AU3675299A - Methods and compositions for treating emesis, nausa and other disorders using optically pure R(+) ondansetron - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority *o Related Art: c.

C* Name of Applicant: Sepracor, Inc.

Actual Inventor(s): James W. Young Address for Service: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: METHODS AND COMPOSITIONS FOR TREATING EMESIS, NAUSA AND OTHER DISORDERS USING OPTICALLY PURE ONDANSETRON Our Ref 589385 POF Code: 1443/70025 The following statement is a full description of this invention, including the best method of performing it known to applicant(s):

RECEIVED

2 5 JUN 1999

MELBOURNE

I 1A METHODS AND COMPOSITIONS FOR TREATING EMESIS, NAUSEA AND OTHER DISORDERS USING OPTICALLY PURE ONDANSETRON The present application is a divisional application from Australian patent application number 70398/96, the entire disclosure of which is incorporated herein by reference.

1. BACKGROUND OF THE INVENTION This invention relates to novel compositions of matter containing optically pure ondansetron. These novel compositions have potent antiemetic activity S and are useful in ameliorating the nausea and vomiting otherwise induced by cancer chemotherapeutic agents and higher dose radiotherapeutic treatment 15 procedures while avoiding adverse effects including but not limited to headache, constipation and increases in transaminase levels, which are associated with the administration of the racemic mixture of ondansetron. Additionally, these novel compositions of matter containing optically pure ondansetron are useful in treating behavioural disorders such as mood anxiety and schizophrenia, and such 20 other conditions as may relate to ondansetron's activity as a competitive antagonist of serotonin receptor subtype 5-HT 3 including but not limited to disorders of gastrointestinal motility, depression, migraine, alcohol, nicotine or drug (benzodiazepine et al.) withdrawal, while avoiding adverse effects associated with the administration of the racemic mixture of ondansetron.

Furthermore, these novel compositions of matter containing optically pure ondansetron are useful in treating cognitive disorders such as dementia and ageassociated memory impairment, while avoiding the adverse effects associated with the administration of the racemic mixture of ondansetron. Also disclosed are methods for treating the above described conditions in a human while avoiding the adverse effects that are associated with the racemic C:\WINWORD\KATEL\MARGARET\PDV70398.DOC 1k -2mixture of ondansetron, by administering the isomer of ondansetron to said human.

The active compound of this composition, and method is an optical isomer of the compound, ondansetron which is described in United States Patent No. 4,695,578.

Chemically, the active compound is the isomer of 1,2,3,9-tetrahydro-9-methyl-3-[( 2 -methyl-l

H

-imidazol-lyl)methyl]-4H-carbazol-4-one. This isomer will hereinafter be referred to as ondansetron.

1.1. Steric Relationships and Drug Action Many organic compounds exist in optically active forms, they have the ability to rotate the plane of plane-polarized light. n describing an optically active 15 compound, the prefixes D and L or R and S are used to denote the absolute configuration of the molecule about its chiral center(s). The prefixes and or d and 1 .:are employed to designate the sign of rotation of planepolarized light by the compound, with or I meaning that the compound is levorotatory. A compound prefixed with or d is dextrorotatory. For a given chemical structure, these compounds, called stereoisomers, are identical except that they are mirror images of one another. A specific stereoisomer may also be referred to as an enantiomer, and a mixture of such isomers is often called an enantiomeric or racemic mixture.

Stereochemical purity is of importance in the field of pharmaceuticals, where 12 of the 20 most prescribed drugs exhibit chirality. A case in point is provided by the L-form of the 0-adrerergic blocking agent, propranolol, which is knc n to be 100 times more potent than the D-enantiomer.

Furthermore, optical purity is important since certain isomers may actually be deleterious rather than simply inert. For example, it has been suggested that the u -3- D-enantiomer of thalidomide was a safe and effective sedative when prescribed for the control of morning sickness during pregnancy, and that the corresponding

L-

enantiomer, a potent teratogen.

Ondansetron, which is the subject of the present invention, is available commercially only as the 1:1 racemic mixture; it is a mixture of optical isomers, called enantiomers. The racemic mixture of ondansetron is a dihydrate, that is administered as a hydrochloride salt.

The enantiomers of ondansetron are disclosed in Butler et al., Br. J. Pharmacol., 94, pg. 397-412 (1988). This reference states that the R and S isomers of ondansetron were approximately equipotent as 5-HT antagonists on rat vagus nerve. Furthermore, the reference alleges that the 15 racemic mixture caused concentration-dependent parallel rightward displacement of the 2-methyl -5-HT concentration response curve when exposed to the longitudinal smooth muscle of the guinea-pig ileum, and that the R isomer was more potent than the S isomer when administered competitively against The racemic mixture of ondansetron is an antagonist of the 5-hydroxytryptamine (5-HT 3 or serotonin) receptor.

The role of serotonin, and thus the pharmacology of ondansetron has been broadly implicated in a variety of conditions for marry years (see, Phillis, The Pharmacology of Synapses, Pergamon Press, Monograph 43, 1970; Frazer, A. et al. Annual Rev. of Pharmacology and Therapeutics 30, 307-348, 1990). Thus, research has focused on locating the production and storage sites of serotonin as well as the location of serotonin receptors in the human body in order to determine the connection between these sites and various disease states or conditions.

In this regard, it was discovered that a major site of production and storage of serotonin is the i' -4enterochromaffin cell of the gastrointestinal mucosa. It was also discovered that serotonin has a powerful stimulating action on intestinal motility by stimulating intestinal smooth muscle, speeding intestinal transit, and decreasing absorption time, as in diarrhea. This stimulating action is also associated with nausea and vomiting.

