WO2005032485A2

WO2005032485A2 - Compounds and methods for the treatment of attention-deficit hyperactivity disorder

Info

Publication number: WO2005032485A2
Application number: PCT/US2004/032632
Authority: WO
Inventors: Emer Leahy
Original assignee: Psychogenics, Inc.
Priority date: 2003-10-03
Filing date: 2004-10-01
Publication date: 2005-04-14
Also published as: WO2005032485A3

Abstract

A method for treating Attention Deficit/Hyperactivity Disorder (ADHD) using a compound of Formula (I) and related compounds is provided.

Description

COMPOUNDS AND METHODS FOR THE TREATMENT OF ATTENTION-DEFICIT HYPERACTIVITY DISORDER

FIELD OF THE INVENTION

The present invention is directed to novel compounds and methods of treating Attention-Deficit/Hyperactivity Disorder ("ADHD").

BACKGROUND OF THE INVENTION

Attention-Deficit/Hyperactivity Disorder (ADHD) is a behavior disorder characterized by problems with control of attention and activity-impulsivity. The attentional difficulties and impulsivity associated with ADHD have been persuasively documented in laboratory investigations using cognitive tasks. Although these problems typically present together, one may be present without the other to qualify for a diagnosis (American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 4^th Ed, 1994 (DSM-IV)). Generally, attention deficit or inattention becomes apparent when a child enters elementary school. A modified form of the disorder can persist into adulthood (Diagnostic and Statistical Manual of Mental Disorders, 3^rd Ed, 1987). With respect to the attention component, the child is easily distracted by outside stimuli, neglects finishing tasks, and has difficulty maintaining attention. Regarding the activity component, the child is often fidgety, impulsive, and overactive. The symptoms of ADHD may be apparent as young as preschoolers and are virtually always present prior to the age of 7 (Halperin et al. Journal of the American Academy of Child and Adolescent Psychiatry, Vol. 32: 1038-1043, 1993). According to the Diagnostic and Statistical Manual of Mental Disorders, 4^th Ed, diagnostic criteria for Attention-Deficit/Hyperactivity Disorder relate to symptoms associated with either inattention or hyperactivity-impulsivity. ADHD associated with inattention is diagnosed if six (or more) of the following symptoms of inattention have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level. Inattention is characterized by: (a) often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities, (b) often has difficulty sustaining attention in tasks or play activities, (c) often does not seem to listen when spoken to directly, (d) often does not follow through on instructions and fails to finish school work, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions), (e) often has difficulty organizing tasks and activities, (f) often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework), (g) often loses things necessary for tasks or activities (e.g, toys, school assignments, pencils, books, or tools), (h) is often easily distracted by extraneous stimuli, and (i) is often forgetful in daily activities. ADHD associated with hyperactivity-impulsivity is diagnosed if six (or more) of the following symptoms of hyperactivity-impulsivity have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level. Hyperactivity is characterized by: (a) often fidgets with hands or feet or squirms in seat, (b) often leaves seat in classroom or in other situations in which remaining seated is expected, (c) often runs about or climbs excessively in situations in which it is inappropriate (in adolescents or adults, may be limited to subjective feelings of restlessness), (d) often has difficulty playing or engaging in leisure activities quietly, (e) is often "on the go" or often acts as if "driven by a motor," and (f) often talks excessively. Implusivity is characterized by: (g) often blurts out answers before questions have been completed, (h) often has difficulty awaiting turn, and (i) often interrupts or intrudes on others (e.g. butts into conversations or games). Many of the symptoms that are characteristic of ADHD occur occasionally in normal children. Children with ADHD, however, exhibit these symptoms frequently, which tend to interfere with the child's day to day functioning. Such children are often challenged by academic underachievement resulting in poor school performance, excitability, and impaired interpersonal relationships. ADHD affects 2-6% of grade school children. Pediatricians report that approximately 4% of their patients have ADHD; however, in practice the diagnosis is made in children who meet several, but not all of the diagnostic criteria that is recommended in DSM-IV (Wolraich et al. Pediatrics, Vol. 86(1): 95-101, 1990). Boys are four times more likely to have the disorder than girls and the disorder is found in all cultures (Ross & Ross, Hyperactivity, New York, 1982). The most common treatment of ADHD is psychomotor stimulants. Safer & Krager (1988) reported that 99% of the children with ADHD were treated with stimulants, of which 93% were given methylphenidate hydrochloride (Ritalin), and the remainder were given dextroamphetamine sulfate (d-amphetamine) or pemoline (Safer & Krager, Journal of the American Medical Association, Vol. 260: 2256- 2258, 1988). Four separate psychostimulant medications consistently reduce the central features of ADHD, particularly the symptoms of hyperactivity, impulsivity, and inattention: methylphenidate, dextroamphetamine, pemoline, and a mixture of amphetamine salts (Spender et al. Archives of General Psychiatry, Vol. 52: 434- 443, 1995). These drugs block uptake sites for catecholamines on presynaptic neurons or stimulate the release of granular stores of catecholamines. They are metabolized, leave the body fairly rapidly, and have a therapeutic duration of action of over 1 to 4 hours. The psychostimulants do not appear, however, to make long- term changes in social or academic skills (Pelham et al. Journal of Clinical Child Psychology, Vol. 27: 190-205, 1998). Stimulants are generally started at a low dose and adjusted weekly. Common stimulant side effects include insomnia, decreased appetite, stomachaches, headaches, and jitteriness. Children who cannot tolerate psychostimulants often use the antidepressant bupropion. While bupropion is not as effective as stimulants, it may be used as an adjunct to augment stimulant treatment. Individuals with ADHD have been reported to have impairments in their ability to perceive intervals of time. Time perception is a useful measure of cognitive function, sensitive to dopaminergic and cholinergic manipulations in animals and humans. As in all behavioral tasks, several processes underlie good steady state performance in a temporal task. These behavioral tasks include: attention, motivation, short and long term memory, motor coordination, and instrumental learning. Scaling, discrimination, and reproduction are the three main types of temporal tasks that have been identified. In scaling subjects must, for example, categorize a stimulus into a given set of categories ("that was a long duration") or verbally estimate the duration ("that was a 4 s duration"). In discrimination a comparison is made between two durations ("the second stimulus was longer than the first"). Finally, in reproduction a response is made that bears some relation with the stimulus (e.g. only responses that are as long or longer than the stimulus are correct). Time perception is a particularly effective measure for testing cognitive deficits in ADHD individuals. For example, Conners & Levin (1996) showed that ^■ ADHD adults improve in measures of attention and timing with the administration of nicotine (Conners & Levin, Psychopharmacol. Bulletin, Vol. 32(1): 67-73, 1996). Nicotine, like the psychostimulants methylphenidate and dextroamphetamine, acts as an indirect dopamine agonist and improves attention and arousal. Studies indicate that adults and adolescents with ADHD smoke much more frequently than normal individuals or those with other psychiatric conditions, perhaps as a form of self-medication for ADHD symptoms. The results indicated that there was a significant clinician-rated global improvement, self-rated vigor and concentration, and improved performance on chronometric measures of attention and timing accuracy, and side effects were minimal (Conners & Levin, supra). Castellanos (1996) concluded that ADHD is a genetically programmed disorder of brain development resulting from altered function of the frontal -striatal- pallidal-thalamocortical loops which regulates cognitive processes, attention, and motor output behaviors (Castellanos et al, Archs gen Psychiat, Vol. 53: 607-616, 1996). Although the precise etiology of ADHD is unknown, neurotransmitter deficits, genetics, and perinatal complications have been implicated. Thus, current methods of treating ADHD provide inadequate treatment for some patients and/or have side effects that limit their usefulness. SUMMARY OF INVENTION

