IE83649B1 - Use of a 1-(2-naphthylethyl)-4-(3-trifluoromethylphenyl)-1,2,3,6- tetra-hydropyridine for the manufacture of a medicament for the treatment of cerebral and neuronal diseases - Google Patents

Description

USE OF A l-(2-NAPHTHYLETHYL)(3-TRIFLUOROMETHYLPHENYL)- 1,2,3,6-TETRAHYDROPYRIDINE FOR THE MANUFACTURE OF A MEDI- CAMENT FOR THE TREATMENT OF CEREBRAL AND NEURONAL DISEASES The present invention concerns the use of a l-(2-naphthyl— ethyl)(3—trifluoromethylphenyl)-l,2,3,6—tetrahydropyri- dine of the following formula N-cH2-cH2 (I) CF3 or of a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the treatment and prophy- laxis of cerebral and neuronal diseases.

More particularly, the present invention concerns the use of a compound of formula (I) or of a pharmaceutically accep table salt thereof for the manufacture of medicaments sui- table for the treatment of diseases associated with neu- ronal degeneration.

The above formula (I) includes l-[2—(l-naphthyl)ethyl]- and l—[2-(2—naphthyl)ethyl](3-trifluoromethylphenyl)-1,2,3, 6-tetrahydropyridines; however, particularly preferred com- pounds for use in the practice of the present invention are l-[2-(2—naphthyl)ethyl](3-trifluoromethylphenyl)-1,2,3, 6-tetrahydropyridine and pharmaceutically acceptable salts thereof.

The compounds of formula (I), as free bases or acid addi- tion salts thereof, as well as their preparation,have been described in EP—A-101381.

The nature of the salt is not critical provided it is phar- maceutically acceptable and acids which may be employed to form such salts are of course well known to those skilled in the art.

Examples of acids which may be employed to form pharmaceuti cally acceptable acid addition salts include such inorganic acids as hydrochloric acid, hydrobromic acid, phosphoric acid, and sulphuric acid and such organic acids as acetic acid, formic acid, propionic acid, benzoic acid, maleic acid, succinic acid, tartaric acid, fumaric acid, citric acid, glyoxylic acid, aspartic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluene sul- fonic acid and the like acids.

In the above European patent application, the compounds are described as anorexigenic agents.

It has now unexpectedly been found that the compounds of formula (I) do exert neurotrophic effects in the nervous system, similar to those of NGF (Nerve Growth Factor) and restore functioning of the nerve cells which are damaged or present anomalies in their physiological role.

Said neurotrophic effects have been demonstrated at first by means of a neuritogenesis test in vitro.

In vitro pharmacological evaluation This test has been carried out on isolated nerve cells which are obtained from dissections of the septal region of rat embryos by conventional procedures which afford enriched neuronal suspensions (from 95 to 98%) (S.E. Bot- tenstein "Growth and differenciation of neural cells in defined media" in Cell Culture in the Neuroscience, p.3-43, l985,Ed. S.E. Bottenstein, G. Sato).

More particularly, the septal region of l7-day-old rat em- bryos has been removed by means of a dissection microscope while keeping said brain tissue at 4°C in the following medium DME/F-12 containing (v/v) % glucose l % amphotericin B 0.5 % gentamycin The cells are dissociated by treatment with trypsin.EDTA at 37°C for 20 minutes, followed by two centrifugations and washing with PBS. Dissociation is then completed by resu- spending the cells in Hanks’ solution and gently pipetting the cell suspension to break up the clumps. This step is followed by three centrifugations and the obtained pellet in then resuspended in a serum—supplemented medium: DME/F-12 containing (v/v) foetal calf serum horse serum o\° o\° o\° glutamine O.l % glutamine l % amphotericin B 0.5 % gentamycin Neurons are plated on to 96 well plates (5 X 104 viable cells per well).

Each well is treated with poly-L-Lysine (lO ug/ml) in order to form a matrix which is necessary to neuronal adhesion, survival and differentiation. Aliquots free medium containing either suitably (130 ul) of serum- selected doses of the test compounds of formula (I) or the corresponding concentrations of the solvent employed (dimethylsulfoxide) are distributed in the wells. After depositing the neuronal cells in the wells, the plates are maintained in the oven at 37°C and 5% CO2 atmosphere for 18 hours.

