GB2341318A

GB2341318A - A Dihydroisoquinoline (LOE 908) and Traumatic Brain Injury.

Info

Publication number: GB2341318A
Application number: GB9903524A
Authority: GB
Inventors: Helmut Ensinger; Walter Loesel; Dietrich Arndts; Andreas Leusch; Tracy Kahl Mcintosh; Kathryn Eileen Saatman; Ramesh Raghupathi
Original assignee: Boehringer Ingelheim Pharma GmbH and Co KG; University of Pennsylvania Penn
Current assignee: Boehringer Ingelheim Pharma GmbH and Co KG; University of Pennsylvania Penn
Priority date: 1998-09-14
Filing date: 1999-02-16
Publication date: 2000-03-15
Also published as: WO2000015227A1; GB9903524D0

Abstract

Fluid percussion model studies on rats indicate that LOE 908, 3,4-dihydro-6,7-dimethoxy-. a. -phenyl-N,N-bis[(2,3,4-trimethoxyphenyl)ethyl]-1-isoquinolineacetamide or a pharmaceutically acceptable salt thereof is effective for reducing motor dysfunction resulting from traumatic brain injury.

Description

2341318 Use of 3,4-cliliydi.o-6,7-diiiietlioxy-alplia-plienyl-N,N-bis[2,3,

4triiiietlioxyl)liciiyl)etllyll-l-isoquinoliiieacetaiiiide for the reduction of motor dysfunction File present invention relates to a new use of 3,4-diliydro-6,7diinctiloxy-alpliapliciiyl-N,N-bis[2,3,4-ti.iiiledioxyl)lieiiyl)ediyll-I isoquiiiolhicacetamide(LOE 908) or its pharniaceutically acceptable salts for the reduction of motor dysfunction in a patient who has experienced traumatic brain injury.

LOE 908 is a broad spectrum chanriel blocker. LOE 908 and its preparation is kilown fl-oxii WO 92/11 010. Therein tl ' ie compound is described as a cerebroprotective agent being suitable for the treatment of epilepsy and Alzlieinier's disease and particularly for treating patients who have suffered a stroke or are at risk of suffering a stroke, as well as being suitable for treating chronic infianuliatory processes and for irihibiting blood clotting. It is also shown therein that the effect of the compound is riot based oil all improvement in the blood flow through the tissues.

Stroke describes the neuronal cell damage which happens to tile surrounding brain tissue (so-called penumbra) of a thrombotic brain artery occlusion.

Trauniatic brain injury includes lesions/daniage to the neuronal tissue after incelianical inipact suchas froin bike, or inotor bike accident, a strong shock or concussion to the licad of -a person at ally age froni childhood to senescence occurring e.g. during car accidents, sudden drops etc.

Sonic of the toxic scquclac jifter stroke and traumatic brain injury inight be in comnion such as the activation of the excitotoxic glutainatergic pathway, but there are additional lesions occurring especially after a (iiiecli,-uiical) traumatic brain injury suchas vascular disruption, intraparenchyinal heinorrhage, extravasation of potentially harmful blood borne products, breakdosyn of the blood brain barrier, neuronal tissue shearing and membrane disruption.

Thus it caiuic)t be expected that a compound being active in stroke treatment will also show efficacy in the treatment of traumatic brain injury. 111 fact, it has been shown that several specific classes of compounds (such as conipetitive NMDA glutaniate antagonists), which are extraordinarily protective ill experimental models of stroke, have absolutely no-benefit whatsoever in experimental models of brain traunia.

Tlicre still is the need to provide a medicament for reducing the dysfunction caused by traumatic brain injury, especially physical brain injury in consequence of accidents.

It has now been found that, surprisingly, LOE 908 fulfils this need. This is shown by the following test results:

I. Fluid percussion model 2. Assessment of neurologic motor function damage caused by fluid percussion.

Histopathological damage Fluid percussion model.- Male rats (350-400 g) are initially anesthetized intravenously with sodium pentobarbital (Nembutal,50 mg/kg). During surgical preparation and throughout the experimental procedure, all wounds are infused with a topical anesthetic (2.0% lidocainchydrochloride). Drugs are administered through a canriula placed in the femoral vein. The femoral artery is cannulated to monitor heart rate, mean arterial blood pressure and pulse pressure, as well as to sample arterial blood gases.

