravone improves the expression of nerve growth factor in human astrocytes subjected to hypoxia/reoxygenation

Edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, is known to ameliorate postischemic neuronal dysfunction. Nerve growth factor (NGF) is essential for neuronal growth and survival. We have addressed the effect of edaravone on the NGF expression in astrocytes exposed to hypoxia/reoxygenation. Normal human astrocytes in culture were incubated under hypoxia for 3h and then treated with edaravone under normal culture condition for up to 72h. The levels of NGF mRNA were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) or real-time quantitative PCR and NGF protein levels were measured by enzyme-linked immunosorbent assay (ELISA). Edaravone enhanced, in time- and concentration-dependent manners, the expressions of NGF mRNA and protein in astrocytes under reoxygenation condition. After the treatment for 72h, 1mmol/L edaravone enhanced the levels of NGF protein in astrocyte-conditioned media by 1.7-fold of the control. An inhibitor of c-Jun N-terminal kinase (JNK) suppressed the effect of edaravone on the NGF expression, and cellular levels of phospho-JNK were increased in response to edaravone. We conclude that edaravone enhances, via the JNK pathway, NGF expression in astrocytes. This agent may exert a neurotrophic effect in the therapy of brain injury in ischemia/reperfusion.

Protective effects of the free radical scavenger edaravone against glutamate neurotoxicity in nearly pure neuronal culture

PURPOSE

Edaravone, a free radical scavenger, has shown neuroprotection in both animals and humans. To evaluate the mechanism of this protection, we examined the effect of edaravone on neurons themselves against glutamate neurotoxicity.

METHODS

Neurons were collected from 18-day fetal rat brains and a culture of almost pure neurons was obtained after 14-day culture. The neurons were exposed to 50 muM glutamate for 10 min, followed by normal culture for 24 h. Edaravone was added to the medium during the glutamate insult (prophylactic effect) or after the insult (treatment effect). First, the cell survival rate was measured by staining with trypan blue. Second, the cells were stained with 6-carboxy-2', 7'-dichlorodihydrofluorescein diacetate, di-(acetoxymethyl ester) (C-DCDHF-DA) and the relative amount of reactive oxygen species (ROS) was measured by flow cytometry. Third, the cells were stained with Hoechst 33342 and propidium iodide and the numbers of apoptotic and necrotic cells were counted.

RESULTS

A dose-dependent prophylactic effect was observed and the cell survival rate in 500 muM edaravone was significantly higher than that without it. However, there was no treatment effect beyond 2 h after the insult. The amount of ROS under 500 muM edaravone at 4 h after the glutamate insult was significantly lower than the control amount. Necrosis, but not apoptosis, was significantly inhibited by edaravone.

CONCLUSION

Edaravone mainly showed a prophylactic effect on neurons against glutamate neurotoxicity, possibly through the inhibition of necrosis via the suppression of ROS production. However, for a protective effect, a higher, supraclinical concentration was required, compared to the concentrations producing a protective effect in glial and endothelial cells in previous studies.

Edaravone for the treatment of acute cerebral infarction: role of endothelium-derived nitric oxide and oxidative stress

Thrombolytic therapy is the most effective therapeutic strategy for the prevention of brain injury and reduction of mortality in patients with acute cerebral infarction. A combination of established thrombolytic therapy and effective neuronal protection therapy has more beneficial effects for patients with acute cerebral infarction. Edaravone (chemical name: 3-methyl-1-phenyl-2-pyrazolin-5-one) is a strong, novel scavenger of free radicals. Several lines of evidence have shown that edaravone has preventive effects on brain injury following ischaemia and reperfusion in patients with brain attack. This review focuses on putative mechanisms underlying the beneficial effects of edaravone on the atherosclerotic process in patients with stroke and on the possibility of edaravone-induced extension of the therapeutic time window in patients with acute cerebral infarction.

Administration of free radical scavenger edaravone associated with higher frequency of hemorrhagic transformation in patients with cardiogenic embolism

Free radicals are known to activate coagulation and inhibit fibrinolysis. Edaravone, a free radical scavenger, protects vascular endothelial cells and neurons during acute brain ischemia in in vitro models. Hemorrhagic transformation and treatment outcomes were retrospectively examined in 76 patients with acute cardiogenic embolism treated with edaravone in addition to routine treatment within 24 hours of the onset of symptoms. Hemorrhagic transformation was categorized according to European Cooperative Acute Stroke Study-II. Patient characteristics were also evaluated, including evidence of hypertension, diabetes mellitus, hyperlipidemia, coronary heart disease, history of smoking, National Institutes of Health Stroke Scale on arrival, and modified Rankin scale at 3 months post-onset. Edaravone administration was one of the factors that contributed to increased frequency of hemorrhagic transformation, but had showed no significant relationship with the outcome. The present study showed that edaravone administration increased the frequency of hemorrhagic transformation with heparin in patients with cardiogenic embolism. Free radical scavenging may have promoted the coagulating conditions. Edaravone administration may allow reduction of the dose of heparin and tissue plasminogen activator in patients with acute ischemic stroke.

Efficacy of the free radical scavenger, edaravone, for motor palsy of acute lacunar infarction

OBJECTIVE

Free radicals are important in causing neural cell injury during cerebral infarction. Although there was a randomized, placebo-controlled, double-blind study at multiple centers in Japan showing the efficacy of the free radical scavenger, edaravone, in acute cerebral infarction, to date the clinical studies are few. This study investigated the effect of edaravone on the outcome of patients with acute lacunar infarction.

METHODS

We retrospectively evaluated 124 consecutive patients with first-ever acute lacunar infarctions who were admitted to our hospital within 24 hours after the onset between January 2004 and June 2007. Of these, 59 patients received both edaravone and conventional therapy (edaravone group), and the other 65 underwent conventional therapy only (non-edaravone group). There was no significant difference in patients' baseline characteristics in the two groups. The clinical outcome was assessed by the National Institutes of Health Stroke Scale (NIHSS).