After glutaraldehyde/paraformaldehyde fixation, the cells in the cultures are counted as follows: - for a predetermined microscopic field in each well, the total number of cells is counted as well as the number of cells having at least one neurite longer than twice the cell diameter, (neurite=outgrowth) — five fields for each well are counted and for each dose of test compound two wells are incubated, thus obtaining ten data for each dose, — the results are expressed as percentage of cells with neu rites relative to total surviving neurons. Each group is compared to its control by means of non-parametric Kru- shall-Wallis analysis.

The results obtained with 1-[2-(2-naphthyl)ethyl](3—tri— fluoromethylphenyl)-1,2,3,6-tetrahydropyridine hydrochlori- de (Compound A) are summarised in following Table I TABLE I I Compound - dose percentage of cells with neuritesI I F I I I Compound A - 2.4 nM I 44.8 r 3.45 I I Control Inmso 1o‘5) I 30.2 : l.68 I I I I I Compound A - 24 nM I 39.2 r 2.39 I I Control (nmso 1o‘5) I 29.4 i 1.64 I I I I I Compound A — 240 nM I 44.1 t 2.02 I I Control (DMSO 1o'4) | 34.3 t 1.82 I NGF in the same test, gave the following results: I | percentage of cells with neuritesj I It ‘I NGF - l.6 nM 51.7 t 1.61 I I I | Control I 40.6 f 2.08 | I I I L 1 I The mechanism through which Compound A elicits said neuro- trophic effects has not been cleared up. Anyway it may be excluded that a serotoninergic effect is involved because Compound A has no affinity for serotonine receptors others than 5—HTlA (i.e. 5—HTlB; 5—HTlc; 5-HTlD; 5-HT2; 5-HT3)and compounds known as 5-HTlA agonists or partial agonists, in- cluding buspirone, ipsapirone, and 8-hydroxy(di-n-propyl amino)tetralin (8OH-DPAT) showed to be completely inactives in the above test.

Compound A also is very active (at concentrations ranging from 250 uM to 2.5 uM) in affording survival of neuronal cells in a very poor medium free from growth factors.

In vivo pharmacological evaluation To confirm the significance of the above in vitro positive results, a new experimental model has been set up which al- lows the in vivo assessment of the neurotrophic/neuropro— tectant activity of the compounds of formula (I) in neuro- nal degenerative processes.

An experimental model for this type of evaluation has recen tly been proposed by Y. Nakagawa et al (Brain Research, l987, ggg, 57-64).

In the study conducted by these Authors, the resemblance between the neurochemical and Behavioural modifications caused by infusion of a neurotoxicant, in particular colchi cine, in the hippocampus and those observed in patients affected by Alzheimer’s disease has been clearly pointed out. On the basis of the results published by Y. Nakagawa et al. and bearing in mind the crucial role played by the hippocampus in memory and learning, it has been attempted to set up an experimental model for the Alzheimer's disea- se of improved feasibility and even closer to the physio- pathologies documented in patients with Alzheimer's disea- se.

The experimental model which is herein provided complies with these requirements: good feasibility and irreversible lesions highly specific for the septohippocampal choline; gic system.

In particular, lesions of the septal neurons have been caused by local injection of vincristine known to be a tubuline polymerisation inhibitor. with respect to other similar compounds (colchicine and vinblastine) and different injection sites (intraventricu— lar and intrahippocampal) which have been tested, optimum results, both in terms of specific blockade of septohippo- campal cholinergic transmission and irreversible lesions, have been obtained.

Operative procedures The animals (male Sprague-Dawley rats weighing about 250 g) are anesthetised with pentobarbital (10 mg/kg i.p.) and placed in a stereotaxic apparatus.

The injection in the medial septum is made at the following coordinates which are calculated according to the atlas of Paxinos and Watson: A. 8.9 L. O H. 6.4 wherein point 0 corresponds to lambda.

