Neuroprotective Effects of the Spin Trap Agent Disodium-[(tert-butylimino)methyl]benzene-1,3-disulfonate N -Oxide (Generic NXY-059) in a Rabbit Small Clot Embolic Stroke Model

Abstract

Background and Purpose-It has been proposed that the novel spin trap agent disodium-[(tert-butylimino)methyl]benzene-1,3-disulfonate N-oxide (NXY-059) may be useful in the treatment of ischemic stroke. However, there is little information concerning the neuroprotective properties of NXY-059 when administered after an embolic stroke. Moreover, there is no information available concerning the combination of NXY-059 with the only Food and Drug Administration-approved pharmacological agent for the treatment of acute stroke, the thrombolytic tissue plasminogen activator (tPA). Thus, we determined the effects of NXY-059G, a generic form of NXY-059, on behavioral outcome after an embolic stroke when administered alone or in combination with tPA. Methods-Male New Zealand White rabbits were embolized by injecting a suspension of small blood clots into cerebral circulation via a carotid catheter. NXY-059G (100 mg/kg) was infused intravenously 5 minutes or 3 hours after embolization, whereas control rabbits received infusions of the saline vehicle. In tPA studies, the thrombolytic was administered intravenously starting 60 minutes or 3 hours after embolization (3.3 mg/kg). In combination studies, NXY-059G was given 5 minutes after embolization, followed by the administration of tPA beginning either 60 minutes or 3 hours after embolization. Behavioral analysis was conducted 24 hours after embolization. Results-In the vehicle control group, the ES 50 value (calculated as the amount of microclots [milligrams] that produce neurological dysfunction [impairment] in 50% of the rabbits within a specific treatment group) measured 24 hours after embolism was 1.04Ϯ0.31 mg, and this was increased by 153% to 2.54Ϯ0.72 mg if NXY-059G was administered beginning 5 minutes after embolization. However, if NXY-059G was administered beginning 3 hours after embolization, the ES 50 was 2.01Ϯ0.40 mg. The rabbits treated with tPA alone had an ES 50 of 2.64Ϯ0.66 or 0.63Ϯ0.35 mg if tPA administration started 60 minutes or 3 hours after embolization, respectively. If tPA was administered after NXY-059G (started at 5 minutes), the ES 50 values were 3.15Ϯ0.50 or 2.66Ϯ0.82 if tPA administration started 60 minutes or 3 hours after embolization, respectively. Conclusions-This study suggests that NXY-059G is neuroprotective and can increase behavioral ratings if administered early after an embolic stroke. In addition, the study shows that NXY-059G can be used in combination with tPA without negative side effects. The drug combination can improve behavioral function and increase ES 50 values. However, during the short time course of the behavioral analysis, the combination was not statistically better than either drug alone.

Neuroprotection for ischemic stroke: Past, present and future

“…When treatment was begun at 4 hours after stroke onset, behavioral improvement and a 28% reduction in the overall infarct still resulted (Marshall et al, 2003). Beneficial effects of NXY-059 were also reported in a small-clot embolus model in rabbits (Lapchak et al, 2002b). In similar studies employing large-clot embolism, NXY-059 used alone increased the brain-hemorrhage rate but, when used together with tPA, appeared to reduce tPA-induced hemorrhage (Lapchak et al, 2002a).…”

A novel approach to screening for new neuroprotective compounds for the treatment of stroke

“…Using the rabbit SCEM as described previously (Lapchak et al, 2002;Lapchak et al, 2004a;Lapchak et al, 2004b;Lapchak et al, 2004c) male New Zealand white rabbits weighing 2.2-2.6 kg were anesthetized and a catheter was inserted into the common carotid artery through which microclots were injected. Briefly, the bifurcation of one carotid artery is exposed and the external carotid is ligated just distal to the bifurcation.…”

“…The large blood clots are then suspended in PBS with 0.1% bovine serum albumin and Polytron-generated fragments are sequentially passed through metal screens and nylon filters (Lapchak et al, 2002;Lapchak et al, 2004a;Lapchak et al, 2004b;Lapchak et al, 2004c). The resulting small clot suspension is then labeled with 57 Co containing NEN-Trac microspheres.…”

“…To evaluate the quantitative relationship between clot dose and behavioral deficits, logistic Sshaped quantal analysis curves are fitted to the dose-response data as originally described by Waud (Waud, 1972) and thereafter (Lapchak et al, 2002;Lapchak et al, 2004a;Lapchak et al, 2004b;Lapchak et al, 2004c;Zivin and Waud, 1992). A wide range of clot doses is used resulting in behaviorally normal and abnormal animals.…”

“…With this simple rating system, the composite result for a group of animals is quite reproducible. A separate curve is generated for each treatment condition and a statistically significant increase in the P 50 value or the amount of microclots that produce neurologic dysfunction in 50% of a group of animals (Lapchak et al, 2002;Lapchak et al, 2004a;Lapchak et al, 2004b;Lapchak et al, 2004c;Zivin and Waud, 1992) compared to control is indicative of a behavioral improvement.…”