This invention relates to methods and compositions useful for treating ADHD. The compounds for use in the invention are believed to be effective in the treatment of ADHD and exhibit reduced side effects, as compared to other available therapeutics. Treatment of ADHD according to this invention may be used to reduce one or more of any of the diagnostic criteria associated with ADHD. One object of the invention is to provide a method for treating ADHD by administering to an individual a therapeutically effective amount of a compound of Formula 1:

Formula 1

and salts thereof, wherein RpP^ are each independently selected from the group consisting of hydrogen and Cι-C₆ substituted and unsubstituted, saturated and unsaturated alkyl groups; and further wherein the dotted lines represent either a bond or the absence of a bond, provided that the nitrogen atom is connected to the bicyclic moiety either directly at the 2-carbon, or indirectly through the propyl chain at the 1 -carbon, or both; with the proviso that Ri may be absent when the nitrogen atom is connected directly at the 2-carbon; and a pharmaceutically acceptable carrier. It is noted that P^ may be at any position on the bicyclic structure. Further, the compound may be a racemate or a single diastereomer or enantiomer or a pharmaceutically acceptable acid addition salt or prodrug thereof. According to the structure, the bond connecting the 1 -carbon and the 2-carbon may be either a single bond or a double bond, depending on whether the dotted bond is present or not. Additional embodiments of the invention are compounds according to Formula 2 below which are also useful in the methods of the invention for treating ADHD. Another object of the invention is to provide pharmaceutical compositions for the treatment of inattention and/or hyperactivity-impulsivity associated with ADHD that have reduced side effects as compared to other available treatments. By "associated with" is meant a symptom exhibited by a person who suffers from either diagnosed or undiagnosed ADHD. An individual is a candidate for treatment if the individual would benefit from the treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the invention and are not meant to limit the scope of the invention as encompassed by the claims. FIG. 1 - Graphs depict time course curves for C3H mice in the Peak Procedure (30 second reinforcement interval) after administration of 0.1, 0.03, and 0.01 mg/kg of Formula 2 with water vehicle. FIG. 2 - Graphs depict time course curves for C3H mice in the Peak Procedure (45 second reinforcement interval) after administration of 0.1, 0.03, and 0.01 mg/kg of Formula 2 with water vehicle. FIG. 3 - Graphs depict the relative response rate of C57BL/6J mice in the Peak Procedure (30 second reinforcement interval) after administration of 1, 2, or 4 mg/kg of d-amphetamine. FIG. 4 - Graph depicts the effect of 4 mg/kg d-amphetamine on locomotor activity in Coloboma mice, as measured by distance traveled in a fixed time period. FIG. 5 - Graphs depict the effect of Formula 4 on locomotor activity in Coloboma mice, as measured by distance traveled in a fixed time period. FIG. 6 - Graphs depict the effect of Formula 2 on locomotor activity in Coloboma mice, as measured by distance traveled in a fixed time period. FIG. 7 - Graphs depict the effect of atomoxetine on locomotor activity in Coloboma mice, as measured by distance traveled in a fixed time period. FIG. 8 - Graph presents a hypothetical analysis of variance. FIG. 9 - Graph presents a hypothetical time trial in order to demonstrate variance. FIG. 10- Standard Deviation of the Peak Response for Formula 2. FIG. 11- Graphs depict the effect of Formula 2 on locomotor activity in Coloboma mice, as measured by distance traveled and zones crossed in a fixed time period. FIG. 12- Graphs depict the effect of atomoxetine on locomotor activity in Coloboma mice, as measured by distance traveled and zones crossed in a fixed time period. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method of treating ADHD. Unlike traditional therapeutics, which have the potential to be abused and/or have undesirable side effects, the present invention is not anticipated to have the abuse potential of psychostimulants, the most widely prescribed current pharmacological treatment, and may have a side effect profile distinct from other types of pharmacologic therapeutics. Therefore, the method of ADHD treatment provided by this invention is anticipated to be more tolerable for certain patients. ADHD is diagnosed based on an individual possessing a constellation of th symptoms recognized in the art and as defined according to the DSM 4 Ed, supra, associated with ADHD. The compounds of the current invention may be used according to this invention to treat ADHD, and/or the specific symptoms or various combinations of symptoms associated with ADHD. Symptoms associated with inattention are believed to be particularly susceptible to treatment with the methods according to this invention. However, other components such as, for example, hyperactivity-impulsivity, may be treated by this invention. Treatment of ADHD according to this invention is provided by administering to an individual who would benefit a therapeutically effective amount of a compound of Formula 1:

