Treatment of cerebral vasospasm with biocompatible controlled-release systems for intracranial drug delivery

Nicardipine Loaded Solid Phospholipid Extrudates for the Prevention of Cerebral Vasospasms: In Vitro Characterization

The aim of the study was to develop nicardipine loaded phospholipid extrudates as an alternative for PLA/PLGA-based implants for the prevention of cerebral vasospasms. Extrudates of different mixtures of saturated and unsaturated phosphatidylcholine (PC) were produced and characterized by DSC, microscopy and texture analysis. Single phospholipid components were identified by ELSD-HPLC. Extrudates of 2 mm diameter were obtained by twin screw extrusion temperatures below 50 °C. The ratio of unsaturated and saturated phosphatidylcholine components determines the physicochemical properties of the extrudates as well as the rate of erosion. Nicardipine loaded phospholipids extrudates released the drug over several weeks in vitro. The phospholipid composition of the remaining extrudate changed during the release, the content of unsaturated phospholipids decreased faster compared to the saturated ones. In conclusion, solid phospholipid extrudates are promising materials for the development of new parenteral controlled release systems.

In Premature Newborns Intraventricular Hemorrhage Causes Cerebral Vasospasm and Associated Neurodisability via Heme-Induced Inflammasome-Mediated Interleukin-1 Production and Nitric Oxide Depletion

BACKGROUND

Intraventricular hemorrhage (IVH) occurs in 60-70% of neonates weighing 500-750 g and 10-20% of those weighing 1,000-1,500 g. All forms of IVH have been associated with neurocognitive deficits. Both subarachnoid and IVHs have been associated with delayed vasospasm leading to neurological deficits. Pathways linking hemoglobin release from blood clots to vasospasm include heme-induced activation of inflammasomes releasing interleukin-1 (IL-1) that can cause calcium dependent and independent vasospasm. Free hemoglobin is a potent scavenger of nitric oxide (NO). Depletion of NO, a potent endogenous vasodilator, has been associated with features of vasospasm.

HYPOTHESIS

In premature newborns, IVH causes cerebral vasospasm and associated neurodisability via heme-induced increased inflammasome-mediated IL-1 production and NO depletion.

CONFIRMATION OF HYPOTHESIS AND IMPLICATIONS

This hypothesis could be confirmed in the IVH animal model with visualization of any associated vasospasm by angiography and in newborns with IVH by transcranial Doppler ultrasonography and correlation with cerebrospinal fluid IL-1 and NO metabolite levels. Confirmation of the role of heme in activation of inflammasomes causing IL-1 production and NO binding could be achieved by measuring the effect of heme scavenging interventions on IL-1 levels and levels of NO metabolites. In addition to removal of the accumulated blood of an IVH by drainage, irrigation, and fibrinolytic therapy intrathecal application of vasodilators and heme scavenging agents like haptoglobin and haemopexin and systemic treatment with inhibitors of inflammasomes like telmisartan could be used to prevent and treat cerebral vasospasm, and thus reduce the risk of associated brain injury in premature neonates.

The Role of Neurogenic Inflammation in Blood-Brain Barrier Disruption and Development of Cerebral Oedema Following Acute Central Nervous System (CNS) Injury

Acute central nervous system (CNS) injury, encompassing traumatic brain injury (TBI) and stroke, accounts for a significant burden of morbidity and mortality worldwide, largely attributable to the development of cerebral oedema and elevated intracranial pressure (ICP). Despite this, clinical treatments are limited and new therapies are urgently required to improve patient outcomes and survival. Originally characterised in peripheral tissues, such as the skin and lungs as a neurally-elicited inflammatory process that contributes to increased microvascular permeability and tissue swelling, neurogenic inflammation has now been described in acute injury to the brain where it may play a key role in the secondary injury cascades that evolve following both TBI and stroke. In particular, release of the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) appear to be critically involved. In particular, increased SP expression is observed in perivascular tissue following acute CNS injury, with the magnitude of SP release being related to both the frequency and degree of the insult. SP release is associated with profound blood-brain barrier disruption and the subsequent development of vasogenic oedema, as well as neuronal injury and poor functional outcomes. Inhibition of SP through use of a neurokinin 1 (NK1) antagonist is highly beneficial following both TBI and ischaemic stroke in pre-clinical models. The role of CGRP is more unclear, especially with respect to TBI, with both elevations and reductions in CGRP levels reported following trauma. However, a beneficial role has been delineated in stroke, given its potent vasodilatory effects. Thus, modulating neuropeptides represents a novel therapeutic target in the treatment of cerebral oedema following acute CNS injury.