Vincristine is dissolved in artificial cephalorachidian liquid (ACSF) having the following composition Nacl 150 mm CaCl2 1.8 mM MgSO4 l.2 mM KZHPO4 2 mM glucose lO mM pH 7.4 at a concentration of 0.6 umole of vincristine per ml. lul of this solution (0.6 nmole of vincristine) is locally injected in the medial septum over 1 minute.

Assessment of the lesions - Evaluation of morphological changes (histoenzymatic AChE determination). ‘ The animals are perfused with a fixating mixture (glutaral- dehyde/paraformaldehyde) via the aorta, with a perfusion flow of 25 ml/min for 5 minutes. Brains are removed, fixa- tion being continued for 1 hour, then washed and cryopro- tected with 20 % sucrose in phosphate buffer. Brains are there cut on a cryostat and the cryostat sections (30 um thick) of the septum and the hippocampus are mounted on me- tal slides which are incubated for about 15 hours in the following medium: ' . distilled water 925 ml 200 ml of a stock solution CUSO4 781 mg glycine 750 mg sodium acetate 2.89 g to which acetylcholine iodide ethopropazine mg and mg are added just before use.

The reaction is then detected by means of 2 % ammonium sul- fide and evidenced by 0.25 % AgNO3.

The presence of acetylcholinesterase (generally associated with cholinergic synapses) is indicated as a dark precipi- tate.

Biochemical observations (ChAT) ChAT activity is determined by the method described by Fon- num (J.Neurochem. gg, l975, 407-409). Tissue samples are homogenised at 4°C. Each sample is brought to a concentra- tion of 1 mg of protein per ml. Aliquots of the obtained homogenates (10 ul) are incubated for 7'30" at 37°C, in the presence of choline (1.5 mM), acetylCoA (70 uM),l4C— acetylCoA (30 uM) and physostigmine (0.15 mM).

The reaction is stopped by lowering the temperature by means of an ice—bath and adding phosphate buffer (5 ml).

After addition of tetraphenylboron/acetone (2 ml) and of a scintillating agent (5 ml), 14C-acetylcholine is counted in a scintillation spectrometer. Each sample is tested in tri- plicate.

Each time the result is compared with that obtained with the corresponding control by the Student test.

Behavioural studies Groups of animals kept with an inverse light-dark cycle have been employed specifically for these studies. The rats used in these tests are Winstar rats lesioned as described above.

Social memory test whereas when there is a memory impairment the T2/Tl ratio is El.

T-maze learning test This test has been carfied out according to the methodology described by P. Soubrié et al., in J. Pharmacol. (Paris), l977,8,3,393-403 for the Y-maze test.

Holeboard test (S.E. File et al., Pharmacol. Biochem. Behav., 1985, g; 941-44).

Assessment of the lesions Intraseptal vincristine administration affords a rapid and significant decrease (from 60 to 70 % within one week after the injection) of the cholinergic'markers of the hippocam- pus (choline acetyltransferase (ChAT) and acetylcholine esterase (AChE)), as well as a degeneration of the medial septum neurons which reaches its maximum two weeks after the injection, and which is associated with a reduction of the cholinergic markers. Said degeneration seems to be ir- reversible as it is still present three months after vincri stine injection and involves functional disorders.

Among those functional alterations which result from vincrg stine administration,the major finding is a consistent and irreversible memory impairment (social memory test).

Parallel assays have brought up i.a. a reduction of the explorative capabilities (T-maze learning test and hole- board test).

Treatment schedules The effects of administering Compound A to the animals le- sioned as above have been compared with those obtained by administering NGF.

Compound A is administered orally, 2 to 3 hours after vin- cristine injection, as a 1% carboxymethylcellulose suspen- sion, 10 ml of suspension per kg of body weight. The con- trols receive the vehicle only. The treatment is chronic, once a day for ll days. Compound A is administered at three different doses: 2.5 mg/kg, 5 mg/kg, and 10 mg/kg to groups _ lo - of 8 animals each, and the animals are sacrificed 24 hours after the end of the treatment.