Formula 1

and salts thereof, wherein R₁-R₄. are each independently selected from the group consisting of hydrogen and Cι-C₆ substituted and unsubstituted, saturated and unsaturated alkyl groups; and further wherein the dotted lines represent either a bond or the absence of a bond, provided that the nitrogen atom is connected to the bicyclic moiety either directly at the 2-carbon, or indirectly through the propyl chain at the 1 -carbon, or both; with the proviso that Ri may be absent when the nitrogen atom is connected directly at the 2-carbon; and a pharmaceutically acceptable carrier. It is further understood that R may occur multiple times at any position on the bicyclic structure; and that the compound may be a racemate or a single diastereomer or enantiomer, or a pharmaceutically acceptable acid addition salt thereof. This invention also includes the use of prodrugs of the compounds of Formula 1, specifically derivatives of the compounds of Formula 1 that are inactive but are converted to an active form in the body following administration. A -C₆ substituted or unsubstituted, saturated or unsaturated alkyl group is a group with a carbon chain of up to six carbons, with any variety of substituents, including but not limited to, hydroxyls, thiols, acetyls, amino groups, halogens, chalcogens, ethers, and the like. ADHD, and/or symptoms associated with ADHD, are treated according to this invention by administering therapeutic dosages of compounds according to Formula 1 to a person who would benefit from the treatment. A person who would benefit from the treatment includes a person with a diagnosis of ADHD, as well as someone who suffers from one or more of the symptoms of ADHD. Juveniles diagnosed with ADHD or who suffer from the symptoms of ADHD are a particular category of persons who would benefit from the use of the invention. A preferred compound according to the invention is a compound of Formula 2:

and pharmaceutically acceptable salts thereof. A particularly preferred compound according to the invention is the enantiomer of2H-[l]Benzopyrano[3,4-b]pyridine, l,3,4,4a,5,10b-hexahydro-10- methoxy-4-propyl, shown as Formula 3:

Formula 3

and salts thereof. The compound is described in US Pat. 4,604,397, the contents of which are incorporated by reference in their entirety. The hydrochloride salt of the above compound is assigned CAS Registry Number 100746-36-9. Another non-limiting representative of the class of compounds within the scope of the current invention is 2H-l-Benzopyran-3 -amine, 3,4-dihydro-5- methoxy-N,N-dipropyl , shown as Formula 4:

and salts, racemates, and enantiomers thereof. The compound is described in US Pat. 4,992,465, the contents of which are incorporated by reference in their entirety. One enantiomer of the above compound is assigned CAS Registry Number 118286- 92-3. The compound of Formula 4 is also known as 5-Methoxy-3- dipropylaminochroman. Psychoactive substances such as d-amphetamines typically show a U-shape curve, with low doses being cognitive enhancers, and high doses being disruptive of cognitive performance. The mechanism underlying these U-shape curves is poorly understood, with one possibility being the differential action on pre- and postsynaptic dopamine D2 receptors. It is possible that low doses preferentially affect the post- (or pre-) synaptic receptors, and that only higher doses affect both types. The differential action could be the result of different binding characteristics

