in describing preferred embodiments of the present invention , specific terminology is employed for the sake of clarity . however , the invention is not intended to be limited to the specific terminology so selected . it is to be understood that each specific element includes all technical equivalents which operate in a similar manner to accomplish a similar purpose . each reference cited here is incorporated by reference as if each were individually incorporated by reference . the term “ non - sedative barbiturate ” encompasses the family of 5 , 5 - diphenyl barbituric acid anticonvulsant compounds described in levitt et al ., u . s . pat . no . 4 , 628 , 056 , and metabolic precursors and metabolites , and derivatives and structural analogs ( including addition salts thereof ) having a non - sedative neuroprotectant activity . other barbituric acid derivatives that are non - sedating are also within the scope of the invention . derivatives , precursors , and analogs of barbituric acid include barbituric acids of the formula : wherein one or more nitrogen is substituted with lower alkyl , or a lower alkoxy substituted lower alkyl group ; or at least one of r 1 and r 2 , together with the nitrogen , forms a carbamate , an amide , or an acetal of the formamide derivative , i . e . r 1 or r 2 is co 2 r , cor or ch ( or ) 2 . methylether groups are preferred r 1 and r 2 groups and methoxymethyl is more preferred . methyl is also a preferred value for r 1 and / or r 2 . other derivatives of barbituric acids according to the invention are carbamates , amides and acetals where one or both of r 1 and r 2 is ch 2 or 5 , wherein r 5 is lower alkyl , alkylaryl or benzyl ; co 2 r 6 , wherein r 6 is lower alkyl or aryl ; cor 7 , wherein r 7 is hydrogen , lower alkyl or aryl ; or ch ( or 8 ) 2 , wherein r 8 is a lower alkyl group . preferred values for r 3 and r 4 are aryl , phenyl , phenyl substituted with a halogen or lower alkyl group , benzyl , benzyl wherein the aromatic ring is substituted with a halogen or lower alkyl group , lower alkyl or lower alkyl substituted with an aromatic moiety . aryl represents any carbocyclic ring , such as phenyl , naphthyl and higher analogues , as well as heteroaromatic rings substituted with one or more heteroatoms such as sulfur , oxygen and nitrogen . according to the invention , nonsedating barbituric acid derivatives are those where at least one of r 3 and r 4 is an aromatic ring or an aromatic ring containing moiety e . g . aryl , phenyl , substituted phenyl , benzyl , substituted benzyl or arylalkyl . preferred substituents on the aromatic rings are methyl , ethyl , and fluorine . phenyl and substituted phenyl are preferred for r 3 and r 4 . embodiments where r 3 and r 4 are both phenyl are most preferred . in preferred compounds , one of r 1 and r 2 is hydrogen , or one or both of r 1 and r 2 is methyl or alkoxymethyl , preferably methoxymethyl . at least one and preferably both of r 3 and r 4 is preferably phenyl or substituted phenyl , tolyl , fluorophenyl , ethylphenyl . as can be readily understood , salts of the above compounds are also contemplated , including organic salts , such as acid addition and base addition salts . in order to fall within the scope of this genus , the compound must ( 1 ) be a barbituric acid chemical derivative , ( 2 ) not be sedating , in the sense that the subject remains awake and alert at useful doses , that is , not anesthetized , and ( 3 ) manifest neuroprotective activity in an animal model described herein or in a human at a dose that is not toxic to the relevant animal species , or show activity in an in vitro assay now known or later discovered that is accepted as a model for in vivo neuroprotection . these barbituric acid derivatives may be both prodrugs and active ingredients in the subject , thus combining to produce the desired pharmacodynamic effect of neuroprotection . sustained levels are readily obtained with such compounds . thus , certain barbiturate compounds have been developed and have anticonvulsant activity without being sedating even at very high brain concentrations ( that would be lethal with other barbiturates ). according to the invention , such compounds are used to neuroprotect an animal at risk for or suffering from one or more ischemic episodes such as that modeled by middle cerebral artery occlusion , while these compounds do not cause the toxic effects of other barbiturates when present at concentrations required for prevention of ischemic brain damage . as described herein , non - sedative barbiturate drugs lessen or prevent ischemic brain damage in a rat model of focal cerebral ischemia produced by middle cerebral artery occlusion . this demonstrates utility in humans . in a reproducible , predictive model of cerebral ischemia known in the art , selective neuronal damage is produced in the striatum and cerebral cortex by bilateral carotid occlusion accompanied by systemic hypotension . the resulting cerebral ischemia causes a release of excitotoxic neurotransmitters and dopamine in striatum . pentobarbital inhibited this ischemia - induced release , pointing to one possible mechanism of barbiturate neuroprotection . ( 5 ) a neuroprotective dose of pentobarbital was found to be 70 mg / kg . inhibition of neurotransmitter release by several neuroprotective anesthetic agents ( isoflurane , etomidate , propofol ) was also known . the above and similar animal models ( see examples ) can be used ( 1 ) to analyze whether a non - sedative barbiturate with anticonvulsant properties but little or no anesthetic activity can provide neuroprotection in the striatum or hippocampus , and ( 2 ) to determine if the agent prevents or reduces release of neurotransmitters in response to ischemia . uncontrolled or unmodulated neurotransmitter release is one of the postulated mechanism of ischemic damage . for non - sedating barbiturates that inhibit release of neurotransmitters , this approach can serve as a biochemical assay for predicting utility of a compound according to the invention , and the invention encompasses such methods . a neuroprotective effect according to the invention can be demonstrated and characterized by performing a dose - response study and measuring statistically significant differences in neuronal damage at the various doses of the drug . dose - response curves generated in such studies can be used to compare the relative degree of neuroprotection and sedation of a test compound . cerebral ischemia is induced in rats by occlusion of the middle cerebral artery (“ mca ”) ( 7 - 9 ). the occlusion can be performed in an irreversible or reversible manner . in the latter case , after a period of obstruction , blood flow is restored . these animal preparations are thus appropriate to model various types of strokes in humans and to permit determination of a drug &# 39 ; s neuroprotective action . such models permit observation of the prevention of brain damage and the evaluation of the drugs as being useful for humans who are at risk for ischemic stroke for reduction of subsequent brain damage induced by an ischemia event . because they prevent brain damage in models of irreversible ischemia and reversible ischemia with restoration of blood flow , the compounds of the invention are also useful for treating acute ischemic stroke either alone or in combination with other agents , for example , thrombolysis such as tissue plasminogen activator that reduce the extent of brain infarction when circulation is restored . the term “ treatment ” is intended to encompass administration of compounds according to the invention prophylactically to prevent or suppress an undesired condition , and therapeutically to eliminate or reduce the extent or symptoms of the condition . treatment according to the invention is given to a human or other mammal having a disease or condition creating a need of such treatment . treatment also includes application of the compound to cells or organs in vitro . treatment may be by systemic or local administration . the non - sedative barbiturate compositions of the present invention , may be formulated into “ pharmaceutical compositions ” with appropriate pharmaceutically acceptable carriers , excipients or diluents . if appropriate , pharmaceutical compositions may be formulated into preparations including , but not limited to , solid , semi - solid , liquid , or gaseous forms , such as tablets , capsules , powders , granules , ointments , solutions , suppositories , injections , inhalants , and aerosols , in the usual ways for their respective route of administration . methods known in the art can be used to achieve time - release of the composition or to prevent metabolism , release or absorption of the composition until it has reached its intended target site . a pharmaceutically - acceptable formulation should be employed that does not inactivate the active drug of the present invention . in pharmaceutical dosage forms , the compositions may be used alone or in appropriate association , as well as in combination with , other pharmaceutically - active compounds . the pharmaceutical compositions of the present invention can be delivered via various routes and to various sites in an animal body to achieve the desired neuroprotective effect . local or systemic delivery can be accomplished by injection , infusion , application or instillation of the composition into one or more body cavities , or by inhalation or insufflation of an aerosol . parenteral administration can be by intramuscular , intravenous , intraperitoneal , subcutaneous intradermal , or topical administration . the compositions of the present invention can be provided in unit dosage form , wherein each dosage unit , e . g ., a teaspoon , tablet , solution , or suppository , contains a predetermined amount of the active drug or prodrug , alone or in appropriate combination with other pharmaceutically - active agents . the term “ unit dosage form ” refers to physically discrete units suitable as unitary dosages for human and animal subjects , each unit containing a predetermined quantity of the composition of the present invention , alone or in combination with other active agents , calculated in an amount sufficient to produce the desired effect , in association with a pharmaceutically - acceptable diluent , carrier ( e . g ., liquid carrier such as a saline solution , a buffer solution , or other physiological aqueous solution ), or vehicle , where appropriate . the specifications for the novel unit dosage forms of the present invention depend on the particular effect to be achieved and the drug &# 39 ; s particular pharmacodynamics in the particular host . an “ effective amount ” of the composition is that required to produce the desired pharmacologic effect in a host . this can be monitored using any of a number of end - points known to those skilled in the art . the “ effective dose ” will depend on the bioavailability of specific dosage forms delivered by one or another route of administration . the neuroprotective dosage and blood level of the present compounds is at least 2 - fold and preferably at least about 5 to 10 - fold the anticonvulsant dosage of a sedating barbiturate . based on rat data , the anticonvulsant ed 50 for phenobarbitol is about 50 - 100 mg / kg . a non - sedating barbiturate dose of 1 g / kg given over 7 days protects against cerebral ischemia in the rat . similar or lower doses are suitable in humans based on the enhanced absorption in humans discussed above . the amount of each active agent employed in the examples below provides general guidance for the range that can be utilized by the skilled practitioner to optimize the doses and methods of the present invention . moreover , such dose ranges do not preclude use of a higher or lower dose of a component , as might be warranted in a particular application . for example , the actual dose and schedule may vary depending on whether the compositions are administered in combination with other drugs , or depending on inter - individual differences in pharmacokinetics , drug disposition , and metabolism . similarly , amounts may vary for in vitro applications . it is within the skill in the art to readily adjust the dose in accordance with the necessities of a particular situation without undue experimentation having now generally described the invention , the same will be more readily understood through reference to the following examples which are provided by way of illustration , and are not intended to be limiting of the present invention , unless specified . the non - sedative barbiturate ( nsb ) drug is tested in rats exposed to either reversible or irreversible ischemia . varying doses of drug are administered . the neuroprotective effect is compared to a negative control ( placebo ) and a positive control , pentobarbital , a known neuroprotective but sedative barbiturate , given at doses known to reduce infarct volume in cerebral ischemia ( 1 - 4 ). animals are sacrificed several days after the onset of the ischemic insult and the brains examined to determine the volume of brain infarction as an outcome measure of the drug &# 39 ; s reduction of ischemic brain damage . the animals are examined clinically and graded prior to sacrifice to determine if the drug has conferred any beneficial effect on relevant functions following ischemic “ stroke .” four experimental models are preferred for testing the neuroprotective effects of the nsb drug . see ginsberg , m . d ., “ animal models of global and focal cerebral ischemia ,” chapter 34 in welsh , k . m . a et al ., primer on cerebrovascular diseases , academic press , new york , 1997 ; and pulsinelli w a , brierley j b . a new model of bilateral hemispheric ischemia in the unanesthetized rat , stroke 1979 may - june 10 ( 3 ): 267 - 72 . 