With the animal in a stereotaxic frame, the scalp and temporal muscle are reflected. Next, a hollow tube (the Luer-Lok syringe through which the saline impulse is injected) is rigidly fixed with dental acrylic to the animal's skull over a 2.0 nini craniotorny centered over the left parietal cortex, midway between lambda and bregma. A piezoelectric pressure transducer affixed to the injury device will measure the pressure transient, which is recorded on a storage oscilloscope. The duration and peak pressure in atmospheres (atm) will be noted for each injury.

The fluid percussion (FP) model of head injury will be employed using the anesthetized rat. This model was initially developed by Lindgren and Rinder in the rabbit (LINDGREN, S. and RINDER, L. (1969) ACTA Physiol. Scand. 7/ 6,34035 1, "Production and distribution of intracranial and intraspinal pressure changes at sudden extradural fluid volume input in rabbits"), and utilizes hydraulicallyinduced pressure changes to produce quantifiable, mechanical deformation of the brain. The FP device for induction of brain injury was modified to accommodate a rat (McIntosh et al., (1989). The modified FP devices are manufacture at lkledical College of Virginia with modifications for the rat.

This FP device consists of a Plexiglas cylindrical reservoir bounded at one end by a Plexiglas, cork-covered plunger mounted on O-rings. The opposite end of the reservoir is fitted with a second hollow Plexiglas cylinder, which is in turn attached to a cylindrical transducer for measuring the pressure generated at the time of injury. The entire device is attached to the Luer-Lok syringe, which is rigidly fixed with dental acrylic to the opening in the aninial's skull. The dura is left intact at this opening. The Luer-Lok syringe is tightly connected to the transducer housing and the entire system is filled with 0.9% sodium chloride solution at 37C. The pendUlUln is then allowed to fall from apredetermined height, striking the plunger and forcing a rapid pulse of saline through the craniotomy and into the closed cranial cavity. The injury is recorded on a storage oscilloscope which is triggered photoelectrically by descent of the pendulum. This device produces a pulse of increased intracranial pressure of fairly constant duration 21-23 msec), and the pressure transient is associated with distortion and deformation of brain tissue. The height of the pulse is variable and can be regulated by raising or lowering the pendulum. Since the duration of the pulse is constant, the amplitude of the increased intracranial pressure (measured in atm) is used as a measure of the magnitude of the brain injury.

The above model yields a predictable degree of brain injury and simulates many aspects of head injury in humans.

In the present study, a moderate severtiy of brain injury was produced, corresponding to 2,5-2,7 atm.

Experimental Protocol Prior to injury, animals have an indwelling catheter implanted into the femoral vein. All animals are injured at a moderate severity (2.5 - 2,7 atm). At 15 min after FP brain injury, animals are randomly assigned to treatment with two doses of LOE 908 or control vehicle (equal volume). An infusion of a loading dose is performed over a 12-minute period followed by an infusion of a maintenance dose for 24 hours. After drug treatment, animals are randomly assigned to the study groups described below.

Assessment of neurologic motor function damage caused by fluid percussion:

Neurological scoring of motor function is performed at 4 ' 8 h in animals treated with LOE 908 or a control vehicle. The composite neurological scoring paradigm includes: (1) contralateral forelimb flexion upon suspension by the tail; (2) decreased resistance to lateral pulsion toward the right as compared with pulsion toward the left; (3) the ability to stand on an inclined angle-board (inclined plane) with the maximal angle at which the animal can stand vertically and/or horizontally for 2 see recorded; (4) hindlimb flexion when the forelimb remain on a hard surface and the hindlimbs are lifted up and back by the tail. All animals are graded as follows for each task: Grade 4 = normal; Grade 3 = mild deficit; Grade 2 = moderate deficit; Grade I = moderate/severe; Grade 0 = extremely severe deficit. A composite neurological score is developed. This composite scoring paradigm is extremely sensitive in depicting the correlation between neurological outcome and severity of injury.

Details of the test results:

Adul t male Sprague-Dawley rats were anesthetized (60 mg/kg pentobarbital, i.p.), and subjected to surgery and lateral fluid percussion brain injury (2.5-2.7 atm, n=38) or surgery without brain injury (n=15). At 15 min postinjury, animals received intravenous (femoral vein) LOE 908 MS at either a low dose (bolus of 2 ing/kg followed by a 24 lir infusion of 80 nig/kg; n=I 2) or a high dose (4 mg/kg bolus followed by a 24 hr infusion of 160 mg/kg; n=13D. or vehicle (n=13).

