WO2005067930A2

WO2005067930A2 - Serotonin receptor antagonists for the treatment of neurological disease

Info

Publication number: WO2005067930A2
Application number: PCT/GB2005/000118
Authority: WO
Inventors: Paul Goldsmith; Frances Margaret Richards; Derek Thomas Edward Jones; Ann Gail Hayes
Original assignee: Daniolabs Ltd
Current assignee: Daniolabs Ltd
Priority date: 2004-01-14
Filing date: 2005-01-14
Publication date: 2005-07-28
Anticipated expiration: 2006-07-14
Also published as: WO2005067931A2; GB0400802D0; WO2005067931A3; WO2005067930A3

Abstract

Treatment of diseases and disorders related to altered neuronal excitability, especially migraine prophylaxis, mood stabilisation and convulsions, in particular the treatment of convulsions due to epilepsy, also treatment of depression or psychomotor retardation in subjects prone to seizures. Serotonin receptor antagonists are employed, especially antagonists that are selective for 5-HT2 receptors, and ergolines, ergoline derivatives and analogues, in particular LY-53857.

Description

SEROTONIN RECEPTOR ANTAGONISTS FOR THE TREATMENT OF NEUROLOGICAL DISEASE

This invention relates to the treatment of diseases and disorders related to altered neuronal excitability, especially migraine prophylaxis, mood stabilisation and convulsions, in particular the treatment of convulsions due to epilepsy, also treatment of depression or psychomotor retardation in subjects prone to seizures.

Epilepsy is a serious neurological condition, associated with seizures, that affects hundreds of thousands of people worldwide. Clinically a seizure results from synchronous electrical discharge from a collection of neurons in the brain. The resulting nerve cell activity is manifested by symptoms such as uncontrolled movements.

Although epileptic seizures are rarely fatal, large numbers of patients require medication to avoid the disruptive, potentially dangerous, consequences of seizures. In many cases, medication is required for extended periods of time, and in some case patients must continue to take prescription drugs for life. A variety of drugs are available for management of epilepsy, including older anticonvulsants such as valproate, phenytoin, carbamazepine, and newer agents such as gabapentin, lamotrigine, tiagabine and felbamate . Some patients do not respond well to the currently available treatments, and the drugs currently used for management of epilepsy have side effects associated with prolonged usage. This is a major problem given that for many patients epilepsy is a life long disorder. Moreover, the taking of medication during childhood or during childbearing age has major teratogenic and developmental implications. There is therefore a need to identify and develop novel treatments for this disorder .

Brief Description of the Figures

Figure 1 shows the combined results of at least 3 independent assays for each compound, together with results for negative controls (PTZ alone) and positive controls (carbamazepine and diazepam) in the same assays.

Figure 2 shows various compounds of use in embodiments of the present invention, many of which are shown as maleate or other salts. It is apparent, of course, that other salts, especially acid salts, including organic salts, are encompassed by the present invention and useful in embodiments thereof .

It was found that the test compounds shown were anticonvulsant .

The present invention is based on the surprising finding that certain compounds can be used in the treatment of convulsions. The identification of the useful compounds has been achieved using a specific model of epilepsy using zebrafish as the disease model.

According to a first aspect of the invention, a compound which is a serotonin receptor antagonist is used in treatment of a disease or disorder of neuronal excitability, such as epilepsy.

Various aspects and embodiments of the present invention include : Use of a compound selected from serotonin receptor antagonists in the manufacture of a medicament for the treatment of a neurological disease.

Use where the serotonin receptor antagonists are ergolines .

Use where the serotonin receptor antagonists are benzhydryl piperazine derivatives.

Use where the serotonin receptor antagonists are phenyl piperazine derivatives.

Use where the serotonin receptor antagonists are phenyl piperidinyl methanone derivatives .

Use where the, serotonin receptor antagonists are benzhydrylidine piperidine derivatives .

Use where the compound is selected from any of those specifically disclosed herein, preferably shown in Figure 2, preferably LY-53857, and pharmaceutically acceptable salts thereof. Preferred pharmaceutically acceptable salts include acid salts, especially organic acid salts, e.g. maleate. LY- 53857 or an analogue thereof.

Use wherein the compound is a pharmaceutically acceptable salt of, or a prodrug form that is metabolised to, one of the compounds as defined.

Use wherein the neurological disease is selected from the group consisting of epilepsy, chronic, recurrent and paroxysmal headache syndromes, including migraine, cluster headache and chronic daily headache variants, chronic pain states, trigeminal neuralgia, bipolar disease, unipolar disease, neuropathic pain, paroxysmal movement disorders.

