USE OF 2-(4-METHOXYPHENYL)-PYRAZOLO(4,3-C)QUINOLIN-3-ONE IN THE MANUFACTURE OF A MEDICAMENT FOR ENHANCING COGNITION

Abstract: The present invention provides the use of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for enhancing cognition, particularly in Alzheimer's Disease, a method of enhancing cognition and pharmaceutically acceptable salts such as the hemi camphor sulfonate.

Description: USE OF 2-(4-METHOXYPHENYL)-PYRAZOLO(4,3-C)QUINOLIN-3-ONE IN THE MANUFACTURE OF A MEDICAMENT FOR ENHANCING COGNITION The present invention provides a method of treatment for enhancing 5 cognition (for example in the treatment of dementing illnesses such as Alzheimer's disease), the manufacture of medicaments useful for such treatment, pharmaceutical compositions and compounds. A number of dementing illnesses and cognition deficit states are characterised by poor and often a progressive deterioration in the 10 cognition of the sufferer. It would clearly be desirable to enhance cognition in subjects desirous of such treatments. International Patent Application No. PCT/GB 96/00377 discloses that certain GABAα 5 receptor inverse agonists ("α5 inverse agonists") may be used to enhance cognition without producing convulsions. Also by choosing an s inverse agonist 15 that does not have significant α 1; α 2 , or α 3 agonism it is possible to avoid benzodiazepine receptor activity such as that associated with marked anxiolytic, sedative or anti- depressive effects. US Patent No. 4,312,870 ("the US Patent") disclosed broad groups of 2-aryl-pyrazolo[4,3-c]quinolin-3-(l and 3H)-ones which were said to be 20 useful in the treatment of anxiety and depression. Certain of the compounds disclosed in the US Patent have been tested further, see for example Yokoyama et al, J. Med. Chem., 1982, 25, 337-339 and Bennett, Physiology & Behaviours, 1987, 41, 241-245. The Yokoyama paper disclosed that the compounds of the formula (I): 25 wherein R is (a) hydrogen, (b) chlorine or (c) methoxy have an order of magnitude greater affinity for the benzodiazepine receptors than diazepam with 3a being a potent benzodiazepine antagonist, 3b being diazepam-like and 3c acting as an agonist (diazepam-like) at lower doses and antagonist at higher doses. The latter, more detailed paper by Bennett concludes that compounds lb offers the potential for effective anxiolytic therapy (having been employed clinically) and that compound la could be used for the treatment of benzodiazepine overdose. Compound Ic was shown to be only half as effective as related compounds in producing anti-conflict effects. Subsequently the skilled worker is aware that none of the compounds of formula I proved to be acceptable as marketed medicaments (from which the skilled worker could conclude that the compounds of formula la and lb cause unacceptable side effects or lack of clinical efficacy). Finally, the assignee of the US Patent demonstrated the lack of value attributed to the compounds by them by not paying the patent renewal fees on the UK equivalent of the US Patent by 1994. Clearly, in view of what the skilled worker knows about the compounds of the US Patent, the skilled worker would not investigate their behaviours further. However, most surprisingly, it has been found that 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one and its pharmaceutically acceptable salts are useful for the treatment of conditions requiring the enhancement of cognition such as those indicated hereinbefore. Accordingly, the present invention provides a method of treatment of a condition requiring the enhancement of cognition in a subject which comprises administering to the subject in need thereof a cognition enhancing amount of 2-(4-methoxyphenyl)- pyrazolo[4,3-c]quinolin-3(5H)-one or a pharmaceutically acceptable salt thereof. The method will be applied to a mammal, most aptly to a human, preferably to a human suffering from a dementing illness and most preferably to a human suffering from Alzheimer's disease. It is a great advantage that the method of this invention leads to the enhancement of cognition without being convulsant. Other advantages include not being sedative. In addition, anxiolytic and anti- depressive effects are not prominent. It is believed that 2-(4- methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one and its pharmaceutically acceptable salts are able to achieve this desirable end by virtue of being a GABAA s inverse agonist without possessing major agonist or inverse agonist properties at the GABAAC , α 2 , or α 3 receptors. It is considered more desirable to use a pharmaceutically acceptable salt of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one. Most