Thus, researchers studied diseases and treatment of diseases where the above described effects were manifested. One such treatment is chemo-and radio-therapy of cancer using chemotherapeutic and high dose radiotherapeutic agents. Chemo-and radio-therapy may induce nausea and vomiting by the release of serotonin from damaged enterochromaffin cells in the 15 gastrointestinal tract. Release of the neurotransmitter serotonin, stimulates both afferent vagal nerve fibers (thus initiating the vomiting reflex) and serotonin receptors in the chemoreceptor trigger zone of the area S: postrema region of the brain.

One of the first agents used to prevent the nausea and vomiting associated with emetogenic cancer chemotherapy was metoclopramide. This compound is an antagonist of central and peripheral dopamine receptors, and at high doses it also antagonizes serotonin receptors.

25 Because it had this combined effect, researchers began to search for a more specific and safer serotonin antagonist to use to treat nausea and vomiting associated with chemo-and radio-therapy of cancer. This led to the development of ondansetron.

Ondansetron is a competitive antagonist at serotonin 5-HT 3 receptor subtypes in both the gastrointestinal tract and the brain, where it blocks both sites of serotonin-induced emesis. With respect to its anti-emetic potential, ondansetron appears to offer a dual mode of action through antagonism of serotonin at peripheral vagal nerve afferents, and antagonism of serotonin within the central nervous system, at or near the chemoreceptor trigger zone.

Consequently, ondansetron may produce a significant reduction, or a complete inhibition of nausea and vomiting in the majority of patients subsequently treated with cancer chemotherapeutics of moderate or high emetic potential. Similarly, the compound prevented radiationinduced nausea and emesis. Further, ondansetron appears Sto have an effect on gastrointestinal motility slowing the •.transit of material through portions of the tract. This decrease in motility may be beneficial in those patients undergoing the chemotherapy for cancer where diarrhea can provide an additional debilitating burden.

Ondansetron's use as an antiemetic by either the *'"':intravenous or oral routes is disclosed in U.S. Patent No.'s 4,753,789 and 4,929,632 Furthermore, various researchers have tested the use of the racemic mixture of ondansetron to prevent nausea and vomiting caused by anticancer chemotherapy. See, Green et al., Cancer Chemother. Pharmacol. 24:137-139 (1989); Cubeddu et al., New Eng. J. Med., Vol. 322; No. 12, pg. 810-815 (1990); "De Mulder et al., Ann. Int. Med., Vol. 113: No. 11, pg.

5 834-840 (1990); Marty, Eur. J. Cancer Clin. Oncol., Vol.

25, Suppl. 1, pg. 541-545 (1989); Khojasteh et al., Cancer, Vol. 66, No. 6, pg. 1101-1105 (1990); Schmoll, Eur. Cancer Clin. Oncol, Vol. 25, Suppl. 1, pg. 535- 539 (1989); Grunberger et al., J. Cli. Oncl±, Vol. 7, No. 8, pg. 1137-1141 (1989); Kris et al., j. Cli. Oncol, Vol. 6, no. 4, pg. 659-662 (1988).

Thus, in the context of adjunctive therapy for cancer treatment, ondansetron appears to be an effective antiemetic, although its dose-response relationships remain to be clarified The drug offers a moderate potency, a half-life of some three hours, and the -6potential for prophylactic/therapeutic activity. Dosing 1-2 hours prior to cancer therapy or at the initiation of therapy can be accomplished by continuous infusion, or repeated oral or intravenous administrations. (see Smith, Safety of Ondansetron, European J. of Cancer and Clinical Oncology, 25 Suppl.l 547-50, 1989; and Smyth, J.F. ibid., 555-57, 1989).

As stated previously, stimulation of serotonin receptors has been postulated to be involved in a variety of disease states and conditions. Thus, it has been proposed that antagonizing serotonin receptors will assist in treating these conditions.

It has been proposed that the racemic mixture of .ondansetron is useful in the treatment of anxiety disorders. Anxiety disorder has its etiology in both Psychologic and physiologic factors, and it has been suggested that a genetic influence exists. Emotional stress can precipitate anxiety neurosis which represents the individual's fear of losing control of such emotional drives as aggression or dependency needs, and losing control of :ne's resulting actions. Physiologically anxiety is ssociated with autonomic nervous system .discharge, .nd related neurohumoral processes. In acute anxiety attacks, lasting from afew minutes to an hour, the individual experiences a subjective sense of terror, for no evident reason, and perhaps a haunting dread of catastrophe. Chronic anxiety displays less intense sym oms of longer duration, characterized by uneasiness, nervousness, nagging uncertainty about future events, headache, fatigue and subacute autonomic symptoms. The use of the racemic mixture of ondansetron to treat anxiety disorders is disclosed in U.S. Patent No. 4,695,578.

It has also been proposed that the racemic mixture of ondansetron is useful to treat psychotic disorders such as schizophrenia. (See U.S. Patent No. 4,695,578).

Schizophrenic disorders are complex mental disorders which tend toward chronicity, and which impair functioning, and are characterized by psychotic symptoms of disturbed thinking, feeling and general behavior. Clear, goal directed thought becomes difficult, while blunting and inappropriate affect become the most characteristic emotional changes. Auditory hallucinations can be common, and delusions of persecution are frequent, as are threats of violence, and minor aggressive outbursts. Disturbances of movement can range from significant over-activity and excitement to retardation and stupor. Treatment has often included tranquilizer and other antipsychotic drugs, administered orally or by long acting depot injections (to offset problems of patient compliance).

15 The racemic mixture of ondansetron has also been proposed to be useful in the treatment of depression (see U.S. Patent No. 4,835,173). Depression, an affective ~disorder, is characterized by changes in mood, as a •primary clinical feature. The most common of the significant mental illnesses, depression must be distinguished clinically from periods of normal grief, sadness, and disappointment, and the related dysphoria or demoralization frequently associated with medical illness.