(due to subtle changes in the receptors), or to differences in the amount of receptor reserve (where high receptor reserve results in a stronger effect). This dual pre- and postsynaptic action of dopamine (and of dopamine agonists) is mimicked in the serotonergic system, where the serotonin 1A and IB receptors exist as both autoreceptors (presynaptic) and heteroreceptors (postsynaptic) and have opposite effects. Presynaptic action typically results in a reduction of neurotransmitter release (and less activation of target receptors), whereas postsynaptic action results in more activation of target receptors. Although the main target of d-amphetamine- like drugs (and of bupropion, one antidepressant used for ADHD when adverse reactions prevent the use of d-amphetamines) is the dopaminergic system, strong interactions between dopamine and serotonin are well known. As a result, drugs that affect the serotonin system will very likely have secondary effects in the dopaminergic system. Moreover, serotonergic drugs that have a dual pre- and postsynaptic action would be expected to show U-shaped responses. Thus, a drug which acts as a cognitive enhancer at low doses, and disrupts performance at high doses, may be a drug that mimics d-amphetamine-like effects, and therefore may be of value in the treatment of ADHD. At present, seventeen different serotonin receptors are known. Three main 5- HT receptor subclasses have been identified as 5-HT1, 5-HT2, and 5-HT3. Additionally, four minor 5-HT receptor subclasses have been identified as 5-HT4 through 5-HT7. Radioligand binding studies have revealed at least four subtypes of the 5-HT1 binding site (5-HT1A, IB, 1C and ID). While many compounds that interact with serotonin receptors are known as anxiolytics and serotonergics, specific classes of these compounds have not previously been shown to be effective in the treatment of ADHD. While not wishing to be bound by theory, it is believed that the compounds of Formula 1 are 5-HT1 A agonists/5 -HT2 antagonists that can be used effectively as a treatment for ADHD, while not suffering from the drawbacks of current treatments. The dose of the compound used in treating ADHD in accordance with the invention will vary in the usual way with the seriousness of the disorder, the weight, and metabolic health of the sufferer. The preferred initial dose for the general patient population will be determined by routine dose-ranging studies, as are conducted, for example, during clinical trials. Therapeutically effective doses for individual patients may be determined, by titrating the amount of drug given to the individual to arrive at the desired therapeutic or prophylactic effect, while minimizing side effects. A preferred initial dose for this compound, may be estimated to be between about 0.01 mg/kg/day and 100 mg/kg/day. More preferably, the initial dose is estimated to be between 0.3 mg/kg/day and 30 mg/kg/day. Even more preferred, the initial dose is estimated to be between 0.5 mg/kg/day and 5 mg/kg/day. The most preferred initial dose is estimated to be between 0.75 mg/kg/day and 3 mg/kg/day. Administration of the compounds of this invention may be by any method used for administering therapeutics, such as for example oral, parenteral, intravenous, intramuscular, subcutaneous, or rectal administration. In addition to comprising a compound of Formula 1 or a salt or pro-drug thereof, the pharmaceutical compositions for use with this invention may also comprise a pharmaceutically acceptable carrier. Such carriers may comprise additives, such as preservatives, excipients, fillers, wetting agents, binders, disintegrants, buffers may also be present in the compositions of the invention. Suitable additives may be, for example magnesium and calcium carbonates, carboxymethylcellulose, starches, sugars, gums, magnesium or calcium stearate, coloring or flavoring agents, and the like. There exists a wide variety of pharmaceutically acceptable additives for pharmaceutical dosage forms, and selection of appropriate additives is a routine matter for those skilled in art of pharmaceutical formulation. The compositions may be in the form of tablets, capsules, powders, granules, lozenges, suppositories, reconstitutable powders, or liquid preparations such as oral or sterile parenteral solutions or suspensions as well as transdermal formulations. The solutions may be aqueous or non-aqueous. Suitable salts with respect to pharmaceutical acceptability can include hydrochlorides, hydrobromides, sulphates, methanesulphonates, nitrates, maleates, acetates, citrates, fumarates, tartrates, succinates, benzoates and amino acid salts. In order to obtain consistency of administration it is preferred that a composition of the invention is in the form of a unit dose. Unit dose forms for oral administration may be tablets, capsules, and the like, and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; and carriers or fillers, for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine. Additives may include disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycolate or microcrystalline cellulose; preservatives, and pharmaceutically acceptable wetting agents such as sodium lauryl sulphate. In addition to unit dose forms, multi-dosage forms are also contemplated to be within the scope of the invention. Delayed-release compositions, for example those prepared by employing slow-release coatings, micro-encapsulation, and/or slowly-dissolving polymer carriers, will also be apparent to those skilled in the art, and are contemplated to be within the scope of the invention. The solid oral compositions may be prepared by conventional methods of blending, filling, tabletting or the like. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers. Such operations are conventional in the art. The tablets may be coated according to methods well known in normal pharmaceutical practice, for example with an enteric coating. Oral liquid preparations may be in the form of, for example, emulsions, syrups, or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example sorbitol syrup, methyl cellulose, gelatin, hydroxyethylcellulose, carboxymethylcellulose, aluminum stearate gel, and hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (which may include edible oils), for example almond oil or fractionated coconut oil, oily esters such as esters of glycerin, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid; and if desired conventional flavoring or coloring agents. For parenteral administration, fluid unit dosage forms are prepared utilizing the compound and a sterile vehicle, and, depending on the concentration used, can be either suspended or dissolved in the vehicle. In preparing solutions the compound can be dissolved in water or saline for injection and filter sterilized before filling into a suitable vial or ampoule and sealing. Advantageously, additives such as a local anaesthetic, preservative and buffering agent can be dissolved in the vehicle. Suitable buffering agents are, for example, phosphate and citrate salts. To enhance the stability, the composition can be frozen after filling into the vial and the water removed under vacuum. Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilization cannot be accomplished by filtration. The compound can be sterilized by conventional means, for example by exposure to radiation or ethylene oxide, before being suspended in the sterile vehicle. Advantageously, a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound. The invention will be explained in more detail below by way of examples. COMPOUND OF FORMULA 2 The synthesis of the compound of Formula 2 started with commercially available 3-methoxyphenol. Alkylation of 3-methoxyphenol with propargyl bromide in the presence of potassium carbonate at reflux for 16 hours yielded the propargyl ether of 3-methoxyphenol. The propargyl ether was reacted with n-BuLi and 1- bromo-3-chloropropane initially at -40°C with warming to room temperature overnight to yield the monoalkylated product. The resulting chloride was directly reacted with potassium phthalimide at 60°C for 20 hours. The phthalimido compound was cyclized under thermolysis conditions (diethylaniline, 195-200°C, 30 hours) to yield a mixture of the 8- and 10-methoxy regioisomers in a 1:1 ratio. The phthalimido protecting group was removed with hydrazine in water at reflux for 2 hours to yield the compound of Formula 2, obtained as the hydrochloride salt.