aptly such a salt is one which is significantly more soluble than the parent quinolinone. Suitable pharmaceutically acceptable salts include acid addition salts with mineral or organic acids such as the salts with hydrochloric, sulphuric, hydrobromic, phosphoric, methane sulfonic, ethane sulfonic, camphor sulfonic, acetic, lactic, citric, tartaric, maleic, benzoic, propionic, succinic, fumaric, gluconic or malic acid. Favoured salts include those of non-volatile acids. Particularly favoured salts include hemi camphor sulfonate (hemi campsylate). The compositions are most aptly adapted for oral administration to humans although parenteral modes of administration are also envisaged, for example by intravenous, intramuscular or subcutaneous administration or topically or rectally. For oral use of the cognition enhancer the selected compound may be administered for example in the form of a tablet or a pharmaceutically acceptable carriers or diluents, optionally with known adjuvants, such as alum, in a pharmaceutical composition, according to standard pharmaceutical practice. The compounds can be administered orally, parenterally, including by intravenous, intramuscular, intraperitoneal or subcutaneous administration, or topically. For oral use the cognition enhancer may be administered, for example, in the form of tablets or capsules, or as an aqueous solution or suspension. In the case of tablets for oral use, carriers which are commonly used include lactose, microcrystalline cellulose, carboxymethyl cellulose and corn starch, and lubricating agents, such as magnesium stearate, are commonly added. For oral administration in capsule form, useful diluents include lactose and dried corn starch. When aqueous suspensions are required for oral use, the active ingredient is combined with emulsifying and suspending agents. If desired, certain sweetening and/or flavouring agents may be added. For intramuscular, intraperitoneal, subcutaneous and intravenous use, sterile solutions of the active ingredient are usually prepared, and the pH of the solutions should be suitably adjusted and buffered. For intravenous use, the total concentration of solutes should be controlled in order to render the preparation isotonic. For topical administration, the cognition enhancer may be formulated as, for example, a suspension, lotion, cream or ointment employing a pharmaceutically acceptable carrier such as, for example, water, mixtures of water and water-miscible solvents such as lower alkanes, vegetable oils, polyalkylene glycols and the like. The pharmaceutical preparation may also contain non-toxic auxiliary substances such as emulsifying, preserving, wetting agents, bodying agents and the like, as for example, polyethylene glycols 200, 300, 400 and 600, carbowaxes 1,000, 1,500, 4,000, 6,000 and 10,000, antibacterial components such as quaternary ammonium compounds, phenylmercuric salts known to have cold sterilizing properties and which are non-injurious in use, thimerosal, methyl and propyl paraben, benzyl alcohol, phenyl ethanol, buffering ingredients such as sodium chloride, sodium borate, sodium acetates, gluconate buffers, and other conventional ingredients such as sorbitan monolaurate, triethanolamine, oleate, polyoxyethylene sorbitan monopalmitylate, dioctyl sodium sulfosuccinate, monothioglycerol, thiosorbitol, ethylenediamine tetraacetic acid, and the like. When a cognition enhancer is used in a human subject, the daily dosage will normally be determined by the prescribing physician with the dosage generally varying according to the age, weight, and response of the individual patient, as well as the severity of the patient's symptoms. However, in most instances, an effective daily dosage will be in the range from about 0.005mg/kg to about lOOmg/kg of body weight, and preferably, of from 0.05mg/kg to about 50mg/kg, such as from about 0.5mg/kg to about 20mg/kg of body weight, administered in single or divided doses. In some cases, however, dosage outside these limits may be used. Generally the daily dose will be administered as in from 1 to 6 times a day, generally 1 to 3 times per day. Generally unit dose forms for oral administration will contain from 1 to 800 mgs, more usually 2.5 to 250 mgs, preferably 5 to 100 mgs, for example 10, 20 or 50 mgs. Preferably the unit dosage form is in the form of a tablet. This invention also provides a method of manufacture of a medicament for the enhancement of cognition, which comprises the use of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one or a pharmaceutically acceptable salt thereof. In a further aspect this invention provides a