Depression is characterized by feelings of intense sadness, and despair, mental slowing and loss of concentration, pessimistic worry, agitation, and selfdeprecation. Physical changes can also occur, including insomnia, anorexia, and weight loss, decreased energy and libido, and the disruption of circadian rhythms. Often the condition responds well to tricyclic or related antidepressant drugs, monoamine oxidase inhibitors, or in resistant cases or severe disease, to electro-convulsive shock treatment. Nevertheless, the treatment of depression would benefit from new therapy.

-8- It has also been proposed that the racemic mixture of ondansetron is useful to treat migraine (see U.S.

Patent No. 4,695,578). Migraine is of unknown cause, although evidence suggests a functional disturbance of the cranial circulation. The condition is a paroxysmal disorder, characterized by recurrent attacks of headache, which can be associated with visual and gastrointestinal disturbances. Migraine headaches may be preceded by a short period of depression, irritability, restlessness or anorexia.

U.S. Patent No. 4,847,281 discloses the use of the racemic mixture of ondansetron to treat substance abuse.

Disorders of substance use or abuse often involve both psychologic and physical dependence, accompanied by the *15 development of tolerance (the need to increase the dose progressively so as to produce the effect originally achieved by smaller amounts), and manifested by a withdrawal or abstinence syndrome.

Alcohol withdrawal syndrome represents a continuum 20 of symptoms including tremor, weakness, sweating and Sgastrointestinal symptoms usually beginning some hours after cessation of intake. Drugs which alter the serotonin system can modulate the alcohol consumption in 2humans. Some mutual, but incomplete cross-tolerance exists between alcohol and other drugs including the benzodiazepines, the sedative-hypnotic, and the anxiolytic muscle relaxant group. While benzodiazepine withdrawal symptoms are often considered moderate, in withdrawal often anxiety returns, with dysphoria irritability, sweating, headache and sleep abnormalities. Nicotine withdrawal syndrome following cessation of tobacco use, varies significantly among subjects in intensity, and specific signs and symptoms. Apart from the craving for tobacco products, which begins within 24 hours of cessation and then subsides over a period of some days, -9other symptoms include, but are not limited to, irritability, anxiety, increased appetite and the gastrointestinal symptoms, and inability to concentrate.

In addition, the racemic mixture of ondansetron could be useful in the treatment of cognitive disorders.

Cognitive disorders include but are not limited to dementia and age-associated memory impairment.

Dementia can occur at any age. It is a structurally caused permanent or progressive decline in several dimensions of intellectual function that interferes substantially with individual normal social or economic activity.

One particular type of dementia is Alzheimers-type .dementia. Alzheimers-type dementia is thought to be due 15 to a degenerative process, with a large loss of cells from the cerebral cortex and other brain areas. Acetylcholinetransmitting neurons and their target nerve cells are particularly affected. The brain shows marked atrophy with wide sulci and dilated ventricles. Senile plaques and neurofibrillary tangles are present. Memory loss is the most prominent early symptom. Disturbances of arousal do not occur early in the course. Alzheimer's presenile S. and senile onset dementias are similar in both clinical Sand pathologic features, with the former commonly beginning in the 5th and 6th decades and the latter in the 7th and 8th decades. The dementia usually progresses steadily, becoming well advanced in 2 to 3 years. Some cases of dementia occurring in the presenile period are hard to classify and are sometimes labelled idiopathic or simple presenile dementia.

The signs and symptoms of dementia, in particular Alzheimers-type dementia, include depression, paranoia, anxiety or any of several other psychologic symptoms. The Smost common clinical picture is slow disintegration of personality and intellect due to impaired insight and judgment and loss of affect. Memory impairment increases, beginning with problems recalling recent events or finding names. The impairment varies greatly from time to time and often from moment to moment. Dementia generally is an insidious, slowly progressive, untreatable condition.

However, the rate of progression varies widely and depends on the cause.

Another type of cognitive disorder is ageassociated memory impairment (AAMI). AAMI is used to describe healthy non-demented people who have experienced memory loss over the course of the person's life. Most :commonly it is used to describe adults over the age of who have experienced memory loss over the course of adult life. It has been estimated that between 25% and 50% of 15 people over the age of 65 have this disorder.

While the racemic mixture of ondansetron offers Sefficacy in treating a variety of diseased states and conditions, its use is associated with adverse effects (principally headache and constipation) which increase 20 with the dose of the racemic mixture of ondansetron administered.

Thus it would be particularly desirable to find a compound with the advantages of ondansetron which would not have the aforementioned disadvantages.

2. SUMMARY OF THE INVENTION It has now been discovered that the optically pure isomer of ondansetron is an effective anti-emetic agent, useful as an adjunctive therapy in cancer treatment to ameliorate nausea and vomiting induced by chemo- or radio-therapeutics, while decreasing the usual adverse effects including, but not limited to, headache, constipation and increases in transaminase levels which Sare associated with the racemic mixture of ondansetron.

It has also been discovered that the optically pure -11isomer of ondansetron is a useful agent to treat such behavioral disorders as mood anxiety and schizophrenia, and such other conditions as may relate to the composition's activity as a competitive antagonist at serotonin receptor subtype 5-HT 3 such as disorders of gastrointestinal motility, depression, migraine, and as a therapeutic aid in alcohol, nicotine, and benzodiazepine withdrawal, while decreasing the usual adverse effects associated with the racemic mixture of ondansetron.

Furthermore, it has also now been discovered that the optically pure isomer of ondansetron is useful in treating cognitive disorders such as dementia and ageassociated memory impairment, while decreasing the adverse effects associated with the racemic mixture of 15 ondansetron.