Uninjured animals received the high dose of the compound (n=8) or vehicle (n=7). Both doses of LOE 908 significantly improved motor function at 48 lus in braininjured animals compared to vehicle-treated, brain-injured animals.

Dosingparadigm Route of administration Intravenous (femoral) Vehicle 5% Xylitol in sterile water Rates 15 min following injury, 12 min infusion at 10 mUlir/kg followed by 24 hours infusion at I mi/hr/kg Dose Low: 2 mg/kg followed by 80 mg/kg High: 4 mg/kg followed by 160 mg/kg Outcome measures at 48 ho urs post-injury Composite neuroscore evaluation (includes forelinib and hindlimb flexion, lateral pulsion, and inclined plane tests; total score=28) Experimental groups n Uninjured (sham), vehicle-treated 7 Unirijitired (sham), high doSe-treated 8 Injured, vehicle-treated 1 Injured, low dose-treated 12 Injured, high dose-treated 1 Statistical analyses Vehicle-treated, injured animals were compared to veli i cletreated, sharn animals to test for significant dysfunction following brain injury. Inj ured, LOE 908 -treated groups were then compared to the vehicle- treated, injured group to test for treatment effects. Neuroscores are nonpararnetric data (presented as median scores) and are compared using Mann-Whitney U-tests.

Results 17ui-y Brain-injured animals were randomly assigned to one of three treatment groups. The vehicle, low dose LOE 908, and high dose LOE 908 groups received equivalent levels of injury (2.8 0.3, 2.7 0.3 and 2.7 0.3 atm, respectively; iiieaii s.d.) and displayed equivalent mean post-injury apnea (27,27, and 29 see, respectively) and weight loss.

Composite Neuroscore Brain injury resulted in significant motor dysfunction in vehicle-tre- ated rats (compared to vehicle-treated sham, =p<0.00 1 for composite neuroscore, p<0.05 for each individual test in the composite). Administration of high dose LOE 908 did not affect the motor function of sham animals. Compared to vehicle treatment, both the low and the high dose of LOE 908 resulted in significantly improved motor function (composite neuroscore, +=p<0.02) at 48 hours following injury. Analyses of individual tests within the composite revealed that high dose LOE 908 administration resulted in significant improvement in both left and right lateral pulsion tests (p<0.05), and low dose LOE 908 administration led to improvement in left lateral pulsion (p<0.05).

Example

Infusion solution:

stock solution: 500 mg LOE 908 mg ascorbic acid Water q.s. and 20 ml To prepare the infusioii solution, this stock solution is diluted in 500 ml 5% aqueous xylitol solution.

Composite Neuroscore + + 25.0 t 20.0.

m t U) Shwn Veh Sharn Drug in). Veh Inj. tow 1rj. ffigh.

1 injured, low dose-treated rats 2 injured, high dose-treated rats The above graph shows the assessment of neurological motor function 48 hours after brain injury or sham treatment. Animals were evaluated for motor function using four separate tests which were combined to yield a composite neuroscore with a maximum score of 28 points. Sham treated animals resolved either vehicle (Veh) or LOE 908 (Drug), while braininjured animals (Inj.) received either vehicle (Veh), low-dose LOE 908 (Low) or high-dose LOE 908 (High). Vehicletreated brain injured animals showed a significant deficit when comparted to Sham vehicle-treated animals (p<0.001). Treatment with either low or high dose LOE 908 significantly attenuated motor dysfunction when compared to vehicle treatment (+p<0.02).

Claims

1. Use of LOE 908 (as herein defined) or a pharmaceutically acceptable salt thereof for the preparation of a medicament for reducing motor dysfunction of a mammal who has experienced traumatic brain injury. 10

2. Use as claimed in claim 1, wherein said medicament is accompanied by instructions to administer a first dose of said medicament to the mammal shortly after it has received the traumatic brain injury. 15

3. Use as claimed in claim 2, wherein said instructions indicate administration of subsequent doses of said medicament over a period of at least 2 to 3 days. 20

4. Use as claimed in claim 1, wherein said medicament contains instructions to administer said medicament at a dosage sufficient to provide a plasma level of LOE 908 in the mammal of between 0.

5 yg/ml and 2 yg/ml. 25 S. Use as claimed in claim 4, wherein said plasma level is maintained for at least 1 to 2 or up to 7 days.

6. Use as claimed in any one of claims 1 to 5 substantially as hereinbefore described.