A method for the treatment of a neurological disease, comprising administering to a patient suffering a neurological disease a compound selected ^' from the class of compounds defined in any of the above.

A method wherein the neurological ' disease is selected from those defined above.

Use or a method wherein the subject is a non-human animal.

Use or a method wherein the subject is human.

In preferred embodiments, the compound is selected from serotonin receptor antagonists that are selective for 5-HT2 receptors .

The compound may be a 5-HT2a serotonin receptor antagonist.

Ergolines, ergoline derivatives and analogues represent a preferred class of compound of use in embodiments of the present invention, among which are LY-53857.

LY53857 is a non-specific 5HT2 antagonist.

5HT2a receptors are expressed in CNS and PNS tissues; 5HT2b receptors are principally in the periphery and only sparsely located in CNS; 5HT2c receptors are primarily in the CNS. As 5HT2c agonists rather than antagonists are anticonvulsant, this receptor seems unlikely to be responsible for the effect of LY-53857. 5HT2b receptors are also unlikely candidates given that they are mainly peripheral, and that 5HT2b agonists have no effect in seizure models. So the most likely scenario is that the effect of LY-53857 is mediated through 5HT2a receptors or some other target.

A list of the various classes of drugs useful in the present invention, together with specific examples of each compound class is shown in Table 1:

Table 1

The compounds of the invention may be prepared in racemic form, or prepared in individual enantiomeric form by specific synthesis or resolution as will be appreciated in the art. The compounds may, for example, be resolved into their enantiomers by standard techniques, such as the formation of diastereomeric pairs by salt formation with an optically active acid followed by fractional crystallisation and regeneration of the free base. Alternatively, the enantiomers of the novel compounds may be separated by HPLC using a chiral column .

The compounds of the invention may be in a protected amino form. The term "protected amino" as used herein refers to an amino group which is protected in a manner familiar to those skilled in the art. For example, an amino group can be protected by a benzyloxycarbonyl, tert-butoxycarbonyl, acetyl or like group, or in the form of a phthalimido or like group.

Some compounds of the formula may exist in the form of solvates, for example hydrates, which also fall within the scope of the present invention.

The compounds of the invention may exist and may be employed in a prodrug form. Suitable groups will be apparent to the skilled person. Compounds of the invention may be in the form of pharmaceutically acceptable salts, for example, addition salts of inorganic or organic acids. Such inorganic acid addition salts include, for example, salts of hydrobromic acid, hydrochloric acid, nitric acid, phosphoric acid and sulphuric acid. Organic acid addition salts include, for example, salts of acetic acid, benzenesulphonic acid, benzoic acid, camphorsulphonic acid, citric acid, 2- (4-chlorophenoxy) -2- methylpropionic acid, 1, 2-ethanedisulphonic acid, ethanesulphonic acid, ethylenediaminetetraacetic acid (EDTA) , fumaric acid, glucoheptonic acid, gluconic acid, glutamic acid, N-glycolylarsanilic acid, 4-hexylresorcinol, hippuric acid, 2- (4-hydroxybenzoyl) benzoic acid, l-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 2-hydroxyethanesulphonic acid, lactobionic acid, n-dodecyl sulphate, maleic acid, malic acid, andelic acid, methanesulphonic acid, methyl sulphate, mucic acid, 2-naphthalenesulphonic acid, pamoic acid, pantothenic acid, phosphanilic acid (( 4-aminophenyl) phosphonic acid) , picric acid, salicyclic acid, stearic acid, succinic acid, tannic acid, tartaric acid, terephthalic acid, p- toluenesulphonic acid, 10-undecenoic acid and the like. Salts may also be formed with inorganic bases. Such inorganic base salts include, for example, salts of aluminium, bismuth, calcium, lithium, magnesium, potassium, sodium, zinc and the like.

It will be appreciated that such salts, provided that they are pharmaceutically acceptable, may be used in therapy. Such salts may be prepared by reacting the compound with a suitable acid or base in a conventional manner.

The compounds of the invention may be used in the treatment of epilepsy, but not limited thereto. They may also be useful in conditions known to respond to anticonvulsant therapy, including chronic pain states, migraine, chronic headaches and mood disorders. The invention is applicable to any disease or disorder of altered neuronal excitability, including epilepsy, migraine prophylaxis and mood stabilisation. It is applicable to treatment of depression and psychomotor retardation in a subject prone to seizures.