On the contrary NGF is administered by intraventricular in- fusion, dissolved in artificial cerebrospinal fluid (ACSF) containing 0.01 % rat albumin and gentamycin (1 ml/15 ml) according to the method described by W. Fisher et al., in Nature, 1987, 329 (6134),65—8. NGF concentration in the so lution is calculated in view of the selected diffusion flow rate (0.44 : 0.02 ul/h) so as to provide the animals (7 rats) with an overall amount of 0.105 ug, 1.05 ug, or .5 ug of NGF over two weeks of infusion. In the controls, NGF is replaced by a protein of similar molecular weight (about 130.000) which has no neurotrophic activity: cyto- chrome C. Two weeks after the lesions have been placed and the treatment has begun, the animals are sacrificed. One group of sacrificed animals is perfused for histoenzymatic determination of AChE, the other animals are on the other hand employed for the assay of ChAT activity in both hippo- campus and septum.

Results Morphological observations In the lesioned, untreated, animals no dark precipitate is seen while the hippocampal buddings observed in the ani- mals treated with 5 mg/kg of Compound A are quite similar to those seen in These results are analogous to those obtained in the NGF-treated animals. normal animals.

Biochemical evaluation The lesions provoke a marked decrease of ChAT activity in the hippocampus whose extent is reduced in a dose-dependent manner by Compound A, up to a complete recovery with the dose of 10 mg/kg. Analogous results are obtained in the NGF perfused animals. _ ll _ Mose particularly the obtained results are summariaed in the following table II Table II I I IChAT activity (pmols/mg/mn) 1 I I *1 Inon-lesioned normal animals I 277 i 13 I Ilesioned controls I ll5 i 18 I INGF 0.105 uq/rat/2 weeks I 168 t 27 I INGF l.05 ug/rat/2 weeks I 336 i 28 I INGF 10.5 ug/rat/2 weeks I 293 : 10 I I I fl‘ Inon-lesioned normal animals I 242 t 19 I Ilesioned controls I 97 2 l8 I Icompounds A 2.5 mg/kg/day I 164 t 42 I Icompounds A 5 mg/kg/day I 204 i 24 I Icompounds A 10 mg/kg/day I 242 t 27 I I In the septum, the lesions afford reduction of ChAT acti- vity which is restored, in a dose-dependent manner, by the administration of Compound A. the results are not In the NGF-treated animals significative probably because addition to the septal necrosis produced by the vincristine injection, an additional necrosis associated with the implantation of a cannula in a ventricle near the septum develops.

Behavioural observations Social memory test The vincristine lesioned animals show alterations in social memory which seem to be irreversible still present 50 days after vincristine injection). (said alterations are -12..

Compound A has been tested at the dose of 10 mg/kg per os in comparison with NGF at the dose of lO.5 ug and the test has been performed on day '7 from placement of the lesions.

In both cases a very important protecting effect has been elicited with a T2/Tl ratio of between 0.6 and 0.7.

T-maze test The results obtained in the lesioned, untreated, animals show an alteration in the exploratory activity which is however restored to the normal level by administration of 10 mg/kg of Compound A.

This test has been carried out in blind, 7 days after the end of the treatment.

Holeboard test In the controls, most of the animals (6 rats) completely lost their exploratory capacity, while only two rats showed an exploratory hyperactivity. Treatment with Compound A at the dose of 10 mg/kg leads to a normalisation of the explo- rative behaviour compared with the average results obtained with unlesioned animals.

Said test too has been carried out in blind, ll days after the end of the treatment.

In the light of the results obtained in the above model,the use of the compounds of formula (I) as well as of their pharmaceutically acceptable salts in the treatment and/or prevention of diseases involving neuronal degeneration can be envisaged. More particularly the compounds of formula.

(I) as well as their pharmaceutically acceptable salts can be employed mainly in the following indications: memory im- pairment, vascular dementia, post-encephalitic disorders, post-apoplectic disorders, post-traumatic syndrome caused by injury to the head, degenerative modifications associated with cerebral anoxia, Alzheimer's disease, senile dementia, sub-cortical dementia, such as Huntington's chorea and Parkinson's disease, AIDS dementia, neuropathies caused by lesions or degeneration of sympa- thetic or sensory nerves and cerebral diseases such as cerebral oedema and spinocerebellar degenerations.

The compounds of formula (I) or their pharmaceutically ac- ceptable acid addition salts may advantageously be admini- stered orally, parenterally, sublingually or transdermally.

