Morpholino-n-ethyl ester derivative of an indole sPLA.sub.2 inhibitor

FIELD OF THE INVENTION
This invention relates to a novel prodrug form of sPLA.sub.2 inhibitor having exceptionally high bioavailability.
BACKGROUND OF THE INVENTION
The structure and physical properties of human non-pancreatic secretory phospholipase A.sub.2 (hereinafter called, "sPLA.sub.2 ") has been thoroughly described in two articles, namely, "Cloning and Recombinant Expression of Phospholipase A.sub.2 Present in Rheumatoid Arthritic Synovial Fluid" by Seilhamer, Jeffrey J.; Pruzanski, Waldemar; Vadas Peter; Plant, Shelley; Miller, Judy A.; Kloss, Jean; and Johnson, Lorin K.; The Journal of Biological Chemistry, Vol. 264, No. 10, Issue of April 5, pp. 5335-5338, 1989; and "Structure and Properties of a Human Non-pancreatic Phospholipase A.sub.2 " by Kramer, Ruth M.; Hession, Catherine; Johansen, Berit; Hayes, Gretchen; McGray, Paula; Chow, E. Pingchang; Tizard, Richard; and Pepinsky, R. Blake; The Journal of Biological Chemistry, Vol. 264, No. 10, Issue of April 5, pp. 5768-5775, 1989; the disclosures of which are incorporated herein by reference.
It is believed that sPLA.sub.2 is a rate limiting enzyme in the arachidonic acid cascade which hydrolyzes membrane phospholipids. Thus, it is important to develop compounds which inhibit sPLA.sub.2 mediated release of fatty acids (e.g., arachidonic acid) and are highly bioavailable in mammals, especially humans. Such compounds are of value in general treatment of conditions induced and/or maintained by overproduction of sPLA.sub.2 ; such as septic shock, adult respiratory distress syndrome, pancreatitis, trauma, bronchial asthma, allergic rhinitis, rheumatoid arthritis, osteoarthritis, etc.
Therapeutic agents that may be given orally are, in general, greatly preferred and have enhanced commercial potential because of their inherent ease of use.
Prodrugs are forms of therapeutic agents sometimes used to improve performance of known therapeutic agents. For example, mycophenolic acid is reported to be improved by conversion to its morpholino ethyl type prodrug (see, article, "Mycophenolate mofetil" by James J. Lipsky, The Lancet, Vol 348, Nov. 16, 1997, pg. 1357-1359).
U.S. Pat. No. 5,654,326 describes certain indole type sPLA.sub.2 inhibitors. In particular, this patent exemplifies the methyl ester of ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid.
It is desirable to develop more highly available sPLA.sub.2 inhibitors, particularly those suitable for oral administration.
SUMMARY OF THE INVENTION
This invention is the compound, ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester which is highly bioavailable by oral administration.
This invention is also a pharmaceutical formulation containing the novel compound of the invention.
This invention is also a method of inhibiting sPLA.sub.2 mediated release of fatty acid by contacting sPLA.sub.2 with the novel compound of the invention.
DETAILED DESCRIPTION OF THE INVENTION
THE 1H-INDOLE-3-GLYOXYLAMIDE COMPOUND OF THE INVENTION
The compound of the invention ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester; is represented by the structural formula (I); ##STR1##
The morpholino-N-ethyl ester (I) is an ester form of known sPLA.sub.2 inhibitor ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid represented by the structural formula (II), below; ##STR2## The compound of formula (II) is described in Example 9 of U.S. Pat. No. 5,654,326 (the disclosure of which is incorporated herein by reference) and European Patent Application No. 95302166.4, Publication No. 0 675 110 (publ., Oct. 4, 1995).
Prodrugs are derivatives of therapeutic agents which have chemically or metabolically cleavable groups and become under physiological conditions known compounds of therapeutic effectiveness.
It is a discovery of this invention that the compound of formula (I) is highly bioavailable upon oral administration compared to closely related ester type prodrugs.
SYNTHESIS OF THE COMPOUND OF THE INVENTION
The synthesis of ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester (compound of formula I, supra.) uses as starting material ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid or a salt thereof (compound of formula II, supra.). This starting material may be prepared by the reaction schemes or method of Example 9 of U.S. Pat. No. 5,654,326. Similar methods are shown in European Patent Application No. 95302166.4, Publication No. 0 675 110 (publ., Oct. 4, 1995).
Another method of making 1H-indole-3-glyoxylamide starting material of Formula II is described in U.S. patent application Ser. No. 09/105381, filed Jun. 26, 1998 and titled "Process for Preparing 4-substituted 1-H-Indole-3-glyoxyamides" the entire disclosure of which is incorporated herein by reference.