The present invention also includes novel compositions of matter, containing optically pure ondansetron which are useful and effective as antiemetic adjunctive therapy in cancer treatment by chemo-or radiotherapeutics, and as agents for the aforementioned disorders. These novel compositions also avoid, or reduce the above described adverse effects associated with the administration of the racemic mixture of ondansetron.

Thus, with the isomer of ondansetron, clearer dose 25 definitions of efficacy vis a vis adverse effects, may be achieved.

3. DETAILED DESCRIPTION OF THE INVENTION The present invention encompasses a method of eliciting an antiemetic effect while avoiding the concomitant liability of adverse effects which comprises administering to a human in need of such antiemetic therapy an amount sufficient to alleviate nausea and Svomiting, but insufficient to cause said adverse effects, -12of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

The present invention also encompasses an antiemetic composition for the treatment of a human in need of antiemetic therapy, which comprises an amount sufficient to alleviate nausea and vomiting but insufficient to cause adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

The present invention further encompasses a method of treating behavioral disorders such as mood anxiety or .6 schizophrenia in a human while avoiding the concomitant liability of adverse effects, which comprises administering to said human in need of such therapy, an *15 amount sufficient to alleviate said condition, but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

:In addition, the present invention encompasses a composition for the treatment of a human with behavior disorders such as mood anxiety or schizophrenia, which comprises an amount sufficient to alleviate behavioral disorders such as mood anxiety or schizophrenia, but :insufficient to cause adverse effects, of 25 ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

Also included in the present invention is a method of treating a condition caused by disturbance of neuronal function while avoiding the concomitant liability of adverse effects, which comprises administering to a human in need of such therapy an amount sufficient to alleviate said condition but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer. Conditions caused by a disturbance of -13neuronal 5-HT function include but are not limited to, disorders of gastrointestinal motility, depression, migraine, and alcohol, nicotine, or drug (benzodiazepine et al.) withdrawal.

A further aspect of the present invention is a composition for treating a condition caused by disturbance of neuronal 5-HT function, which comprises an amount sufficient to alleviate said condition but insufficient to cause adverse effects, of ondansetron, or a Pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

Furthermore, the present invention includes a Smethod of treating cognitive disorders such as dementia or age-associated memory impairment, while avoiding the concomitant liability of adverse effects, which comprises administering to a human in need of such therapy an amount sufficient to alleviate said cognitive disorder but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

S. A further aspect of the present invention is a :composition for treating cognitive disorders such as dementia or age-associated memory impairment, which comprises an amount sufficient to alleviate said condition, but insufficient to cause adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof., substantially free of its stereoisomer.

The available racemic mixture of ondansetron (i.e.

a 1:1 racemic mixture of stereoisomers) causes antiemetic 3 activity, and provides therapy and a reduction of symptoms in a variety of conditions and disorders; however this racemic mixture, while offering the expectation of efficacy, causes adverse effects. Utilizing the Sisomer of ondansetron alone results in dose related definitions of efficacy, diminished adverse effects, and -14accordingly, an improved therapeutic index. It is therefore, more desirable to use the isomer of ondansetron.

The term 'adverse effects' includes, but is not limited to headache, constipation, fatigue, sedation, lethargy, drowsiness, dry mouth, diarrhea and transient increases in transaminase levels. Increases in the serum activity of certain hepatocellular enzymes is also included within the term "adverse effects".

The term "substantially free of its stereoisomer" as used herein means that the composition contains a greater proportion of the isomer of ondansetron in relation to the isomer of ondansetron. Preferably the 10 composition contains at least 90% by weight of ondansetron, and 10% by Sweight or less of ondansetron. More preferably the composition contains at least 99% by weight ondansetron, and 1% or less of ondansetron.

The term, "eliciting an antiemetic effect" as used herein means providing relief from the symptoms of nausea and vomiting induced spontaneously or 15 substantially free of its associated with emetogenic cancer chemotherapy of irradiation therapy.

The term, "behavioral disorders such as mood anxiety, and schizophrenia" as used herein means relief from the symptoms which include, but are not limited to, a subjective sense of terror, a dread of catastrophe, uneasiness, nervousness uncertainty, headache, fatigue, disturbed thinking, inappropriate affect, auditory hallucinations, aggressive outbursts and the like.

The term, "a condition caused by disturbance of neuronal 5-HT function" includes but is not limited to C WIN VORO KATEL\KATE\MN'NODELETE\7O398 DOC disorders of gastrointestinal motility, depression, migraine and alcohol, nicotine or drug (benzodiazepine et al.) withdrawal. This includes relief from the symptoms which include, but are not limited to, diarrhea and related symptoms, as decreased absorption time, etc., intense sadness, despair, mental slowing, loss of concentration, worry, agitation, headache, irritability, restlessness, anorexia, sweating, sleep abnormalities, and the like.

S" 10 The term "treating cognitive disorders" as used .herein means providing relief from the symptoms of cognitive disorders including but not limited to memory loss, disintegration of personality and intellect, depression, paranoia, anxiety and other psychologic 15 symptoms.

The preparation of the mixture of enantiomers, racemic mixture) of ondansetron is disclosed in U.S. Patent No. 4,695,578. The isomer of ondansetron, may be obtained by resolution of the mixture of enantiomers of ondansetron using conventional means such as an optically active resolving acid; see, for example, "Stereochemistry of Carbon Compounds", by E.L.

Eliel (McGraw Hill 1962) and Lochmuller C.H. et al.,

J.

Chromatoqr., 1975, Vol. 113, No. 3, Pg. 283-302.

The magnitude of a prophylactic or therapeutic dose of ondansetron in the acute or chronic management of disease will vary with the severity of the condition to be treated, and the route of administration. The dose, and perhaps dose frequency, will also vary according to the age, body weight, and response of the individual patient.