1 . irreversible ischemia produced by middle cerebral artery ( mca ) occlusion ; 2 . reversible ischemia produced by mca occlusion ; 3 . transient global ischemia produced by cross - clamping the aorta for a defined interval ; and 4 . transient global ischemia produced by cauterizing both vertebral arteries and reversibly clamping the common carotid arteries . in each experimental model , groups of rats are treated with either : 1 . negative control ( placebo ) via nasogastric ( ng ) tube ; 2 . positive control : intraperitoneal ( ip ) dose of 70 mg / kg pentobarbital ; or 3 . the nsb compound dmmdpb ( or a compound being tested for its utility in the present invention ) via ng tube at doses between 500 mg / kg and 1500 mg / kg for 7 days prior to experimental infarctions . irreversible mca occlusion was produced by ligating the carotid artery and then inserting a filament into the origin of the mca with the animal maintained under halothane anesthesia . blood flow in the mca was measured by laser doppler and those animals in which a significant drop in blood flow occurred were considered to have experienced cerebral ischemia , and to be at risk for subsequent damage ( i . e ., a stroke ). indeed , no clinical strokes occurred in animals that did not experience a precipitous drop in mca blood flow . all the animals showing with a drop in mca blood flow experienced strokes . animals at risk were then followed behaviorally and scored by clinical findings using the bederson grading scale as either : those animals that survived for three days were sacrificed and their brains examined . animals to be sacrificed were given chloral hydrate ( 35 mg / kg ip , and their brains were fixed by intracardiac perfusion with heparinized 0 . 9 % saline followed by 10 % buffered formalin . the brains were removed from the cranial vault with care to leave the arachnoid intact with the intracranial vessels underneath . the fixed brains were frozen at 80 ° c . coronal sections 20 μm thick were cut at 400 μm intervals in a cryostat at − 20 ° c ., dried on a hot plate at 60 ° c ., fixed in 90 % ethanol for 10 minutes and stained with hematoxylin and eosin ( 7 ). infarcted brain is pale compared to the rest of the brain . the amount of infarcted brain was determined by microscopic inspection of the brain sections and calculation of infarct volumes in mm 3 . the results are shown in tables 1 and 2 below . the numbers vary between groups because not all animals experienced a drop in mca blood flow with the procedure . all animals were treated with dmmdpb dosages of 1000 mg / kg / day for 7 days . other dose ranging studies in rats treated with dmmdpb for 7 days established that female rats have substantially higher blood levels than male rats . specifically , at a dosage of dmmdpb of 500 mg / kg the total barbiturate level in males was 59 μg / ml and females 170 μg / ml . at a dosage of 1000 mg / kg the total barbiturate level in males was 77 μg / ml and females 227 μg / ml ; and at a dosage of 2000 mg / kg the total barbiturate level in males was 110 μg / ml and females 328 μg / ml . thus females consistently had blood levels 250 %- 300 % that of males at the same dosage . this data shows a type of “ dose response effect ” or “ blood level response effect ” whereby higher blood levels correlate to higher survival in female rats in the results tabulated above . thus , dmmdpb proved to protect the animals against death . other data indicated that dmmdpb treated animals did not manifest sedation compared to placebo group . in contract , the pentobarbital animals were anesthetized and immobile . the neuroprotective effects at non - sedating doses were comparable to or better than the effects of the sedative pentobarbital but without the side effects - of sedation , particularly at day two . these neuroprotective effects of dmmdpb are predictive for monomethoxymethyl diphenyl barbituric acid ( mmmdpb ) and the presumptive pharmacologically active chemical moiety diphenyl barbituric acid ( dpb ), which are metabolic products of dmmdpb . indeed , in animal studies over periods ranging from 1 - 30 days dmmdpb was rapidly metabolized to mmmdpb and eventually to dpb . results from clinical studies with humans demonstrated a pattern of blood levels similar to that seen in animals : dpb & gt ; mmmdpb & gt ; dmmdpb . again , the same pattern was shown in that blood levels of dmmdpb were minimal , while mmmdpb and dpb concentration was higher . this animal model of neuroprotection is predictive for humans because : ( a ) the metabolic behavior of this compound in animals is predictive of human metabolism , and ( b ) the anticonvulsant activity in animals correlates with anticonvulsant activity in humans . although several sedative barbituric compounds previously found to be neuroprotective in such animal models provided some benefit in human studies , their use over even relatively short time periods is precluded by their sedative and other neurological and psychological side - effects . these side effects make prophylactic treatment infeasible for patients identified as being at high risk of stroke . according to the present invention , in contrast , the nsbs have minimal side effects in humans . thus , it is now established that diphenyl barbituric acid and its precusors , analogues and derivatives constitute a class or family of compounds suitable for neuroprotection of