Field of the Invention

The present invention relates to novel N-substituted azaheterocyclic carbox¬ ylic acids and esters thereof in which a substituted alkyl chain forms part of the N-substituent or salts thereof, to methods for their preparation, to compositions containing them, and to their use for the clinical treatment of painful, hyperalgesic and/or inflammatory conditions in which C-fibers play a pathophysiological role by eliciting neurogenic pain or inflammation. The invention also relates to the use of the present compounds for the treatment of insulin resistance in non-insulin-dependent diabetes mellitus (NIDDM) or aging, the present compounds knowing to interfere with neuropeptide con¬ taining C-fibres and hence inhibit the secretion and circulation of insulin an¬ tagonizing peptides like CGRP or amylin.

Background of the Invention

The nervous system exerts a profound effect on the inflammatory response. Antidromic stimulation of sensory nerves results in localized vasodilation and increased vascular permeability (Janecso et al. Br. J. Pharmacol. 1967, 31 , 138-151 ) and a similar response is observed following injection of peptides known to be present in sensory nerves. From this and other data it is postu- Iated that peptides released from sensory nerve endings mediate many inflammatory responses in tissues like skin, joint, urinary tract, eye, menin- ges, gastro-intestinal and respiratory tracts. Hence inhibition of sensory nerve peptide release and/or activity, may be useful in treatment of, for example arthritis, dermatitis, rhinitis, asthma, cystitis, gingivitis, thrombo-phlelitis, glaucoma, gastro-intestinal diseases or migraine.

Further, the potent effects of CGRP on skeletal muscle glycogen synthase ac¬ tivity and muscle glucose metabolism, together with the notion that this peptide is released from the neuromuscular junction by nerve excitation, suggest that CGRP may play a physiological role in skeletal muscle glucose metabolism by directing the phosphorylated glucose away from glycogen storage and into the glycolytic and oxidative pathways (Rossetti et al. Am. J. Physiol. 264, E1 -E10, 1993). This peptide may represent an important physiological modulator of intracellular glucose trafficking in physiological conditions, such as exercise, and may also contribute to the decreased insulin action and skeletal muscle glycogen synthase in pathophysiological condi¬ tions like NIDDM or aging-associated obesity (Melnyk et al. Obesity Res. 3, 337-344, 1995) where circulating plasma levels of CGRP are markedly increased. Hence inhibition of release and/or activity of the neuropeptide CGRP may be useful in the treatment of insulin resistance related to type 2 diabetes or aging.

In US Patent No. 4,383,999 and No. 4,514,414 and in EP 236342 as well as in EP 231996 some derivatives of N-(4,4-disubstituted-3-butenyl)- azaheterocyclic carboxylic acids are claimed as inhibitors of GABA uptake. In EP 342635 and EP 374801 , N-substituted azaheterocyclic carboxylic acids in which an oxime ether group and vinyl ether group forms part of the N- substituent respectively are claimed as inhibitors of GABA uptake. Further, in WO 9107389 and WO 9220658, N-substituted azacyclic carboxylic acids are claimed as GABA uptake inhibitors. EP 221572 claims that 1 -aryloxyalkyl- pyridine-3-carboxylic acids are inhibitors of GABA uptake.

Description of the Invention

The present invention relates to novel N-substituted azaheterocyclic car¬ boxylic acids and esters thereof of formula I

wherein R ¹ and R ² independently are hydrogen, halogen, trifluoromethyl, hydroxy, C _β -alkyl, C _β -alkoxy, -NR ⁷ R ⁸ or -SO ₂ NR ⁷ R ⁸ wherein R ⁷ and R ⁸ independently are hydrogen or C^-alky!; and