In general, the total, daily dose ranges, for the conditions described herein, from about 0.01 mg to about mg administered in divided doses orally, or by a slow intravenous injection or infusion. In cases of moderate to highly emetogenic chemotherapy, it may be expected -16that, an initial loading dose of between about 2 mg to about 10 mg given by slow intravenous injection or infusion over 15-30 minutes, immediately before the emetogenic chemotherapy, and followed by about 2 mg to about 8 mg given orally every eight hours for periods up to four to five days will elicit therapy and provide for a reduction of symptoms. In cases of radiotherapy, and as an oral therapeutic for the other conditions described herein, generally doses of between about 2 mg to about 10 8 mg orally every eight hours, should provide benefit to adult patients. In the case of using ondansetron to treat cognitive disorders such as dementia and ageassociated memory impairment, the total daily dosage ranges may be from about 0.001 mg to about 35 mg in divided doses orally or by a slow intravenous injection or infusion. Children generally will benefit from doses that are generally some 25-50 percent those of the adult for a given condition, while geriatric patients generally tolerate adult doses. It may be necessary to use dosages outside these ranges in some conditions.

The term, "an amount sufficient to alleviate the nausea and vomiting but insufficient to cause said adverse effects" is encompassed by the above described dosage amounts and dose frequency schedule. In addition, the term "an amount sufficient to alleviate said condition but insufficient to cause said adverse effects" wherein said conditions include but are not limited to behavioral disorders such as mood anxiety and schizophrenia as well as disturbances of neuronal 5-HT function including, but not limited to, disorders of gastrointestinal motility, depression, migraine and alcohol, nicotine or drug (benzodiazepine et al.) withdrawal are also encompassed by the above described amounts. The term "an amount sufficient to alleviate said condition but insufficient to cause said adverse effects" wherein said condition

I

-17includes cognitive disorders such as dementia and ageassociated memory impairment, is also encompassed by the above-described amounts.

Any suitable route of administration may be employed for providing the patient with an effective dosage of ondansetron. For example, oral, rectal, parenteral, transdermal, subcutaneous, intramuscular, and the like may be employed. Dosage forms include tablets, troches, dispersions, suspensions, solutions, capsules, 10 patches, and the like.

The pharmaceutical compositions of the present invention comprise ondansetron as active ingredient, .or a pharmaceutically acceptable salt thereof, and may also contain a pharmaceutically acceptable carrier, and 15 optionally, other therapeutic ingredients. The term "pharmaceutically acceptable salts" refers to salts prepared from pharmaceutically acceptable non-toxic acids including inorganic acids and organic acids.

ince the compound of the present invention is basic, salts may be prepared from pharmaceutically acceptable non-toxic acids including inorganic and organic acids. Such acids include acetic, benzene-sulfonic, benzoic camphorsulfonic, citric, ethenesulfonic, fumaric, gluconic, glutamic, hydrobromic, hydrochloric, isethionic, lactic, maleic, malic, mandelic, methanesulfonic, mucic, nitric, pamoic, pantothenic, phosphoric, succinic, sulfuric, tartaric acid, p-toluenesulfonic, and the like.

Particularly preferred are hydrobromic, hydrochloric, phosphoric and sulfuric acids.

The compositions include compositions suitable for oral, rectal or other mucosal routes, transdermal, parenteral (including subcutaneous, intramuscular, and intravenous), although the most suitable route in any Sgiven case will depend on the nature and severity of the condition being treated. The most preferred routes of the -18present invention include both intravenous injections, and infusions and the oral route. They may be conveniently presented in unit dosage form, and prepared by any of the methods well known in the art of pharmacy.

In the case where an oral composition is employed, a suitable dosage range for use is, from about 5 mg to about 35 mg total daily dose, administered as equally divided doses, three times a day. Preferably, a dose range of between about 10 mg to about 30 mg per day, administered as equally divided doses, three times a day, ,and most preferably from between about 12 mg to about 24 mg per day, administered as equally divided doses, three Stimes a day. Patients may be upwardly titrated within this dose range to enable the satisfactory control of symptoms. In the case where an oral composition is employed to treat cognitive disorders such as dementia and age-associated memory impairment, a suitable dosage range for use is from about 0.001 mg to about 35 mg total daily administered as equally divided doses from one to three times a day. Preferably a dose range of between about 0.001 mg to about 20 mg per day administered as *S ~equally divided doses one to three times a day and most preferably from between 0.001 mg to about 10 mg per day administered as equally divided doses, one to three times a day.

In the case where an intravenous injection or infusion composition is employed, a suitable dosage range for use is, e.g. from about 0.01 mg to about 32 mg total daily dose, presented as a loading slow intravenous injection of about 2 mg to about 8 mg over 15-30 minutes, followed by an intravenous infusion of about 0.5 mg to about 1.0 mg/hour for up to 24 hours. These regimens may be followed by oral doses of between about 1.5 mg to about mg every eight hours for periods up to five days.

_19- In practical use, ondansetron can be combined as the active ingredient in intimate admixture with a pharmaceutical carrier according to conventional pharmaceutical compounding techniques. The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g. oral or parenteral (including intravenous injections or infusions). in preparing the compositions for oral dosage form, any of the usual pharmaceutical media may be employed, water, glycols, oils, alcohols, flavoring aetpreservativesclrn agents, and the like in the case of oral liquid preparations, suspensions, solutions, and elixirs; or aerosols; or carriers such as starches, sugars, mir-rsaln cellulose, diluents, granulating agents, lubricants, binders, disintegrating agents, and the like in the case of oral solid prprain podes capsules, n tablets, wt the solid oral preparations being. preferred over the liquid preparations. The most preferred solid oral preparation is tablets.