COMPARATIVE EXAMPLES Comparative Examples are provided for the known ADHD treatments d- amphetamine and atomoxetine. While the Comparative Examples are believed to work by different mechanisms of action, they provide positive references to substantiate the validity of the model system.

EXAMPLE 1: Peak Procedure The peak procedure is a behavioral model designed to assess an animal's ability to learn an appropriate time period in which to perform a task and a time period in which the animal will be rewarded if the task is performed. The model provides information concerning excitatory and inhibitory components of behavior, as subjects must respond to perform a task when appropriate and stop responding in an "empty trial" when time for reward has elapsed and the reward has not been delivered. The task is sensitive to conditions where there is a failure in inhibitory mechanisms, such as seems to be the case for ADHD (Pliszka et al, Biol. Psychiatry, 48:238-46, 2000). For additional information, see also Abner et al, International Journal of Comparative Psychology, 14:189-210, 2001. In the peak procedure, mice are trained to work for food that is delivered at the same time in each trial, but withdrawn in some unreinforced trials. Typically, the response rate increases up to a maximum around the reinforcement time, and then decreases to a low toward the end of the trial. The shape of the response rate indicates whether the animal is sensitive to the time of reinforcement. To be able to perform well in this model, the animals need to be able to learn several tasks. First, the animal must make an association between a response (lever pressing, nose poking or key pecking) and the delivery of reward. Second, the animal must be able to perceive and remember time. Third, the animal must act on its remembered time by starting and then stopping or inhibiting the response. Fourth, the animal must be able to compare the elapsed time in the trials with its remembered time to reinforcement. In each trial the time clock is reset, and the animal must reset its internal "counter," i.e., at the beginning of each trial animals should start "timing" the trial time from zero. The ability to perform this task depends on the animal's working memory. Starting the internal clock at the beginning of the trial requires that the animal pays attention to the trial start time, which could be in the form of a visual signal, or as reported herein, the introduction of a lever into the experimental chamber. Failure to attend resulted in higher variability and a loss of accuracy during trial performance. Accuracy is measured by looking at the shape of the response function; therefore, if the response function is sharper and centered on the reinforcement time it supports a conclusion that attentional processes have been heightened. Mice were food deprived to 85-90%) of their free-feeding body weight by supplementing food earned during experimental sessions with a measured amount after the session had ended. For the d-amphetamine dose response curve, C57BL/6J mice were used (n=14). For the study on the compound of Formula 2, C3H mice were used (n=12). Once deprived, animals were trained to lever-press in an operant box (Med Associates) using ultrasensive levers. During the training, food was delivered after any one press of the lever. Once lever-pressing was robust (about 1 week), a fixed interval of 10 seconds was introduced between the beginning of a trial (when the lever is introduced into the chamber) and the reinforced response. All premature responses had no programmed consequences. After one week the fixed interval was increased to 30 seconds and animals were trained on this new fixed interval until response curves were stable. The last phase of training included empty or "peak" trials in which reinforcement was withdrawn and the trial continued for 3 times the fixed interval. Once the performance during peak trials was stable, a dose response study was initiated. Drug injections were delivered 30 minutes prior to the session. Doses were scheduled on Monday, Wednesday and Friday, with Tuesday and Thursday being normal sessions without a drug. Formula 2 dose responses were done on the same mice with at least 1 week of washout period. During this time all responses were unreinforced. Responses during these peak trials were recorded and transformed into a relative responding measure by dividing the number of responses in each 5 minute bin by the maximum response rate at any time interval in that trial. After relative responses had been calculated for each trial, an Analysis of Variance (ANOVA) with trial time and dose as within factors was performed. Significant interactions were followed up by planned pair-wise comparisons between the vehicle response and the corresponding drug dose response. In subjects with problems of inhibition and response control, it will be beneficial to find a drug that improves performance by sharpening the response curve and providing the subject with greater control over the start and stop time for response. The experiments with mice and the timing procedure were designed to maximize the chance of finding drugs that improve performance. D-amphetamine was tested in low to moderately high doses as a positive reference. Figure 3 shows the response pattern obtained with d-amphetamine. At the lower doses, 1 and 2 mg/kg, the d-amphetamine curve demonstrates a higher peak in the curve followed by a rapid decrease, relative to saline (Figures 3A, 3B). Conversely, at the higher 4 mg/kg dose, the d-amphetamine curve does not peak as high as the lower dose and the curve is flatter (Figure 3C). Times at which pairwise comparisons between saline and d-amphetamine reached significance are indicated on the graphs. ANOVA revealed a significant dose x trial time interaction, p < 0.001. For analysis of the affect of the compound of Formula 2, the peak procedure was followed as described above, but a second phase was added during which mice were trained to time two different intervals at the same time. Each animal went through two blocks of testing, with either a 30 second or a 45 second fixed interval, in randomized order. The compound of Formula 2 sharpened the response curve during peak trials, especially for the shorter interval and at the lowest dose. Figures 1 and 2 show the relative response for the peak interval 30 s and 45 s, respectively, where asterisks indicate significant planned comparisons between the dose group and control (p <.05) and trends (p<.15). Start-Stop Analysis: To find the source of the sharpening of the curve, we performed a more detailed analysis of the response curve. The first analysis removed performance effects by focusing on relative responding. This transformation focuses the analysis on the temporal location of the maximum responding and on the sharpness of the response curve. Looking at average individual relative response curves, however, may obscure other effects as Figure 8 illustrates with hypothetical data. In Figure 8a, bursts of responding that are more or less centered at the same time, start and end at different times every trial. In Figure 8b bursts of similar spread happen at different times during the trials. Both hypothetical response patterns may show the same average relative responding, the same average peak time, start, stop and spread of responding. The factor that differentiates both patterns is the variability between trials of certain measures. For both responding patterns the variability of the start and stop is similar but the variability of the spread is large in Figure 8a, and small in Figure 8b. Conversely, the variability of the peak time is small in Figure 8a, but large in Figure