RESULTS

The reduction of NIHSS scale during hospitalization (1.5+/-1.0 vs. 1.0+/-1.1; p = 0.007), especially that of the motor palsy scale (1.0+/-1.0 vs. 0.5+/-1.0; p = 0.006) was significantly larger, and the percentage of patients with a favorable outcome (NIHSS at discharge < or =1) (91.5% vs. 78.5%; p = 0.044) was significantly better in the edaravone group.

CONCLUSION

Edaravone improves the outcomes of patients with acute lacunar infarction, especially motor palsy, without regard to the conventional therapy performed concomitantly.

Protective effect of edaravone against tobramycin-induced ototoxicity

CONCLUSION

It is suggested that simultaneous treatment with the radical scavenger edaravone has an effective protective effect against tobramycin ototoxicity in rat. Even if the edaravone treatment is postponed for 7 days, it can still prevent hearing loss, but a 14 day delay cannot protect from ototoxicity.

OBJECTIVES

With the aim of alleviating hearing loss caused by aminoglycoside ototoxicity, we performed a trial to assess the hearing protective efficacy of the radical scavenger edaravone.

MATERIALS AND METHODS

In part one of the study, 21 male Sprague-Dawley albino rats were used; 2 rats served as controls for the safety of edaravone. Eight rats each received 10 subcutaneous injections (s.c.) of tobramycin (160 mg/kg b.w.) once daily and saline injection intraperitoneally for 2 weeks. Eleven rats were given 10 s.c. tobramycin injections simultaneously with an intraperitoneal injection of edaravone (3 mg/kg b.w.). In part two, tobramycin was injected in 13 rats (as above). Five of these received two edaravone injections 7 days later and four rats similarly 14 days later. Auditory brainstem response (ABR) was used to assess hearing.

RESULTS

All rats treated only with tobramycin showed a deterioration of hearing. None of the rats given simultaneous treatment with tobramycin and edaravone demonstrated hearing loss. A 7 day delay in edaravone injection still prevented hearing loss, but a 14 day delay had only a temporary prophylactic effect.

A case report of acute renal failure and fulminant hepatitis associated with edaravone administration in a cerebral infarction patient

A 60-year-old male with cerebral infarction was admitted to our hospital and treated with edaravone. On day 12 of hospitalization, he suddenly lost consciousness and went into shock. Based on the laboratory findings, acute renal failure (ARF), fulminant hepatitis, and disseminated intravascular coagulation (DIC) were diagnosed. We immediately initiated continuous hemodiafiltration for three days and performed three sessions of plasma exchange. Following this, a gradual improvement was observed in the patient's general condition and laboratory values. On day 17 of hospitalization, intermittent hemodialysis (HD) was initiated. On day 20 of hospitalization, his renal function started to improve with an increase in urine volume. HD was successfully discontinued on the same day. Although the drug lymphocyte stimulation test for edaravone was negative, edaravone-induced fulminant hepatitis was suggested based on liver biopsy findings. We present a case of ARF, fulminant hepatitis, and DIC due to edaravone administration that was successfully treated with blood purification techniques. Since the use of edaravone treatment is expected to increase in the future, it is essential that clinicians consider the potential adverse effects of this treatment. It is suggested that blood purification is effective in inducing remission in patients with complications due to edaravone treatment.

Free radical scavenger edaravone suppresses x-ray-induced apoptosis through p53 inhibition in MOLT-4 cells

Edaravone, a clinical drug used widely for the treatment of acute cerebral infarction, is reported to scavenge free radicals. In the present study, we investigated the radioprotective effect of edaravone on X-ray-induced apoptosis in MOLT-4 cells. Apoptosis was determined by the dye exclusion test, Annexin V binding assay, cleavage of caspase, and DNA fragmentation. We found that edaravone significantly suppressed the X-ray-induced apoptosis. The amount of intracellular ROS production was determined by the chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate system. We found that the intracellular ROS production by X-irradiation was completely suppressed by the addition of edaravone. The accumulation and phosphorylation of p53 and the expression of p21(WAF1), a target protein of p53, which were induced by X-irradiation, were also suppressed by adding edaravone. We conclude that the free radical scavenger edaravone suppresses X-ray-induced apoptosis in MOLT-4 cells by inhibiting p53.

Edaravone inhibits the expression of vascular endothelial growth factor in human astrocytes exposed to hypoxia

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, reduces brain edema in patients with acute ischemic stroke. We have addressed the effect of edaravone on the expression of vascular endothelial growth factor (VEGF), a potential mediator of brain edema, in astrocytes exposed to hypoxia. Normal human astrocytes in culture were treated with edaravone, and the levels of VEGF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative PCR and enzyme-linked immunosorbent assay (ELISA). The expression of hypoxia-inducible factor-1alpha (HIF-1alpha), a transcriptional activator of VEGF, was examined by RT-PCR, real-time PCR and western blotting; and the binding of HIF-1alpha to the promoter region of VEGF gene by chromatin immunoprecipitation (ChIP) assay. Edaravone moderately suppressed the expression of VEGF mRNA and protein in astrocytes under hypoxia in time- and concentration-dependent manners. It also suppressed the accumulation of HIF-1alpha in the nuclei under hypoxia. ChIP assay confirmed that edaravone reduced HIF-1alpha binding to VEGF promoter. We conclude that edaravone inhibits VEGF expression in astrocytes exposed to hypoxia, at least partly, through the down-regulation of HIF-1alpha. These findings offer a partial explanation for the protective effect of edaravone on the development of brain edema in patients with acute ischemic stroke.