Other methods well known and recorded in the chemical literature may also be used for preparing the starting material.

EXAMPLE 1
Preparation of [[3-(2-Amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid, a compound represented by the formula (II): ##STR3##
Part A. Preparation of 2-Ethyl-4-methoxy-1H-indole.
A solution of 140 mL (0.18 mol) of 1.3M sec-butyl lithium in cyclohexane was added slowly to N-tert-butoxycarbonyl-3-methoxy-2-methylaniline (21.3 g, 0.09 mol) in 250 mL of THF keeping the temperature below -40.degree. C. with a dry ice-ethanol bath. The bath was removed and the temperature allowed to rise to 0.degree. C. and then the bath replaced. After the temperature had cooled to -60.degree. C., 18.5 g (0.18 mol) of N-methoxy-N-methylpropanamide in an equal volume of THF was added dropwise. The reaction mixture was stirred 5 minutes, the cooling bath removed and stirred an additional 18 hours. It was then poured into a mixture of 300 mL of ether and 400 mL of 0.5N HCl. The organic layer was separated, washed with water, brine, dried over MgSO.sub.4, and concentrated at reduced pressure to give 25.5 g of a crude of 1- [2- (tert-butoxycarbonylamino) -6-methoxyphenyl]-2-butanone. This material was dissolved in 250 mL of methylene chloride and 50 mL of trifluoroacetic acid and stirred for a total of 17 hours. The mixture was concentrated at reduced pressure and ethyl acetate and water added to the remaining oil. The ethyl acetate was separated, washed with brine, dried (MgSO.sub.4) and concentrated. The residue was chromatographed three times on silica eluting with 20% EtOAc/hexane to give 13.9 g of 2-ethyl-4-methoxy-1H-indole.
Analyses for C.sub.11 H.sub.13 NO:
Calculated: C, 75.40; H, 7.48; N, 7.99;
Found: C, 74.41; H, 7.64; N, 7.97.
Part B. Preparation of 2-Ethyl-4-methoxy-1-(phenylmethyl) -1H-indole.
2-Ethyl-4-methoxy-1H-indole (4.2 g, 24 mmol) was dissolved in 30 mL of DMF and 960 mg (24 mmol) of 60% NaH/minerial oil was added. After 1.5 hours, 2.9 mL(24 mmol) of benzyl bromide was added. After 4 hours, the mixure was diluted with water and extracted twice with ethyl acetate. The combined ethyl acetate was washed with brine, dried (MgSO.sub.4) and concentrated at reduced pressure. The residue was chromatographed on silica gel and eluted with 20% EtOAc/hexane to give 3.1 g (49% yield) of 2-ethyl-4-methoxy-1-(phenylmethyl)-1H-indole.
Part C. Preparation of 2-Ethyl-4-hydroxy-1-(phenylmethyl)-1H-indole.
3.1 g (11.7 mmol) of 2-ethyl-4-methoxy-1-(phenylmethyl)-1H-indole was O-demethylated by treating it with 48.6 mL of 1M BBr.sub.3 in methylene chloride with stirring at room temperature for 5 hours, followed by concentration at reduced pressure. The residue was dissolved in ethyl acetate, washed with brine and dried (MgSO.sub.4). After concentrating at reduced pressure, the residue was chromatographed on silica gel eluting with 20% EtOAc/hexane to give 1.58 g (54% yield) of 2-ethyl-4-hydroxy-1-(phenylmethyl)-1H-indole, mp, 86-90.degree. C.
Analyses for C.sub.17 H.sub.17 NO:
Calculated: C, 81.24; H, 6.82; N, 5.57;
Found: C, 81.08; H, 6.92; N, 5.41.
Part D. Preparation of [[2-Ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid methyl ester.
2-ethyl-4-hydroxy-1-(phenylmethyl)-1H-indole (1.56 g, 6.2 mmol) was added to a mixture of 248 mg (6.2 mmol) of 60% NaH/mineral oil in 20 mL DMF and stirred for 0.67 hour.
Then 0.6 mL(6.2 mmol) of methyl bromoacetate was added and stirring was continued for 17 hours. The mixture was diluted with water and extracted with ethyl acetate. The ethyl acetate solution was washed with brine, dried (MgSO.sub.4), and concentrated at reduced pressure. The residue was chromatographed on silica gel eluting with 20% EtOAc/hexane, to give 1.37 g (69% yield) of [[2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid methyl ester, 89-92.degree. C.