8b. Figure 9 shows an example of a peak trial analyzed with the start-stop fitting procedure. The horizontal lines superimposed on the response rate show the best fit of the start-stop analysis routine with the resulting best five segments describing both the main burst of responding around reinforcement time and a second response burst towards the end of the trial. It is assumed that a compound with therapeutic potential would improve both the accuracy and the acuity of the temporal response. Accuracy will be measured mainly by the average position of the peak, and acuity will be measured by both the average spread of the distribution and by the trial -by-trial variability of responding. Thus a good compound may shift the peak time from a time later than the reinforcement time to the exact reinforcement time, reduce the spread of the response burst, and reduce the variability of both the peak and the spread. Conversely, any drug that produces the opposite effects will be deleterious. The results of the Start-Stop analysis for the compound of Formula 2 are presented in Figure 10. We compared the start, stop, peak and spread of response burst of each dose group against the vehicle control using a Wilcoxson test. The mean of each of these measures, which describes the position of the response burst, its start and its stop, did not show a significant effect by the compound. The variability of the response burst, however, showed a tendency to decrease with the lower doses of the compound. Figure 10 shows the variability of the peak of the response burst (its middle) as measured by the standard deviation (SD) somewhat decreased with the low dose (p<.l 1, marked with a ~) and clearly decreased with the middle dose (p < .007, marked with two asterisks) of the compound. As discussed above, since high variability in response is a hallmark for attention deficit, a drug that reduces variability has clear therapeutic potential. In conclusion, the compound of Formula 2 improved performance in the Peak Procedure test and is expected to be useful in the treatment of ADHD and associated symptoms thereof.

EXAMPLE 2: Open Field Activity of Coloboma Mice The Coloboma (Cm) mutant mouse has been proposed as a rodent model for ADHD (for review, see Wilson, Neurosci. Biobehav. Rev, 24:51-57, 2000). The rationale for this proposal is three fold: first, Cm mutants (heterozygote) exhibit elevated spontaneous locomotor hyperactivity which averages three to four times the activity of wild-type littermates (Hess et al, J. Neurosci, 12:2865-2874, 1992; Hess et al, J. Neurosci, 16:3104-3111, 1996); second, this Cm mutation-associated hyperactivity can be ameliorated by low and moderate doses (2 - 16 mg/kg) of D- amphetamine (Hess et al, 1996, supra), a psychostimulant commonly prescribed to treat ADHD; and lastly, Cm mutant mice exhibit delays in achieving complex neurodevelopmental milestones in behavior (Heyser et al. Brain Res. Dev. Brain Res, 89:264-269, 1995) and deficits in hippocampal physiology and learning performance (Steffensen et al. Synapse, 22:281-289, 1996; Raber et al, J. Neurochem, 68:176-186, 1997) which may correspond to impairments seen in ADHD. The genetic defects associated with Cm mutant mice include a deletion of the gene Snap (Hess et al, 1992, supra; Hess et al, Genomics, 21:257-261, 1994).