In therapeutic use, the active compound may be administered orally, rectally, parenterally, by inhalation (pulmonary delivery) , topically, ocularly, nasally, or to the buccal cavity. Oral administration is preferred. Thus, the therapeutic compositions of the present invention may take the form of any of the known pharmaceutical compositions for such methods of administration. The compositions may be formulated in a manner known to those skilled in the art so as to give a controlled release, for example rapid release or sustained release, of the compounds of the present invention.

Pharmaceutically acceptable carriers suitable for use in such compositions are well known in the art. The compositions of the invention may contain 0.1-99% by weight of active compound. The compositions of the invention are generally prepared in unit dosage form. Preferably, a unit dose comprises the active ingredient in an amount of 1-500 mg. The excipients used in the preparation of these compositions are the excipients known in the art.

Appropriate dosage levels may be determined by any suitable method known to one skilled in the art. It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the disease undergoing treatment .

Compositions for oral administration are preferred compositions of the invention and there are known pharmaceutical forms for such administration, for example tablets, capsules, granules, syrups and aqueous or oily suspensions. The pharmaceutical composition containing the active ingredient may be in a form suitable for oral use, for example, as tablets, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups or elixirs. Compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions, and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavouring agents, colouring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations . Tablets contain the active ingredient in admixture with non- toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example corn starch or alginic acid; binding agents, for example starch gelatin, acacia, microcrystalline cellulose or polyvinyl pyrrolidone; and . lubricating agents, for example magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. For example, a time delay material such as glyceryl monostearate or glyceryl distearate may be employed.

Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin or olive oil.

Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients are suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinyl pyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents may be a naturally occurring phosphatide, for example lecithin, or condensation products of an alkylene oxide with fatty acids, for example polyoxyethylene stearate, or condensation products of ethylene oxide with long-chain aliphatic alcohols, for example heptadecaethyleneoxycetanol, or condensation products of ethylene oxide with partial esters derived from fatty acids, for example polyoxyethylene sorbitan monooleate. The aqueous suspensions may also contain one or more preservatives, for example ethyl, or n-propyl, p- hydroxybenzoate, one or more colouring agents, one or more flavouring agents, and one or more sweetening agents, such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents, such as those set forth above, and flavouring agents may be added to provide a palatable oral preparation. These compositions may be preserved by the addition of an antioxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable sweetening, flavouring and colouring agents may also be present.

The pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions. The oily phase may be a vegetable oil, for example olive oil or arachis oil, or a mineral oil, for example liquid paraffin, or mixtures of these. Suitable emulsifying agents may be naturally occurring gums, for example gum acacia or gum tragacanth, naturally occurring phosphatides, for example soya bean, lecithin, and esters or partial esters derived from fatty acids and hexitol anhydrides, for example sorbitan monooleate and condensation products of the said partial esters with ethylene oxide, for example polyoxyethylene sorbitan monooleate. The emulsions may also contain sweetening and flavouring agents. Syrups and elixirs may be formulated with sweetening agents, for example glycerol, propylene glycol, sorbitol or sucrose. Such formulations may also contain a demulcent, a preservative and flavouring and colouring agents. The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleagenous suspension. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents which have been mentioned above. The sterile injectable preparation may also be in a sterile injectable solution or suspension in a non-toxic parenterally acceptable diluent or solvent, for example as a solution in 1, 3-butanediol . Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono- or diglycerides . In addition, fatty acids such as oleic acid, find use in the preparation of injectables.

The following Examples illustrate the invention.

EXPERIMENTATION

Example 1

Screening protocol

Zebrafish in which epilepsy is induced as follows were employed in screens :

1. Zebrafish larvae in 96 well plates are immersed in embryo medium with or without the test compound at a non-toxic concentration, for 24 hours from 6 days post fertilization (6dpf) .

2. The fish are then incubated in embryo medium containing the proconvulsant pentylene tetrazole (PTZ) at 15mM, in the presence or absence of the test compound, for a period of 8 to 16 hours. During this time the PTZ-treated fish exhibit multiple seizures and then enter status epilepticus which is manifested by loss of responsiveness to a tap on the dish.

3. Fish are then either scored immediately or transferred to fresh embryo medium and allowed to recover for 16 hours before scoring .

4. The extent of response to PTZ is scored for each fish based on: a. Responsiveness to a tap on the dish, by exhibiting movement b. Viability - alive or dead

As an example of the invention, assays were performed in this zebrafish model of epilepsy with various compounds, as shown in Table 2 and Figure 1.