Analyses for C.sub.20 H.sub.21 NO.sub.3 :
Calculated: C, 74.28; H, 6.55; N, 4.33;
Found: C, 74.03; H, 6.49; N, 4.60.
Part E. Preparation of [[3-(2-Amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid methyl ester.
Oxalyl chloride (0.4 mL, 4.2 mmol) was added to 1.36 g (4.2 mmol) of [[2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid methyl ester in 10 mL of methylene chloride and the mixture stirred for 1.5 hours. The mixture was concentrated at reduced pressure and residue taken up in 10 mL of methylene chloride. Anhydrous ammonia was bubbled in for 0.25 hours, the mixture stirred for 1.5 hours and evaporated at reduced pressure. The residue was stirred with 20 mL of ethyl acetate and the mixture filtered. The filtrate was concentrated to give 1.37 g of a mixture of [[3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid methyl ester and ammonium chloride. This mixture melted at 172-187.degree. C.
Part F. Preparation of [[3-(2-Amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid.
A mixture of 788 mg (2 mmol) of [3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]-acetic acid methyl ester, 10 mL of In NaOH and 30 mL of MeOH is heated to maintain reflux for 0.5 hour, stirred at room temperature for 0.5 hour and concentrated at reduced pressure. The residue is taken up in ethyl acetate and water, the aqueous layer separated and made acidic to pH 2-3 with 1N HCl. The precipitate is filtered and washed with ethyl acetate to give 559 mg (74% yield) of [[3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl]oxy]acetic acid, mp, 230-234.degree. C.
Analyses for C.sub.21 H.sub.20 N.sub.2 O.sub.5 :
Calculated: C, 65.96; H, 5.80; N, 7.33;
Found: C, 66.95; H, 5.55; N, 6.99.
Beginning with the indole starting material of formula (II) prepared by the above method the ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester compound of the invention is prepared by esterification of the acid or salt form of the starting material. Any ester forming method which is conventional in the chemical arts may be used. A suitable procedure used to prepare the compound of the invention is as follows:
EXAMPLE 2
Preparation of ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester
In a flask containing 150 ml of methylene chloride was added with stirring 1.88 ml. (14.9 mmol) of 4-(2-chloroethyl)morpholine hydrochloride (available from Aldrich Chemical Co., Milwaukee, Wis. USA, Item No. C4,220-3), 3.07 g (14.9 mmol) dicylohexyl carbodiimide, 2.0 g (150 mmol) 1-hydroxybenzotriazole, and 5.65 g (14.9 mmol) of ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid. The slurry was stirred at room temperature for 20 hours then filtered. The resulting solution was washed once with saturated aqueous sodium bicarbonate solution. The organic phase was seperated, dried, filtered, and concentrated in vacuo to provide 7.0 g (95%) of the desired product of Formula I.
FORMULATIONS SUITABLE FOR USE IN THE METHOD OF THE INVENTION
The sPLA.sub.2 inhibitor of formula (I) used in the method of the invention is administered so as to make contact with sPLA.sub.2 in the body of the mammal being treated.
The preferred route of administration for the compound of this invention is orally, either as neat compound or as the active compound in a pharmaceutical formulation.
The sPLA.sub.2 inhibitor can be administered alone, but is generally administered with a pharmaceutical carrier or diluent selected on the basis of the chosen route of administration and standard pharmaceutical practice.
By "pharmaceutically acceptable" it is meant the carrier, diluent or excipient must be compatible with the formula (II) sPLA.sub.2 inhibitor ("active compound") in the formulation and not deleterious to the subject being treated.
For the pharmaceutical formulations any suitable carrier known in the art can be used. In such a formulation, the carrier may be a solid, liquid, or mixture of a solid and a liquid. A solid carrier can be one or more substances which may also act as flavoring agents, lubricants, solubilizers, suspending agents, binders, tablet disintegrating agents and encapsulating material.
Tablets for oral administration may contain suitable excipients such as calcium carbonate, sodium carbonate, lactose, calcium phosphate, together with disintegrating agents, such as maize, starch, or alginic acid, and/or binding agents, for example, gelatin or acacia, and lubricating agents such as magnesium stearate, stearic acid, or talc. In tablets the sPLA.sub.2 inhibitor is mixed with a carrier having the necessary binding properties in suitable proportions and compacted in the shape and size desired.
Sterile liquid form formulations include suspensions, emulsions, syrups and elixirs. The active compound can be dissolved or suspended in a pharmaceutically acceptable carrier, such as sterile water, saline, dextrose solution, sterile organic solvent or a mixture of both.