0. Because of their ease of amnsrtotablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are :employed. if desired, tablets may be coated by standard aqueous or nonaqueous techniques.

In addition to the common dosage forms set out above,the compounds of the present invention may also be administered by controlled release means and/or delivery devices such as those described in U.S. Patent Nos.: 3,845,770; 3,916,899; 3,536,809; 3,598,123; and 4,008,719, the disclosures of which are hereby incorporated by reference.

Another preferred route of administration, particularly to avoid problems associated with emesis, is -j transdermal delivery, for example, via an abdominal skin patch.

Pharmaceutical compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets, or aerosol sprays, each containing a predetermined amount of the active ingredient as a powder or granules, or as a solution or a suspension in an aqueous liquid, a non-aqueous liquid, an oil-in-water emulsion, or a water-in-oil liquid emulsion. Such compositions may be prepared by any of the methods of pharmacy, but all methods include the step of bringing into association, the active ingredient with the carrier which constitutes one or more necessary ingredients. In 15 general, the compositions are prepared by uniformly and intimately admixin the active ingredient with liquid carriers or finely divided solid carriers or both and p then, if necessary, shaping the product into the desired presentation.

20 For example, a tablet may be prepared by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared by compressing in a suitable machine, the active 2 ingredient in a free-flowing form such as powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active or dispersin d g agent Molded tablets may be made by molding in a suitable machine, a mixture of the powdered compound, moistened with an inert liquid diluent. Desirably, each tablet contains from about 2.0 mg to about 8.0 mg of the active ingredient, and each cachet or capsule contains from about 2.0 mg to about mg. of the active ingredient. Most preferably, the tablet, cachet or capsule contains either one of three dosages: 2.0 mg, 4.0 mg and 8.0 mg (as scored tablets, the preferable dose form) of active ingredient.

-21- Furthermore, each tablet or capsule can contain from about 0.001 mg to about 10.0 mg of the active ingredient.

However, the amount of active ingredient found in the composition may vary depending on the amount of active ingredient to be administered to the patient.

The invention is further defined by reference to the following examples describing in detail, the preparation of the compound, and the compositions of the present invention. It will be apparent to those skilled in the art, that many modifications, both to materials and methods, may be practiced without departing from the purpose and interest of this invention.

All temperatures are in degrees Celsius.

4. EXAMPLES 4.1. EXAMPLE 1 A pharmacological study to determine the relative 20 potency and specificity of optically pure ondansetron and racemic ondansetron as competitive antagonists at serotonin receptor subtype 5-HT 3 present in gastrointestinal, brain, and other tissues.

The optically pure and racemic compounds may be evaluated as a function of their molar concentration, for their relative abilities to inhibit the binding of 3 in such selected preparations as nerves of guinea pig ileum and preparations of brain tissue from several species including rats and humans. The availability of 3H- 5-HT as a radioligand with relatively high specific activity, the development of other selective 5-HT 3 antagonists, and the additional agonist, hydroxy-tryptamine 2 -methyl-5-HT) provide the Spharmacologic tools for the characterization of the 5-HT 3 receptor, and the evaluation of and racemic -22ondansetron. (see Frazer, et al., Annu. Rev.

Pharmacol. Toxicol. 30, 307-348, 1990). It has been suggested, (Bradley, P.B et al., Neuropharmacology 563-576, 1986) as part of the evolving characterization of serotonin receptor subtypes, that responses mediated by

HT

3 receptors: be reduced by selective antagonists, not be inhibited by selective antagonists of other subtypes of serotonin receptors, and be mimicked by 2-methyl 5-HT at concentrations comparable to that of serotonin.

Accordingly, the comparative ability of and racemic ondansetron, to inhibit the binding of 3H-5-HT and the agonist, 3H-2-methyl 5-HT, not to be inhibited as a radioligand for 5-HT3 receptors by selective antagonists of other subtypes and to be inhibited from selective binding as a function of concentration, by other 5-HT 3 selective antagonists of possibly greater potency including Szacopride ICS 205-930, and granisetron, will serve a characterization of potency and specificity at 5-HT 3 receptors.

-23- 4.2. EXAMPLE 2: ORAL FORMULATION Tablet: Formula Quantity per Tablet in mg Active Ingredient B ondansetron 2.0 4.0 L a ct o s e B P :e BP 151.5 149.5 145.5 Starch BP 30.0 30.0 30.0 Pregelatinized Maize Starch BP 15.0 15.0 15.0 1 5 .0 15.0 Magnesium Stearate

BP

1.5 Compression Weight 2000 200.0 200.0 S 200 .0 .e e The active ingredient, is sieved through a suitable sieve and blended with lactose, starch, and pregeatinised maize starch. Suitable volumes of purified water are added and the powders are granulated. After drying, the granules are screened and blended with the magnesium stearate. The granules are then compressed into tablets using 7 mm diameter punches.

Tablets of other strengths may be prepared by altering the ratio of active ingredient to lactose or the compression weight and using punches to suit.

-24- 4-3. EXAMPLE 3 ORAL FORMULATION Capsules: Formula Mg/capsule Active Inlgredient A

BC

ondansetron Starch .1500 M~agnesium Stearate

BP

27.0 97.0 4.0 Com re si n ei ht100.0 100.0 100.0 The active ingredient is sieved and blended with the excipients. The mix is filled into size NO. 2 hard gelatin capsules using suitable machinery- Other doses may be prepared by altering the fill weight an if necessary changing the capsule size to suit.

4.4. EXAMPLE 4 INTRAVENOUS

FORMULATION

Formula g /ml Active Ingredient ondansetron 400 Dilute Hydrochloric Acid BP to pH Sodium Chloride Injection BP 1 mi

S•

Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps.