X is completion of an optional bond, -C(R ⁹ R ¹⁰ )-, -CH = CH-CH ₂ -, -CH ₂ -

CH = CH-, -CH ₂ -(C = O)-, -(C = O)-CH ₂ -, -CH ₂ CH ₂ CH ₂ -, -N(R ¹¹ )-(C = O)-, -(C = O)-

N(R ¹¹ )-, -OCH ₂ -, -CH ₂ O-, -SCH ₂ -, -CH ₂ S-, -(C = O)-, -N(R ¹² )-, -CH ₂ N(R ¹² )-, -

N(R ¹² )CH ₂ -, -N(CH ₃ )SO ₂ -, -SO ₂ N(CH ₃ )-, -CH(R ¹⁰ )CH ₂ - or

-CH ₂ CH(R ¹⁰ )- wherein R ⁹ is hydrogen or C^-alky!, and R ¹⁰ is C^-alky! or phenyl optionally substituted with halogen, CF ₃ , hydroxy, C^-alky! or C,. _β - alkoxy, and R ¹¹ and R ¹² independently are hydrogen or and

Y is -O-, -S(O) _q - wherein q is 0, 1 or 2, or -N(R ¹³ )- wherein R ¹³ is hydrogen or

C-,. _β -alkyl; and s is 0 or 1 and p is 0 or 1 provided that s and p must not be 0 at the same time; and r is 1 , 2, 3 or 4; and

Z is selected from

wherein n is 1 or 2; and

R ³ is -(CH ₂ ) _m OH or -{CH ₂ ) _t COR ⁴ wherein m is 0, 1 , 2, 3, 4, 5 or 6 and t is 0 or

1 and wherein R ⁴ is -OH, -NH ₂ , -NHOH or C^-alkoxy; and

R ⁵ is hydrogen, halogen, trifluoromethyl, hydroxy, C^-alkyl or C^-alkoxy; and

R ^β is hydrogen, or phenyl optionally substituted with halogen, trifluoromethyl, hydroxy, C^-alky! or C _e -alkoxy; and

R ¹⁴ is hydrogen or C^-alkyl; and

_ is optionally a single bond or a double bond; or a pharmaceutically acceptable salt thereof.

The compounds of formula I may exist as geometric and optical isomers and all isomers and mixtures thereof are included herein. Isomers may be separ¬ ated by means of standard methods such as chromatographic techniques or fractional crystallization of suitable salts.

Preferably, the compounds of formula I exist as the individual geometric or optical isomers.

The compounds according to the invention may optionally exist as pharma¬ ceutically acceptable acid addition salts or - when the carboxylic acid group is not esterified - as pharmaceutically acceptable metal salts or - optionally

alkylated - ammonium salts.

Examples of such salts include inorganic and organic acid addition salts such as hydrochloride, hydrobromide, sulphate, phosphate, acetate, fumarate, maleate, citrate, lactate, tartrate, oxalate or similar pharmaceutically accept¬ able inorganic or organic acid addition salts, and include the pharmaceutically acceptable salts listed in Journal of Pharmaceutical Science, .66, 2 (1977) which are hereby incorporated by reference.

The term "C.,. _β -alkyl" as used herein, alone or in combination, refers to a straight or branched, saturated hydrocarbon chain having 1 to 6 carbon atoms such as e.g. methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, n-hexyl, 4- methylpentyl, neopentyl, n-hexyl, 1 ,2-dimethylpropyl, 2,2-dimethylpropyl and 1 ,2,2-trimethylpropyl.

The term as used herein, alone or in combination, refers to a straight or branched monovalent substituent comprising a C^-alkyl group linked through an ether oxygen having its free valence bond from the ether oxygen and having 1 to 6 carbon atoms e.g. methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentoxy.

The term "halogen" means fluorine, chlorine, bromine or iodine.

As used herein, the term "patient" includes any mammal which could benefit from treatment of neurogenic pain or inflammation or insulin resistance in NIDDM. The term particularly refers to a human patient, but is not intended to be so limited.