Snap encodes SNAP-25, which is a key component of the synaptic vesicle docking and fusion complex required for regulated synaptic transmission. As a result, Cm mutant animals show marked deficits in Ca -dependent dopamine release (Raber et al, supra). This hypofunctioning DA system, which may involve meso-cortical, meso-limbic, as well as nigro-striatal circuitries has been suggested as a possible mechanism underlying hyperactivity associated with Cm mutation (Sagvolden, et al, Behav. Brain Res, 94:61-71, 1998; Sagvolden and Sergeant, Behav. Brain Res, 94:1-10, 1998). D-amphetamine, but not methylphenidate, normalizes the hyperactivity in Cm mutant mice; in both control and Cm mutants, methylphenidate increases locomotor activity in a dose-dependent manner (Hess et al, 1996, supra). The differential effect of these two ADHD medicaments, which both act at the presynaptic terminal, has been attributed to the differing mechanisms of action of increasing synaptic DA concentrations (Hess et al, 1996, supra). It has now been surprisingly found that compounds of Formulas 2 and 4 produce a d-amphetamine-like effect on hyperactivity in Coloboma mice. The effect is thought to be due to 5-HT1A agonism/5-HT2 antagonism. Animals Heterozygote Coloboma mice were originally purchased from The Jackson Laboratory (Bar Harbor, ME) and were bred and maintained in our colony. For the tests with d-amphetamine (see Figure 4), 20 Cm mice were tested and 25 WT mice were tested. The breakdown of groupings was 11 mice in the Cm + d-amphetamine group, 9 mice in the Cm + vehicle group, 12 mice in the WT + vehicle, and 13 mice in the WT + d-amphetamine group. In Figure 5, mice were tested with Formula 4 compound (n=10-l 1). In Figures 6 and 7, Formula 2 and atomoxetine were tested, respectively (n=12 for each grouping, total of 48 Cm and 48 WT for each figure). Behavioral Testing Open-field testing was performed under normal lighting conditions. Mice were brought into the experimental room and allowed at least 1 hr of acclimatization. Thirty minutes prior to testing, animals received an i.p. injection of either a test compound or vehicle. The mice were then placed in the activity monitor arenas (27 x 27 x 20 cm, Med Associates). Four animals of matching genotype and treatment were tested at one time. Each testing session lasted 40 minutes, after which animals were returned to their home cages. An automated infrared beam array system measured locomotor activity (total distance traveled) and number of center entries (zone crossings). Results The data reveal a significant genotypic effect on parameters of hyperactivity that is reduced by treatment with Formulas 2 and 4. Coloboma mutant mice are hyperactive relative to wild-type mice, as measured by increased locomotor activity. The genotype-related difference in locomotion was, however, largely and significantly diminished in treated animals with Formula 2 at the lowest dose tested (0.1 mg/kg), as shown in Figures 6 and 11, and with Formula 4 at 1 mg/kg, as shown in Figure 5, respectively. Administration of atomoxetine significantly diminished the genotype-related difference in locomotion between at the lower doses (0.1 mg/kg and 0.3 mg/kg), as shown in Figures 7 and 12. At the higher dose of 0.9 mg/kg, however, atomoxetine failed to normalize the locomotion of the Cm mutant mice. Administration of d-amphetamine, 4 mg/kg, to wild-type mice had a stimulatory effect, significantly increasing total distance traveled, as illustrated in Figure 4 (3116 + 338 vs. 11657 + 2370 cm; ANOVA F(l,15) = 11.276, p = 0.0043). By contrast, the same dose of d-amphetamine administered to Cm mutant mice significantly decreased total distance traveled relative to saline-treated Cm mutants (18386 ± 6387 vs. 5966 + 1938 cm; ANOVA F(l,l 1) = 5.355, p = 0.0459) to within the range of saline-treated wild-type mice. D-amphetamine effectively normalized the hyperactive locomotor behavior of the Coloboma mutant mice, significantly decreasing locomotion in the Cm mutant mice. ANOVA revealed a significant treatment x genotype interaction (F(l,25) = 11.038, p = 0.0027). It has previously been shown that the psychostimulant anti-ADHD agents d- amphetamine, but not methylphenidate, reinstated normal locomotor activity of the Cm mutants, suggesting an inconsistent effect of psychostimulants on this model of hyperactivity (Hess et. al, 1996, supra). In summary, the compounds of Formula 2 and 4 are acting like the anti-ADHD agent d-amphetamine in the Cm animal model of ADHD, but lack the adverse stimulant properties of d-amphetamine observed in wild-type mice, demonstrating the therapeutic potential and advantages in the treatment of ADHD. The above Examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Claims

We claim:

1. A compound according to Formula 2:

and salts thereof.