The amount of active principle to be administered in the treatment of cerebral and neuronal diseases according to the method of the present invention will vary, as usually depending on the nature and conditions of the disease to be treated as well as on the weight of the patients.

Generally speaking, preferred unit dosage forms will con- tain from 2 to 300 mg, preferably from 5 to 150 mg, com- prised by way of example between S and 50 mg, e.g. 5,lO,20, ,40, and 50 mg, of active principle. Said unit doses are generally administered one or more times a day, e.g. 2,3,4, or 5 times a day, preferably from 1 to 3 times a day, the overall daily dosage in humans being from 2 to 900 mg, ty- pically from 3 to 500 mg, more advantageously from 10 to 300 mg. M For a therapeutic or preventive treatment according to the present invention, the compounds of formula (I) and their pharmaceutically acceptable acid addition salts are prefe- rably formulated in pharmaceutical compositions.

The pharmaceutical compositions of the present invention contain an amount of at least one compound selected from the compounds of formula (I) and their pharmaceutically acceptable addition salts which is effective for the treat- ment or the prevention of cerebral and neuronal diseases, in admixture with a pharmaceutically inert carrier.

As for the oral or sublingual administration, in particular tablets, optionally sugar-coated, capsules, optionally con- taining a slow-release formulation, drops or liposomes may _ 14 _ be used. As for the intramuscular intravenous, subcutaneous, or administration, sterile or sterilisable solutions are employed, while conventional patches for transdermal administration can be utilised.

The pharmaceutical compositions according to the present invention can be prepared by conventional techniques such as those EP—lOl38l or in th described in Pharmaceutical Sciences, 18 Remington's Ed, mack Publishing Company.

The active principle may be incorporated to excipients usually employed in said pharmaceutical compositions, such as talc, arabic gum, lactose, starch, magnesium stearate, aqueous or non aqueous vehicles, animal or vegetable fats, paraffins, glycols, wetting, dispersing, emulsifying and preservative agents, etc.

The pharmaceutical compositions according to the invention may advantageously contain a compound of formula (I) or a pharmaceutically acceptable salt thereof in association with one or more other medicaments, known or actually em- ployed for the same indications. therapeutic or prophylactic

Claims (10)

1.Claims Use of at least one compound of formula (I) / N-CH;-CH U) or of a pharmaceutically acceptable acid addition salt thereof for the preparation of CF3 a medicament intended for the treatment and/or the prophylaxis of cerebral and neuronal diseases.

2. Use according to claim 1 for the preparation of a medicament intended for the treatment and/or the prophylaxis of diseases which involve neuronal degeneration.

3. Use according to claim 2 for the preparation of a medicament intended for the treatment and/or the prophylaxis of memory disorders, vascular dementia, post— encephalitic disorders, post-apoplectic disorders, post— traumatic syndrome due to skull trauma, disorders deriving from cerebral anoxia, Alzheimer's disease, senile dementia, sub-cortical dementia such as Huntington's chorea and Parkinson's disease, dementia provoked by AIDS, neuro-pathies deriving from morbidity or damage to the sympathetic or sensory nerves, cerebral oedema or spinocerebellar degenerations.

4. Use according to claim 3 for the preparation of a medicament intended for the treatment of vascular dementia, senile dementia or Alzheimer's disease.

5. Use according to any one of claims 1 to 4 wherein the compound of formula (I) is selected from 1-[2-(2-naphthyl)ethy|](3- trifluoromethylphenyl)-1,2,3,6- tetrahydropyridine and the pharmaceutically acceptable acid addition salts thereof.

6. Use according to any one of claims 1 to 5 wherein the medicament is a pharmaceutical composition in unit dosage form.

7. Use according to claim 6 wherein the unit dosage form comprises from 2 to 300 mg of active principle.

8. Use according to claim 7 wherein the unit dosage form comprises from 5 to 150 mg of active principle.

9. Use according to claim 8 wherein the unit dosage form comprises from 5 to 50 mg of active principle.

10. Use according to claim 1, substantially as herein described. MACLACHLAN & DONALDSON, App|icant’s Agents, 47 Merrion Square, DUBLIN 2.