A Site-Specific, Sustained-Release Drug Delivery System for Aneurysmal Subarachnoid Hemorrhage

Nimodipine is the only drug approved for use by the Food and Drug Administration for improving outcome after aneurysmal subarachnoid hemorrhage (SAH). It has less than optimal efficacy, causes dose-limiting hypotension in a substantial proportion of patients, and is administered enterally 6 times daily. We describe development of site-specific, sustained-release nimodipine microparticles that can be delivered once directly into the subarachnoid space or cerebral ventricles for potential improvement in outcome of patients with aneurysmal SAH. Eight injectable microparticle formulations of nimodipine in poly(DL-lactide-co-glycolide) (PLGA) polymers of varying composition were tested in vitro, and 1 was advanced into preclinical studies and clinical application. Intracisternal or intraventricular injection of nimodipine-PLGA microparticles in rats and beagles demonstrated dose-dependent, sustained concentrations of nimodipine in plasma and cerebrospinal fluid for up to 29 days with minimal toxicity in the brain or systemic tissues at doses <2 mg in rats and 51 mg in beagles, which would be equivalent of up to 612-1200 mg in humans, based on scaling relative to cerebrospinal fluid volumes. Efficacy was tested in the double-hemorrhage dog model of SAH. Nimodipine-PLGA microparticles significantly attenuated angiographic vasospasm. This therapeutic approach shows promise for improving outcome after SAH and may have broader applicability for similar diseases that are confined to body cavities or spaces, are self-limited, and lack effective treatments.

Aneurysmal subarachnoid hemorrhage: pathobiology, current treatment and future directions

Aneurysmal subarachnoid hemorrhage is the most devastating form of stroke. Many pathological mechanisms ensue after cerebral aneurysm rupture, including hydrocephalus, apoptosis of endothelial cells and neurons, cerebral edema, loss of blood-brain barrier, abnormal cerebral autoregulation, microthrombosis, cortical spreading depolarization and macrovascular vasospasm. Although studied extensively through experimental and clinical trials, current treatment guidelines to prevent delayed cerebral ischemia is limited to oral nimodipine, maintenance of euvolemia, induction of hypertension if ischemic signs occur and endovascular therapy for patients with continued ischemia after induced hypertension. Future investigations will involve agents targeting vasodilation, anticoagulation, inhibition of apoptosis pathways, free radical neutralization, suppression of cortical spreading depolarization and attenuation of inflammation.

Synthesis and therapeutic applications of biocompatible or biodegradable hyperbranched polymers

The recent progress in the synthesis, modifications and therapeutic applications of biocompatible or biodegradable hyperbranched polymers has been reviewed.

Fasudil improves short-term echocardiographic parameters of diastolic function in patients with type 2 diabetes with preserved left ventricular ejection fraction: a pilot study

Left ventricular (LV) diastolic dysfunction is observed frequently in patients with type 2 diabetes; however, few studies have focused on the effect of the Rho-associated kinase inhibitor fasudil on cardiac performance in humans. We conducted a prospective pilot study to assess the impact of fasudil on LV diastolic function in patients with diabetes without systolic dysfunction. Two hundred and fifty eligible patients with type 2 diabetes (149 men [61.3 %] and 94 women [38.7 %]) with a mean age of 57.2 years were randomly assigned to fasudil (n = 122, 30 mg intravenously twice a day for 14 days) or placebo (n = 121) groups. Echocardiographic variables were measured at the baseline and 1 month after the intervention. Compared with the placebo group, the fasudil group showed a significant decrease in diastolic blood pressure and in the peak of late diastolic transmitral flow (Am) (P < 0.05 for both). Deceleration time (DT), isovolumic relaxation time (IVRT), the peak of early diastolic annular velocity (e'), the peak of late diastolic annular velocity, and E/e' also exhibited a significant improvement (all, P < 0.05) after fasudil administration. Furthermore, the Em/Am ratio and IVRT, DT, and E/e' values recorded after fasudil treatment in the subgroup with impaired LV relaxation significantly differed from the corresponding values in the subgroup with normal LV relaxation (all, P < 0.05). Fasudil improves short-term echocardiographic parameters of LV diastolic function in patients with type 2 diabetes with preserved left ventricular ejection fraction.