It has been demonstrated that the novel compounds of formula I inhibit

neurogenic inflammation which involves the release of neuropeptides from peripheral and central endings of sensory C-fibres. Experimentally this can be demonstrated in animal models of formalin induced pain or paw oedema (Wheeler and Cowan, Agents Actions 1991 , 34, 264-269) in which the novel compounds of formula I exhibit a potent inhibitory effect. Compounds of formula I may be used to treat all painful, hyperalgesic and/or inflammatory conditions in which C-fibers play a pathophysiological role by eliciting neurogenic pain or inflammation, i.e.: Acutely painful conditions exemplified by migraine, postoperative pain, burns, bruises, post-herpetic pain (Zoster) and pain as it is generally associated with acute inflammation; chronic, painful and/or inflammatory conditions exemp¬ lified by various types of neuropathy (diabetic, post-traumatic, toxic), neural¬ gia, rheumatoid arthritis, spondylitis, gout, inflammatory bowel disease, prostatitis, cancer pain, chronic headache, coughing, asthma, chronic pancreatitis, inflammatory skin disease including psoriasis and autoimmune dermatoses, osteoporotic pain.

Further, it has been demonstrated that the compounds of general formula I improves the glucose tolerance in diabetic ob/ob mice and that this may result from the reduced release of CGRP from peripheral nervous endings. Hence the compounds of general formula I may be used in the treatment of NIDDM as well as aging-associated obesity. Experimentally this has been demonstrated by the subcutaneous administration of glucose into ob/ob mice with or without previous oral treatment with a compound of general formula

The compounds of formula I may be prepared by the following method:

(II)

A compound of formula II wherein R\ R ² , X, Y, p, s and r are as defined above and W is a suitable leaving group such as halogen, p-toluene sulphonate or mesylate may be reacted with an azaheterocyclic compound of formula III wherein Z is as defined above. This alkylation reaction may be carried out in a solvent such as acetone, dibutylether, 2-butanone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran (THF) or toluene in the presence of a base e.g. sodium hydride and a catalyst, e.g. an alkali metal iodide at a temperature up to reflux temperature for the solvent used for e.g. 1 to 120 h. If esters have been prepared in which R ⁴ is alkoxy, compounds of formula I wherein R ⁴ is OH may be prepared by hydrolysis of the ester group, preferably at room temperature in a mixture of an aqueous alkali metal hydroxide solution and an alcohol such as methanol or ethanol, for example, for about 0.5 to 6 h.

Compounds of formula II and III may readily be prepared by methods familiar to those skilled in the art.

Under certain circumstances it may be necessary to protect the intermediates used in the above methods e.g. a compound of formula III with suitable protecting groups. The carboxylic acid group can, for example, be esterified.

Introduction and removal of such groups is described in "Protective Groups in Organic Chemistry" J.F.W. McOrnie ed. (New York, 1973).

Pharmacological Methods

Release of neuropeptides from pheripheral and central endings of sensory C-fibers

Values for in vivo inhibition of formalin induced pain or oedema for the com¬ pounds of the present invention were assessed in mice essentially by the method of Wheeler-Aceto and Cowan (Agents Action 1991 , 34, 265-269).

About 20 g NMRI female mice were injected 20 μ\ 1 % formalin into the left hind paw. The animals were then placed on a heated (31 °C) table, and the pain response was scored. After 1 h they were killed and bled. Left and right hind paws were removed and the weight difference between the paws was used as indication of the oedema response of the formalin injected paw.

Reduced release of CGRP from pheripheral nervous endings

ob/ob female mice, 16 weeks of age, where injected glucose (2g/kg) subcutane- ously. At times hereafter blood glucose was determined in tail venous blood by the glucose oxidase method. At the end of the study the animals were decapita¬ ted and trunck blood collected. Immunoreactive CGRP was determined in plasma by radio-immuno-assay. Two groups of animals were used. The one group was vehicle treated, whereas the other group received a compound of formula I via drinking water (100 mg/l) for five days before the test.

For the above indications the dosage will vary depending on the compound of formula I employed, on the mode of administration and on the therapy desired.