pharmaceutically acceptable salt of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one and a pharmaceutically acceptable carrier therefor. In another aspect this invention provides a pharmaceutical composition which comprises a cognition enhancing non-anxiolytic amount of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier therefor. Since said quinolinone is much more effective as an inverse agonist at GABAAO,5 than as an agonist at GABAA 1; α 2 or α 3 (e.g. >-20% as compared to about +5%) the dose required for cognition enhancement is readily differentiated from the higher dose required before anxiolytic or anti-depressant behaviour (if any) can take place. The salts of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one may be made by treatment with the required acid, for example in ethanolic solution. Favourably the salt is in isolated form and more favourably substantially pure. Preferably the salt is crystalline. DESCRIPTION 2-(4-Methoxyphenyl)-2,5-dihydro-pyrazolo[ ' 4 1 3-c1quinolin-3-one A mixture of ethyl 4-chloro-quinoline-3-carboxylate (10.18g, 0.043mol), 4-methoxyphenylhydrazine hydrochloride (8.45g, 0.048mol) and N-ethyldiisopropylamine (16.6ml, 0.096mol) in xylene (250ml) was de- oxygenated, using nitrogen, for 15 minutes. The mixture was heated at reflux, with stirring under nitrogen, for 2 hours, cooled, diluted with diethyl ether (100ml) and treated with water (100ml). After stirring for 30 minutes the mixture was filtered and the solid washed with diethyl ether (200ml) then stirred in water (250ml) at 70°C for 30 minutes. The solid was collected by filtration then dried in υacuo to give the title compound free base as a yellow solid (12. lg, 96%), mp 273-274°C (propan-2-ol), MS, ES + , m/z = 292 for (M+H) + , δ (500MHz,DMSO-d6) 3.78 (3H,s), 7.02 (2H,d,J=9Hz), 7.54 (lH,dd,Jι=J 2 =8Hz), 7.66 (lH,dd,J 1 =J 2 =8Hz), 8.09 (2H,d,J=9Hz), 8.21(lH,d,J=8Hz), 8.69(1H,5), 12.76 (lH,broad res.). EXAMPLE 1 2-(4-methoxyphenyl)-2,5-dihvdro-pyrazolor4,3-clquinolin-3-one hemi- ca psylate The free base of Description 1 (200mg, 0.687mmol) in ethanol/acetone (8ml, 1:1) at reflux was filtered and treated with a solution of (lS)-(+)-10-camphorsulphonic acid (160mg, 0.687mmol) in ethanol (2ml). The mixture was allowed to cool to room temperature, aged for 1 hour, then the title compound collected by filtration as a yellow solid (205mg), mp 240°-241°C. EXAMPLE 2 A sulphate salt was prepared exactly as described in Example 1 by replacing the camphorsulphonic acid by sulphuric acid (0.687mmol) m.pt 264-7°C. EXAMPLE 3 A scored tablet may be prepared comprising: 1. Compound of Ex.1 20mg 2. Lactose 120mg 3. Microcrystalline cellulose 40mg 4. Polyvinylpyrrolidone 5mg 5. Magnesium sterate 5mg

Claims: CLAIMS 1. Use of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for the enhancement of cognition. 2. Use according to claim 1 wherein the medicament is for the enhancement of cognition in a subject suffering from jAlzheimer's Disease. 3. A pharmaceutically acceptable salt of 2-(4-methoxyphenyl)- pyrazolo[4,3-c]quinolin-3-one and a pharmaceutically acceptable carrier therefor. 4. A pharmaceutical composition comprising a cognition enhancing non- anxiolytic amount of 2-(4-methoxyphenyl)- pyrazolo[4,3-c]quinolin-3-one or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier therefor. 5. A pharmaceutically acceptable acid addition salt of 2-4(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one with hydrochloric, sulphuric, hydrobromic, phosphoric, methane sulfonic, ethane sulfonic, camphor sulfonic, acetic, lactic, critic, tartaric, maleic, benzoic, propionic, succinic, furanic, gluconic or malic acid. 6. A salt according to claim 5 which is the hemi camphor sulfonate. 7. A method of treatment of a condition requiring the enhancement of cognition in a subject which comprises administering to the subject in need thereof a cognition enhancing amount of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one or a pharmaceutically acceptable salt thereof. 8. A process for preparing a pharmaceutically acceptable acid addition salt of 2-(4-methoxyphenyl)-pyrazolo[4,3-c]quinolin-3-one which comprises treating the aforementioned compound in ethanolic solution with the required acid.

Inventors: DAWSON GERARD RAPHAEL, MACLEOD ANGUS MURRAY, SEABROOK GUY RALPH, DAWSON, GERARD, RAPHAEL, MACLEOD, ANGUS, MURRAY, SEABROOK, GUY, RALPH
Applicants: DAWSON GERARD RAPHAEL, MACLEOD ANGUS MURRAY, MERCK SHARP & DOHME, SEABROOK GUY RALPH, DAWSON, GERARD, RAPHAEL, MACLEOD, ANGUS, MURRAY, MERCK SHARP & DOHME LIMITED, SEABROOK, GUY, RALPH
Application year: 1997
Main classification: A61K31
IPC codes: A61K31, A61P25, C07D471