S

S.oS 5*: S Document 3

Claims (102)

1. A method of eliciting an antiemetic effect while avoiding the concomitant liability of adverse effects, which comprises administering to a human in need of antiemetic therapy, an amount sufficient to alleviate nausea and vomiting, but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer. 10

2. A method according to claim 1, wherein ondansetron hydrochloride is administered.

3. A method according to either claim 1 or 2, wherein the ondansetron or pharmaceutically acceptable salt thereof, substantially free of its 15 stereoisomer is administered together with a pharmaceutically acceptable carrier.

4. A method according to any one of claims 1 to 3, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 20 by weight of total ondansetron.

A method according to claim 4, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

6. A method according to any one of claims 1 to 5, wherein ondansetron is administered by intravenous infusion, transdermal delivery, or orally as a tablet or a capsule.

7. A method according to any one of claims 1 to 6, wherein the amount administered is about 0.01 mg to about 35.0 mg. 27

8. A method according to claim 7, wherein the amount administered by intravenous infusion is about 2 mg to about 10 mg.

9. A method according to claim 7, wherein the amount administered orally is about 10.0 mg to about 30.0 mg.

A method according to claim 9, wherein the amount administered orally is about 12.0 mg to about 24.0 mg.

11. An antiemetic composition adapted for the treatment of a human in need of antiemetic therapy which comprises an amount sufficient to alleviate nausea and vomiting, but insufficient to cause adverse effects, of :00. ondansetron or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer, and a pharmaceutically acceptable carrier.

12. A composition according to claim 11 which comprises ondansetron hydrochloride.

13. A composition according to either claim 11 or 12 wherein the amount of ondansetron or pharmaceutically acceptable salt is at least by weight of total ondansetron.

14. A composition according to any one of claims 11 to 13 wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

A composition according to any one of claims 11 to 14, adapted for oral administration.

16. A composition according to any one of claims 11 to 14, adapted for intravenous delivery. 28

17. A composition according to any one of claims 11 to 14, adapted for use in a transdermal delivery formulation.

18. A composition according to claim 17, adapted for use as a transdermal patch.

19. A method of eliciting an antiemetic effect while avoiding the concomitant liability of adverse effects which comprises administering to a human in need of antiemetic therapy a composition according to any one of claims 11 to 18 in an amount of about 2.0 mg to about 8.0 mg.

20. A method according to claim 19, wherein said composition is administered from one to four times a day.

21. A method according to claim 20, wherein said composition is administered twice a day.

22. A method according to claim 21, wherein said composition is administered once a day.

23. A method of treating behavioural disorders such as mood anxiety and schizophrenia while avoiding concomitant liability of adverse effects, which comprises administering to a patient in need of such therapy, an amount sufficient to alleviate said condition, but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer.

24. A method according to claim 23, wherein ondansetron hydrochloride is administered.

A method according to either claim 23 or 24, wherein the ondansetron or pharmaceutically acceptable salt thereof, substantially free of its 29 stereoisomer is administered together with a pharmaceutically acceptable carrier.

26. A method according to any one of claims 23 to 25, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron.

27. A method according to claim 26, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron. 9*

28. A method according to any one of claims 23 to 27, wherein ondansetron is administered by intravenous infusion, transdermal delivery, or orally as a tablet or a capsule.

29. A method according to any one of claims 23 to 28, wherein the amount administered is about 0.01 mg to about 35.0 mg.

30. A method according to claim 29, wherein the amount administered by intravenous infusion is about 2 mg to about 10 mg.

31. A method according to claim 29, wherein the amount administered orally is about 10.0 mg to about 30.0 mg.

32. A method according to claim 31, wherein the amount administered orally is about 12.0 mg to about 24.0 mg.

33. A composition for the treatment of a human with behaviour disorders such as mood anxiety or schizophrenia, which comprises an amount sufficient to alleviate said behaviour disorders such as mood anxiety or schizophrenia, but insufficient to cause adverse effects, of ondansetron or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer, and a pharmaceutically acceptable carrier.

34. A composition according to claim 33 which comprises ondansetron hydrochloride.

A composition according to either claim 33 or 34 wherein the amount of ondansetron or pharmaceutically acceptable salt is at least by weight of total ondansetron.

36. A composition according to any one of claims 33 to 35 wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at .least 99% by weight of total ondansetron.

37. A composition according to any one of claims 33 to 36, adapted for oral administration.

38. A composition according to any one of claims 33 to 36, adapted for intravenous delivery.

39. A composition according to any one of claims 33 to 36, adapted for use in a transdermal delivery formulation.

A composition according to claim 39, adapted for use as a transdermal patch.

41. A method of treating behavioural disorders such as mood anxiety and schizophrenia while avoiding the concomitant liability of adverse effects which comprises administering to a human in need of such therapy a composition according to any one of claims 33 to 40 in an amount of about 2.0 mg to about mg. 31

42. A method according to claim 41, wherein said composition is administered from one to four times a day.

43. A method according to claim 42, wherein said composition is administered twice a day.

44. A method according to claim 43, wherein said composition is administered once a day.

45. A method of treating a condition caused by disturbance of neuronal o 5-HT function, while avoiding the concomitant liability of adverse effects, which comprises administering to a human in need of such therapy an amount sufficient to alleviate said condition but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically aceptable salt thereof, substantially free of its stereoisomer.

46. A method according to claim 45, wherein ondansetron hydrochloride is administered.

47. A method according to either claim 45 or 46, wherein the ondansetron or pharmaceutically acceptable salt thereof, substantially free of its stereoisomer is administered together with a pharmaceutically acceptable carrier.

48. A method according to any one of claims 45 to 47, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron.

49. A method according to claim 48, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

S 32 A method according to any one of claims 45 to 49, wherein ondansetron is administered by intravenous infusion, transdermal delivery, or orally as a tablet or a capsule.