However, in general, satisfactory results are obtained with a dosage of from about 0.5 mg to about 1000 mg, preferably from about 1 mg to about 500 mg

of compounds of formula I, conveniently given from 1 to 5 times daily, optionally in sustained release form. Usually, dosage forms suitable for oral administration comprise from about 0.5 mg to about 1000 mg, preferably from about 1 mg to about 500 mg of the compounds of formula I admixed with a pharmaceutical carrier or diluent.

The compounds of formula I may be administered in a pharmaceutically accept¬ able acid addition salt form or where possible as a metal or a lower alkylammo- nium salt. Such salt forms exhibit approximately the same order of activity as the free base forms.

This invention also relates to pharmaceutical compositions comprising a com¬ pound of formula I or a pharmaceutically acceptable salt thereof and, usually, such compositions also contain a pharmaceutical carrier or diluent. The composi¬ tions containing the compounds of this invention may be prepared by conven¬ tional techniques and appear in conventional forms, for example capsules, tablets, solutions or suspensions.

The pharmaceutical carrier employed may be a conventional solid or liquid carrier. Examples of solid carriers are lactose, terra alba, sucrose, talc, gelatin, agar, pectin, acacia, magnesium stearate and stearic acid. Examples of liquid carriers are syrup, peanut oil, olive oil and water.

Similarly, the carrier or diluent may include any time delay material known to the art, such as glyceryl monostearate or glyceryl distearate, alone or mixed with a wax.

If a solid carrier for oral administration is used, the preparation can be tabletted, placed in a hard gelatin capsule in powder or pellet form or it can be in the form of a troche or lozenge. The amount of solid carrier will vary widely but will usually be from about 25 mg to about 1 g. If a liquid carrier is used, the prepara-

tion may be in the form of a syrup, emulsion, soft gelatin capsule or sterile injectable liquid such as an aqueous or non-aqueous liquid suspension or solution.

Generally, the compounds of this invention are dispensed in unit dosage form comprising 50-200 mg of active ingredient in or together with a pharmaceuti¬ cally acceptable carrier per unit dosage.

The dosage of the compounds according to this invention is 1 -500 mg/day, e.g. about 100 mg per dose, when administered to patients, e.g. humans, as a drug.

A typical tablet which may be prepared by conventional tabletting techniques contains

Core:

Active compound (as free compound 100 mg or salt thereof)

Colloidal silicon dioxide (Areosil ^* ) 1 .5 mg Cellulose, microcryst. (Avicel ^* ) 70 mg

Modified cellulose gum (Ac-Di-Sol ^* ) 7.5 mg

Magnesium stearate

Coating:

HPMC approx. 9 mg ^" Mywacett ^* 9-40 T approx. 0.9 mg

"Acylated monoglyceride used as plasticizer for film coating.

The route of administration may be any route which effectively transports the active compound to the appropriate or desired site of action, such as oral or parenteral e.g. rectal, transdermal, subcutaneous, intranasal, intramuscular,

topical, intravenous, intraurethral, ophthalmic solution or an ointment, the oral route being preferred.

EXAMPLES

The process for preparing compounds of formula I and preparations containing them is further illustrated in the following examples, which, however, are not to be construed as limiting.

Hereinafter, TLC is thin layer chromatography and THF is tetrahydrofuran, CDCI ₃ is deuterio chloroform and DMSO-d _β is hexadeuterio dimethylsulfoxide. The structures of the compounds are confirmed by either elemental analysis or NMR, where peaks assigned to characteristic protons in the title compounds are presented where appropriate. ¹ H-NMR shifts (<5 _H ) are given in parts per million (ppm). M.p. is melting point and is given in °C and is not corrected. Column chromatography was carried out using the technique described by W.C. Still et al, J. Org. Chem. (1978), 43, 2923-2925 on Merck silica gel 60 (Art. 9385). Compounds used as starting materials are either known compounds or com¬ pounds which can readily be prepared by methods known per se.