humans . rats are pretreated as in example 1 ( above ) and a similar procedure is performed except that the filament occluding the mca is removed after 30 to 60 minutes , restoring blood flow through the mca . rats are then followed clinically for three days , graded for their degree of stroke and then sacrificed as in example . the brains are removed and examined as described above . the nsb compounds are shown to be neuroprotective under these conditions . rats are pretreated as in example 1 ( above ) and then , during ether anesthesia , the rats &# 39 ; vertebral arteries are electrocauterized through the alar foramina of the first cervical vertebra . reversible clamps are then placed loosely around the common carotid arteries . after 24 hours , working with awake rats , the carotid clasps are tightened to produce 4 - vessel occlusion . following 10 - 30 minutes of 4 - vessel occlusion , the clasps are removed and 72 hours later the animals sacrificed by perfusion fixation . untreated rats routinely demonstrate ischemic neuronal damage after 20 or 30 minutes of 4 - vessel occlusion . multiple areas of the forebrain , including the h1 and paramedian hippocampus , striatum , and posterior neocortex are evaluated . the non - sedating barbiturates are shown to be neuroprotective under these circumstances . the embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention . nothing in this specification should be considered as limiting the scope of the present invention . the above - described embodiments of the invention may be modified or varied , and elements added or omitted , without departing from the invention , as appreciated by those skilled in the art in light of the above teachings . it is therefore to be understood that , within the scope of the claims and their equivalents , the invention may be practiced otherwise than as specifically described . 1 . hoff j t , smith a l , hankinson h l , nielsen s l . barbiturate protection from cerebral infarction in primates . stroke 1975 ; 6 : 28 - 33 2 . levy d e , brierley j b . delayed pentobarbital administration limits ischemia brain damage in gerbils . 3 . lightfoote w e ii , molinari g f , chase t n . modification of cerebral ischemia damage by anesthetics . stroke 1977 ; 8 : 627 - 628 4 . corkill g , chikovani o k , mcleish i , mcdonald l w , youmans j r . timing of pentobarbital administration for brain protection in experimental stroke . surg neurol 1976 ; 147 - 149 5 . bhardwaj a , brannan t , weinberger j . pentobarbital inhibits extracellular release of dopamine in the ischemia striatum . j neural transom 1990 ; 82 : 111 - 117 6 . masuda y , utsui y , shiraishi y , karasawa t , yoshida k , shimizu m . relationships between plasma concentrations of diphenylhydantoin , phenobarbital , carbarnapezine , and 3 - sulfmoylmethyl - 1 , 2 - benzisoxazole ( ad - 810 ), a new anticonvulsant agent , and their anticonvulsant or neurotoxic effects in experimental animals . epilepsia 1979 ; 20 : 623 - 633 7 . brint s b , - jacewicz m , kiessling m , tanabe j , pulsinelli w . focal brain ischemia in the rat : methods for reproducible neocortical infarction using tandem occlusion of the distal middle cerebral and ipsilateral common carotid arteries . j cerebral blood flow metab 1988 ; 8 : 474 - 485 8 . garcia j h , wagner s , liu k - f , hu x - j . neurological deficit and extent of neuronal necrosis attributable to middle cerebral artery occlusion in rats . statistical validation . stroke 1995 ; 26 : 627 - 634 9 . garcia j h , liu k - f , ho k - l . neuronal necrosis after middle cerebral artery occlusion in wistar rats progresses at different time intervals in the caudoputamen and the cortex . stroke 1995 - 26 : 636 - 643 . 10 . stroke therapy : basic clinical and pre - clinical directions , leonard p . miller , ed . ( wiley 1999 ). 11 . ginsberg , m . d ., animal models of global and focal cerebral ischemia , chapter 34 in eds . welsh , k . m . a , caplan , l . r ., reis , p . j ., et al , primer on cerebrovascular diseases , academic press 1997 . 12 . pulsinelli w a , brierley j b . a new model of bilateral hemispheric ischemia in the unanesthetized rat , stroke 1979 may - june 10 ( 3 ): 267 - 72 13 . pulsinelli , w a , brierly j b , plum f . temporal profile of neuronal damage in a model of transient forebrain ischemia , annals of neurology , 1982 , may , 11 ( 5 ) 491 - 8 .
methods of providing neuroprotection are disclosed comprising administering a non - sedative barbiturate compound in an amount sufficient to achieve neuroprotection in a mammalian subject . preferred compounds are in the family of diphenylbarbituric acid and analogs . preferred doses for a neuroprotective effect exceed the dosage of a corresponding sedative barbiturate without sedative side - effects such as anesthesia and death .