Current management of delayed cerebral ischemia: update from results of recent clinical trials

Subarachnoid hemorrhage (SAH) accounts for 5-7% of all strokes worldwide and is associated with high mortality and morbidity. Even after surgical intervention, approximately 30% of patients develop long-term cognitive and neurological deficits that significantly affect their capacity to return to work or daily life unassisted. Much of this stems from a secondary ischemic phenomenon referred to as delayed cerebral ischemia (DCI). While DCI has been historically attributed to the narrowing of the large basal cerebral arteries, it is now recognized that numerous pathways contribute to its pathogenesis, including microcirculatory dysfunction, microthrombosis, cortical spreading depression, and early brain injury. This paper seeks to summarize some of the key pathophysiological events that are associated with poor outcome after SAH, provide a general overview of current methods of treating SAH patients, and review the results of recent clinical trials directed at improving outcome after SAH. The scientific basis of these studies will be discussed, in addition to the available results and recommendations for effective patient management. Therapeutic methods under current clinical investigation will also be addressed. In particular, the mechanisms by which they are expected to elicit improved outcome will be investigated, as well as the specific study designs and anticipated time lines for completion.

Delayed neurological deterioration after subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) causes early brain injury (EBI) that is mediated by effects of transient cerebral ischaemia during bleeding plus effects of the subarachnoid blood. Secondary effects of SAH include increased intracranial pressure, destruction of brain tissue by intracerebral haemorrhage, brain shift, and herniation, all of which contribute to pathology. Many patients survive these phenomena, but deteriorate days later from delayed cerebral ischaemia (DCI), which causes poor outcome or death in up to 30% of patients with SAH. DCI is thought to be caused by the combined effects of angiographic vasospasm, arteriolar constriction and thrombosis, cortical spreading ischaemia, and processes triggered by EBI. Treatment for DCI includes prophylactic administration of nimodipine, and current neurointensive care. Prompt recognition of DCI and immediate treatment by means of induced hypertension and balloon or pharmacological angioplasty are considered important by many physicians, although the evidence to support such approaches is limited. This Review summarizes the pathophysiology of DCI after SAH and discusses established treatments for this condition. Novel strategies--including drugs such as statins, sodium nitrite, albumin, dantrolene, cilostazol, and intracranial delivery of nimodipine or magnesium--are also discussed.

The protective effect of fasudil on the structure and function of cardiac mitochondria from rats with type 2 diabetes induced by streptozotocin with a high-fat diet is mediated by the attenuation of oxidative stress

Dysfunction of cardiac mitochondria appears to play a substantial role in cardiomyopathy or myocardial dysfunction and is a promising therapeutic target for many cardiovascular diseases. We investigated the effect of the Rho/Rho-associated protein kinase (ROCK) inhibitor fasudil on cardiac mitochondria from rats in which diabetes was induced by a combination of streptozotocin (STZ) and a sustained high-fat diet. Eight weeks after diabetes was induced by a single intraperitoneal injection of 50 mg/kg STZ followed by a sustained high-fat diet, either fasudil (5 mg/kg bid) or equivalent volumes of saline (control) were administered over four weeks. Fasudil significantly protected against the histopathologic changes of cardiac mitochondria in diabetic rats. Fasudil significantly reduced the abundances of the Rho A, ROCK 1, and ROCK 2 proteins, restored the activities of succinate dehydrogenase (SDH) and monoamine oxidase (MAO) in cardiac mitochondria, inhibited the opening of the mitochondrial permeability transition pore, and decreased the total antioxidant capacity, as well as levels of malonyldialdehyde, hydroxy radical, reduced glutathione, and superoxide dismutase in heart. Fasudil improved the structures of cardiac mitochondria and increased both SDH and MAO activities in cardiac mitochondria. These beneficial effects may be associated with the attenuation of oxidative stress caused by fasudil treatment.