Table 2

Dose response curves were performed for each compound to determine active and toxic doses. The results for at least 3 independent assays for each compound are combined in Table 2. Fish at 6dpf were treated with compound for 22 hours prior to the addition of 15mM PTZ for 6.5 hours, then the fish were allowed to recover in embryo medium for 16 hours prior to scoring the percentage of responsive fish. The mean and standard deviation has been calculated from these figures . responsiveness at optimum dose

Example 2

LY-53,857 was tested in mouse and rat models, as follows.

The standard models incorporated into anticonvulsant screening at the ASP include the maximal electroshock test (MES) , the subcutaneous Metrazol test (scMET) , and evaluations of toxicity (TOX) . The data for each condition are presented as N/F, where N=number of animals protected and F=number of animals tested. For tests of toxicity (TOX) , N=number of animals displaying toxic effects and F=number of animals tested. Codes in the C column refer to comments from the technicians performing the experiment and are defined in the comments section if necessary. Any deaths are noted.

Maximal Electroshock Test (MES)

The MES is a model for generalized tonic-clonic seizures and provides an indication of a compound' s ability to prevent seizure spread when all neuronal circuits in the brain are maximally active. These seizures are highly reproducible and are electrophysiologically consistent with human seizures. For all tests based on MES convulsions, 60Hz of alternating current (50 mA in mice, 150 in rats) is delivered for 2s by corneal electrodes which have been primed with an electrolyte solution containing an anesthetic agent (0.5% tetracaine HCL) . For Test 1, mice are tested at various intervals following doses of 30, 100 and 300 mg/kg of test compound given by i.p. injection of a volume of 0.01 mL/g. In Test 2, rats are tested after a dose of 30 mg/kg (p.o.) in a volume of 0.04 mL/g. Test 3 uses varying doses administered via i.p. injection, again in a volume of 0.04 ml/g. An animal is considered "protected" from MES-induced seizures upon abolition of the hindlimb tonic extensor component of the seizure (Swinyard et al . , 1989, General principles: experimental selection, quantification, and evaluation of anticonvulsants, in Antiepileptic Drugs (R.H.Levy RHM, B. Melrum, J.K. Penry and F.E. Dreifuss ed) pp 85-102, Raven Press, New York.; White et al., 1995a, Ital J Neurol Sci 16:73-7; White et al . , 1995b, General principles: experimental selection, quantification, and evaluation of antiepileptic drugs, in Antiepileptic Drugs (Levy RHM, R.H.; Meldrum, B.S. ed) pp 99-110, Raven Press, New York) .

Subcutaneous Metrazol Seizure Threshold Test (scMET)

Subcutaneous injection of the convulsant Metrazol produces clonic seizures in laboratory animals. The scMET test detects the 'ability of a test compound to raise the seizure threshold of an animal and thus protect it from exhibiting a clonic seizure. Animals are pretreated with various doses of the test compound (in a similar manner to the MES test, although a dose of 50 mg/kg (p.o.) is the standard for Test 2 scMET) . At the previously determined TPE of the test compound, the dose of Metrazol which will induce convulsions in 97% of animals (CD₉ : 85 mg/kg mice) is injected into a loose fold of skin in the midline of the neck. The animals are placed in isolation cages to minimize stress (Swinyard et al . , 1961, J Physiol 132:97-102) and observed for the next 30 minutes for the presence or absence of a seizure. An episode of clonic spasms, approximately 3-5 seconds, of the fore and/or hindlimbs, jaws, or vibrissae is taken as the endpoint. Animals which do not meet this criterion are considered protected.

Acute Toxicity—Minimal Motor Impairment

To assess a compound's undesirable side effects (toxicity), animals are monitored for overt signs of impaired neurological or muscular function. In mice, the rotorod (Dunham and Miya, 1957, J. Amer. Pharm . Ass . Sci . Ed. 46:208-209) procedure is used to disclose minimal muscular or neurological impairment. When a mouse is placed on a rod that rotates at a speed of 6 rpm, the animal can maintain its equilibrium for long periods of time. The animal is considered toxic if it falls off this rotating rod three times during a 1-min period. In rats, minimal motor deficit is indicated by ataxia, which is manifested by an abnormal, uncoordinated gait. Rats used for evaluating toxicity are examined before the test drug is administered, since individual animals may have peculiarities in gait, equilibrium, placing response, etc., which might be attributed erroneously to the test substance. In addition to MMI, animals may exhibit a circular or zigzag gait, abnormal body posture and spread of the legs, tremors, hyperactivity, lack of exploratory behavior, somnolence, stupor, catalepsy, loss of placing response and changes in muscle tone.