2. The compound according to claim 1, wherein the salts are selected from the group consisting of hydrochlorides, hydrobromides, sulphates, methanesulphonates, nitrates, maleates, acetates, citrates, fumarates, tartrates, succinates, benzoates and amino acid salts.

3. A composition comprising the compound according to claim 1 and a pharmaceutically acceptable carrier.

4. The composition according to claim 3, wherein the pharmaceutically acceptable carrier is selected from the group consisting of suspensions, tablets, capsules, powders, granules, lozenges, suppositories, reconstitutable powders, transdermal formulations, and aqueous and non-aqueous solutions.

5. A method of treating Attention Deficit Hyperactivity Disorder, ADHD, comprising administering to a person who would benefit a pharmaceutical composition comprising a compound according to Formula 1 :

Formula 1

and salts, racemates, and enantiomers thereof, wherein

Ri-Rt: are each independently selected from the group consisting of hydrogen and

Cι-C₆ substituted and unsubstituted, saturated and unsaturated alkyl groups; and further wherein the dotted lines represent either a bond or the absence of a bond, provided that the nitrogen atom is connected to the bicyclic moiety either directly at the 2-carbon, or indirectly through the propyl chain at the 1 -carbon, or both; with the proviso that Rj may be absent when the nitrogen atom is connected directly at the 2-carbon; and a pharmaceutically acceptable carrier.

6. The method according to claim 5, wherein said compound is Formula 2:

or a salt thereof.

7. The method according to claim 5, wherein said compound is Formula 3:

Formula 3

or a salt thereof.

8. The method according to claim 5, wherein said compound is Formula 4:

or a salt, racemate, or enantiomer thereof.

9. The method according to claim 5, wherein the salts are selected from the group consisting of hydrochlorides, hydrobromides, sulphates, methanesulphonates, nitrates, maleates, acetates, citrates, fumarates, tartrates, succinates, benzoates and amino acid salts.

10. The method according to claim 5, wherein said person is a juvenile.

11. The method according to claim 5, wherein the composition is administered daily.

12. The method according to claim 5, wherein said composition is co-administered with at least one additional active agent.

13. A method of treating hyperactivity-impulsivity associated with ADHD comprising administering to a person who would benefit a pharmaceutical composition comprising a compound according to Formula 1 :

Formula 1

and salts, racemates, and enantiomers thereof, wherein

R_I-P are each independently selected from the group consisting of hydrogen and

Cι-C₆ substituted and unsubstituted, saturated and unsaturated alkyl groups; and further wherein the dotted lines represent either a bond or the absence of a bond, provided that the nitrogen atom is connected to the bicyclic moiety either directly at the 2-carbon, or indirectly through the propyl chain at the 1 -carbon, or both; with the proviso that R_\ may be absent when the nitrogen atom is connected directly at the 2-carbon; and a pharmaceutically acceptable carrier.

14. A method of treating inattention associated with ADHD comprising administering to a person who would benefit a pharmaceutical composition comprising a compound according to Formula 1 :

Formula 1

and salts, racemates, and enantiomers thereof, wherein

R₁-R₄. are each independently selected from the group consisting of hydrogen and

Cι-C₆ substituted and unsubstituted, saturated and unsaturated alkyl groups; and further wherein the dotted lines represent either a bond or the absence of a bond, provided that the nitrogen atom is connected to the bicyclic moiety either directly at the 2-carbon, or indirectly through the propyl chain at the 1 -carbon, or both; with the proviso that R] may be absent when the nitrogen atom is connected directly at the 2-carbon; and a pharmaceutically acceptable carrier.

15. A method of making a pharmaceutical composition for the treatment of ADHD comprising combining the compound according to Formula 1 of claim 5, or a salt thereof, with a pharmaceutically acceptable carrier.

16. The method according to claim 15, wherein the pharmaceutically acceptable carrier is selected from the group consisting of suspensions, tablets, capsules, powders, granules, lozenges, suppositories, reconstitutable powders, transdermal formulations, and aqueous and non-aqueous solutions.

17. A method of treating ADHD comprising administering to a person who would benefit a pharmaceutical composition comprising a compound that is a 5-HT1A agonist/5HT2 antagonist and a pharmaceutically acceptable carrier.

18. The method according to claim 5, wherein the administered amount of compound according to Formula 1 is about 0.01 mg/kg/day to about 100 mg/kg/day.

19. The method according to claim 5, wherein the administered amount of compound according to Formula 1 is about 0.3 mg/kg/day to about 30 mg/kg/day.

20. The method according to claim 5, wherein the administered amount of compound according to Formula 1 is about 0.5 mg/kg/day to about 5 mg/kg/day.

21. The method according to claim 5, wherein the administered amount of compound according to Formula 1 is about 0.75 mg/kg/day to about 3 mg/kg/day.

22. The method according to claim 5, wherein R j are each independently selected from the group consisting of hydrogen and Cι-C₆ unsubstituted-and- saturated alkyl groups.

23. The method according to claim 5, wherein the nitrogen atom is connected to the bicyclic moiety indirectly through the proply chain at the 1 -carbon.