Cerebral vasospasm pharmacological treatment: an update

Aneurysmal subarachnoid hemorrhage- (aSAH-) associated vasospasm constitutes a clinicopathological entity, in which reversible vasculopathy, impaired autoregulatory function, and hypovolemia take place, and lead to the reduction of cerebral perfusion and finally ischemia. Cerebral vasospasm begins most often on the third day after the ictal event and reaches the maximum on the 5th-7th postictal days. Several therapeutic modalities have been employed for preventing or reversing cerebral vasospasm. Triple "H" therapy, balloon and chemical angioplasty with superselective intra-arterial injection of vasodilators, administration of substances like magnesium sulfate, statins, fasudil hydrochloride, erythropoietin, endothelin-1 antagonists, nitric oxide progenitors, and sildenafil, are some of the therapeutic protocols, which are currently employed for managing patients with aSAH. Intense pathophysiological mechanism research has led to the identification of various mediators of cerebral vasospasm, such as endothelium-derived, vascular smooth muscle-derived, proinflammatory mediators, cytokines and adhesion molecules, stress-induced gene activation, and platelet-derived growth factors. Oral, intravenous, or intra-arterial administration of antagonists of these mediators has been suggested for treating patients suffering a-SAH vasospam. In our current study, we attempt to summate all the available pharmacological treatment modalities for managing vasospasm.

Intracranial drug delivery for subarachnoid hemorrhage

Tice and colleagues pioneered site-specific, sustained-release drug delivery to the brain almost 30 years ago. Currently there is one drug approved for use in this manner. Clinical trials in subarachnoid hemorrhage have led to approval of nimodipine for oral and intravenous use, but other drugs, such as clazosentan, hydroxymethylglutaryl CoA reductase inhibitors (statins) and magnesium, have not shown consistent clinical efficacy. We propose that intracranial delivery of drugs such as nimodipine, formulated in sustained-release preparations, are good candidates for improving outcome after subarachnoid hemorrhage because they can be administered to patients that are already undergoing surgery and who have a self-limited condition from which full recovery is possible.

A proposed definition of symptomatic vasospasm based on treatment of cerebral vasospasm after subarachnoid hemorrhage in Japan: Consensus 2009, a project of the 25 Spasm Symposium

Background:

There is a lack of unified information on diagnosis and treatment of cerebral vasospasm (CV) after subarachnoid hemorrhage (SAH) among the hospitals in Japan. Thus, the aim of the study was to define the current practice in this area based on a survey by Japanese neurosurgeons.

Methods:

A survey on diagnosis and treatment of CV was sent to 414 hospitals each of which performs >100 neurosurgeries annually.

Results:

Responses were received from 240 hospitals (58.0%). Because accurate criteria for diagnosis of symptomatic vasospasm (SVS) were used in only 33.8% of the hospitals, we proposed a clinical definition of SVS that was approved at the 25^th Spasm Symposium (Consensus 2009). This definition is simplified as follows: (1) the presence of neurological worsening; (2) no other identifiable cause of neurological worsening; and (3) confirmation of vasospasm by medical examinations. The results also showed that the Fisher CT scale is used differently for patients with ICH or IVH, with 41.3% of cases with ICH/IVH based on SAH that met Fisher criteria classified into Fisher group 1, 2 or 3, and 46.3% classified into Fisher group 4. There were no major differences in prophylactic therapies of CV and therapy for cerebral ischemia among the hospitals. Endovascular treatment for vasospasm was performed in most hospitals (78.7%); however, the criteria differed among the hospitals: (1) angiographic vasospasm and SVS appeared (37.9%), (2) only when aggressive therapy was ineffective (41.4%).

Conclusion:

We established a clinical definition of SVS based on the results of this survey (Consensus 2009).