Results are shown in Table 3 (Test 1), Table 4 (Test 2) and Table 5 (Test 3) . In these tables the solvent code MC indicates that the compound was suspended in 0.5% methylcellulose (in distilled water) . Under solvent prep, M&P/SB indicates that the compound was ground with a mortar and pestle to make the suspension, followed by a 10 minute incubation in a sonabath (sonicator) . Similarly, in the test results area, at each dose, it is indicated whether the compound was in suspension (SUS) or solution (SOL) .

Table 3 Test 1 Results - Mice I.P. Identification

olvent Code: MC Solvent Prep: M&P.SB nimal Weight: 20.5 to 23.0 g

esponse S BISi :' s v;-' ό;V- ^'όlf - ϊifi ''■^■$ -z 'ft^'β V; b/ ^■IMY ^■z y

Test : Dose¹ ^oπtT ;Dths ff-^'if. o. ^':/;,F;^:: p) ^" .. ^"ά ! Hl'Si ;G: c- ,.H; ^' c. frJ- ;^' C; W! F e ^■NV- C

MES ' 30 SOL 0 /1 0 /1 1 / 1 / / / /

MES 100 SUS ! 2 /3 0 /3 1 / I / / / /

MES 300 SUS ' 1 /1 0 /1 1 / 1 / / / /

CMET 30 SOL ' 0 /1 ; 0 /1 1 / 1 / / / / i

CMET 100 SUS 0 /1 i 0 / 1 I / 1 / / / /

CMET 300 SUS 0 /1 3 0 /1 5 1 / 1 / / / /

TOX 30 SOL 0 /4 0 /2 1 / 1 / / / /

TOX 100 SUS 4 /8 * 0 /4 1 / 1 / / / /

TOX 300 SUS 4 /4 * 211 * 1 / / / / / /

esponse Comments

Table 4 Test 2 Results - Rat P.O. Identification

lolvent Code: MC Solvent Prep: M&P.SB animal Weight: 100 to 125 g

miiiii mm ms mm m lesponse

llilKlipi ts

Table 5 Test 3 Results -Anticonvulsant Identification (Rats I.P.)

olventCode: MC Solvent Prep: M&P.SB inimal Weight: 100 to 130g

A > - ' t > .' ^{J !}" ⁱV^ft ^*• *<*" t- U] ime to Peak Effect Test Dose # 0.25 0.5 1.0 2.0 4.0 6.0 8.0 24 3.0 (mg/kg) Dths N /F C N /F C N / F C N / F C N /F C N / F C N / F C N / F C N / F C MES 30 2 /4 1 /4 1 /4 0 /4 0 14 / / / 1

SCMET 30 / / / / 1 / / 1 /2 / TOX 30 0 14 0 14 0 /4 0 /4 0 14 / / 0 12 /

"3 f ft' ' I* /' 1

Claims

1. Use of a compound which is a serotonin receptor antagonist which is selected from the group consisting of ergolines, ergoline derivatives and analogues, and/or which is a 5-HT2a serotonin receptor antagonist, in the manufacture of a medicament for the treatment in a mammal of a neurological disease or disorder related to altered neuronal excitability.

2. Use according to claim 1 wherein the medicament is for treatment of epilepsy, migraine prophylaxis or mood stabilisation.

3. Use according to claim 2 wherein the medicament is for treatment of epilepsy.

4. Use according to claim 1 wherein the medicament is for treatment of depression or psychomotor retardation in a subject prone to seizures.

5. Use according to any one of claims 1 to 4 wherein the compound is selected from the group consisting of LY53857, Ly215840, 4-hydroxyamesergide, amesergide, propisergide, methysergide, 1-isopropyldihydrolysergic acid, dosergoside, 1- methyllysergic acid butanolamide , sergolexole maleate, ergonovine, ergometrinine, methylergonovine , lysergide, ZK- 112566, and pharmaceutically acceptable salts thereof.

6. Use according to claim 5, wherein the compound is selected from any of those of which the structure is shown in Figure 2, and pharmaceutically acceptable salts .

7. Use according to claim 6 wherein the compound is LY- 53857, or a pharmaceutically acceptable salt.

8. A method of treatment of a neurological disease or disorder related to altered neuronal excitability in a mammal, the method comprising administering a compound which is a serotonin receptor antagonist which is selected from the group consisting of ergolines, ergoline derivatives and analogues and/or is a 5-HT2a serotonin receptor antagonist to the mammal in an amount effective to treat the disorder.

9. A method according to claim 8 wherein the treatment is of a disease or disorder as recited in any one of claims 2 to 4.

10. A method according to claim 8 wherein the compound is as recited in any one of claims 5 to 7.