51. A method according to any one of claims 45 to 50, wherein the amount administered is about 0.01 mg to about 35.0 mg.

52 A method according to claim 51, wherein the amount administered by intravenous infusion is about 2 mg to about 10 mg.

53. A method according to claim 51, wherein the amount administered orally is about 10.0 mg to about 30.0 mg.

54. A method according to claim 53, wherein the amount administered orally is about 12.0 mg to about 24.0 mg.

55. A composition for treating a condition caused by disturbance of neuronal 5-HT function, which comprises an amount sufficient to alleviate said condition, but insufficient to cause adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer and a pharmaceutically acceptable carrier.

56. A composition according to claim 55 which comprises ondansetron hydrochloride.

57. A composition according to either claim 55 or 56 wherein the amount of ondansetron or pharmaceutically acceptable salt is at least by weight of total ondansetron.

58. A composition according to any one of claims 55 to 57 wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

59. A composition according to any one of claims 55 to 59, adapted for oral administration.

A composition according to any one of claims 55 to 59, adapted for intravenous delivery.

61. A composition according to any one of claims 55 to 59, adapted for use in a transdermal delivery formulation.

62. A composition according to claim 61, adapted for use as a transdermal patch.

63. A method of treating a condition caused by disturbance of neuronal 5-HT, while avoiding the concomitant liability of adverse effects which comprises administering to a human in need of such therapy a composition according to any °"•one of claims 55 to 62 in an amount of about 2.0 mg to about 8.0 mg.

64. A method according to claim 63, wherein said composition is administered from one to four times a day.

A method according to claim 64, wherein said composition is administered twice a day.

66. A method according to claim 65, wherein said composition is administered once a day.

67. A method of treating cognitive disorders while avoiding the concomitant liability of adverse effects, which comprises administering to a human in need of such therapy an amount sufficient to alleviate said condition but insufficient to cause said adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer. 34

68. A method according to claim 67, wherein the cognitive disorder is selected from the group consisting of dimentia and age-associated memory impairment.

69. A method according to either claim 67 or 68, wherein ondansetron hydrochloride is administered.

The method according to any one of claims 67 to 69, wherein the ondansetron or pharmaceutically acceptable salt thereof, substantially free of its stereoisomer is administered together with a pharmaceutically acceptable carrier.

71. A method according to any one of claims 67 to 70, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron.

72. A method according to claim 71, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

73. A method according to any one of claims 67 to 72, wherein ondansetron is administered by intravenous infusion, transdermal delivery, orally as a tablet or a capsule.

74. A method according to any one of claims 67 to 73, wherein the amount administered is about 0.001 mg to about 35.0 mg.

A method according to claim 74, wherein the amount administered by intravenous infusion is about 0.001 mg to about 35.0 mg.

76. A method according to claim 74, wherein the amount administered orally is about 0.001 mg to about 35.0 mg.

77. A method according to claim 76, wherein the amount administered orally is about 0.001 mg to about 20.0 mg.

78. A method according to claim 77 wherein the amount administered orally is about 0.001 mg to about 10.0 mg.

79. A composition for treating cognitive disorders, which comprises an amount sufficient to alleviate said condition, but insufficient to cause adverse effects, of ondansetron, or a pharmaceutically acceptable salt thereof, substantially free of its stereoisomer and a pharmaceutically acceptable carrier.

80. A composition according to claim 79 which comprises ondansetron hydrochloride.

81. A composition according to either claim 79 to 80 wherein the amount of ondansetron or pharmaceutically acceptable salt is at least approximately 90% by weight of total ondansetron.

82. A composition according to any one of claims 79 to 81 wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

83. A composition according to any one of claims 79 to 82, adapted for oral administration.

84. A composition according to any one of claims 79 to 82, adapted for intravenous delivery.

85. A composition according to any one of claims 79 to 82, adapted for use in a transdermal delivery formulation. 36

86. A composition according to claim 85, adapted for use as a transdermal patch.

87. A method of eliciting an antiemetic effect while avoiding the concomitant liability of adverse effects which comprises administering to a human in need of antiemetic therapy a composition according to any one of claims 79 to 86 in an amount of about 0.001 mg to about 10.0 mg.

88. A method according to claim 88, wherein said composition is administered from one to four times a day.

89. A method according to claim 86, wherein said composition is administered twice a day. 15

90. A method according to claim 89, wherein said composition is administered once a day.

91. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a human in need of antiemetic :therapy. o°

92. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a human in need of antiemetic therapy, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron.

93. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a human in need of antiemetic therapy, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

94. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of behavioural disorders.

The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a behavioural disorders, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron.

96. The use of an amount of ondansetron substantially free of its 15 stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a behavioural disorders, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron. 20

97. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a condition caused by disturbance of neuronal 5-HT function.

98. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a condition caused by disturbance of neuronal 5-HT function, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron. E 38

99. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment of a condition caused by disturbance of neuronal 5-HT function, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron.

100. The use of an amount of ondansetron substantially free of its 10 stereoisomer or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment cognitive disorders.

101. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the 15 manufacture of a medicament for the treatment of cognitive disorders, wherein °the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 90% by weight of total ondansetron. 0

102. The use of an amount of ondansetron substantially free of its stereoisomer or a pharmaceutically acceptable salt thereof for the 16 manufacture of a medicament for the treatment of cognitive disorders, wherein the amount of ondansetron or pharmaceutically acceptable salt thereof is at least 99% by weight of total ondansetron. Dated: 25 June 1999 PHILLIPS ORMONDE FITZPATRICK Attorneys for: SEPRACOR, INC. O^?i^ktJ4