The active compound can be administered orally in solid dosage forms, such as capsules, tablets, and powders, or in liquid dosage forms, such as elixirs, syrups, and suspensions. It can also be administered parenterally, in sterile liquid dosage forms. It can also be administered by inhalation in the form of a nasal spray or lung inhaler. It can also be administered topically as an ointment, cream, gel, paste, lotion, solution, spray, aerosol, liposome, or patch. Dosage forms used to administer the active compound usually contain suitable carriers, diluents, preservatives, or other excipients, as described in Remington's Pharmaceutical Sciences, Mack Publishing Company, a standard reference text in the field.
Gelatin capsules may be prepared containing the active compound and powdered carriers, such as lactose, sucrose, mannitol, starch, cellulose derivatives, magnesium stearate, stearic acid, and the like. Similar diluents can be used to make compressed tablets and powders. Both tablets and capsules can be manufactured as sustained release products to provide for continuous release of medication over a period of hours. Compressed tablets can be sugar coated or film coated to mask any unpleasant taste and protect the tablet from the atmosphere, or enteric coated for selective disintegration in the gastrointestinal tract.
For parenteral solutions, water, a suitable oil, saline, aqueous dextrose (glucose), and related sugar solutions and glycols such as propylene glycol or polyethylene glycols are suitable carriers for parenteral solutions. Solutions for parenteral administration contain the active compound, suitable stabilizing agents, and if necessary, buffer substances. Anti-oxidizing agents such as sodium bisulfite, sodium sulfite, or ascorbic acid either alone or combined are suitable stabilizing agents. Also used are citric acid and its salts and sodium EDTA. In addition, parenteral solutions can contain preservatives, such as benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.
Formulations within the scope of this invention include the admixture of sPLA.sub.2 inhibitor with a therapeutically effective amount of any therapeutically effective co-agents, such as other sPLA.sub.2 inhibitors, leukotriene antagonists or cycloxygenase inhibitors for treating the disease target.
PROPORTION AND WEIGHT OF ACTIVE COMPOUNDS USED IN THE METHOD OF THE INVENTION
The compound of formula (I) may be used at a concentration of 0.1 to 99.9 weight percent of the pharmaceutical formulation.
Preferably the pharmaceutical formulation is in unit dosage form. The unit dosage form can be a capsule or tablet itself, or the appropriate number of any of these. The quantity of active compound in a unit dose of composition may be varied or adjusted from about 0.1 to about 1000 milligrams or more according to the particular treatment involved.
Compositions (dosage forms) suitable for internal administration contain from about 1 milligram to about 500 milligrams of active compound per unit.
Examples of useful pharmaceutical compositions and their proportions of ingredients are illustrated as follows:
Capsules: Capsules may be prepared by filling standard two-piece hard gelatin capsules each with 50 mg of powdered active compound, 175 mg of lactose, 24 mg of talc, and 6 mg of magnesium stearate.
Soft Gelatin Capsules: A mixture of active compound in soybean oil is prepared and injected by means of a positive displacement pump into gelatin to form soft gelatin capsules containing 50 mg of the active compound. The capsules are washed in petroleum ether and dried.
Tablets: Tablets may be prepared by conventional procedures so that the dosage unit is 50 mg of active compound, 6 mg of magnesium stearate, 70 mg of microcrystalline cellulose, 11 mg of cornstarch, and 225 mg of lactose. Appropriate coatings may be applied to increase palatability or delay absorption. Tablets for oral administration may contain suitable excipients such as calcium carbonate, sodium carbonate, lactose, calcium phosphate, together with disintegrating agents, such as maize, starch, or alginic acid, and/or binding agents, for example, gelatin or acacia, and lubricating agents such as magnesium stearate, stearic acid, or talc. The tablets preferably contain from about 1 to about 99 weight percent of the active ingredient which is the novel compound of this invention. Suitable solid carriers are magnesium carbonate, magnesium stearate, talc, sugar lactose, pectin, dextrin, starch, gelatin, tragacanth, methyl cellulose, sodium carboxymethyl cellulose, low melting waxes, and cocoa butter.
Suspensions: An aqueous suspension is prepared for oral administration so that each 5 ml contain 25 mg of finely divided active compound, 200 mg of sodium carboxymethyl cellulose, 5 mg of sodium benzoate, 1.0 g of sorbitol solution, U.S.P., and 0.025 mg of vanillin.
Injectables: A parenteral composition suitable for administration by injection is prepared by stirring 1.5% by weight of active compound in 10% by volume propylene glycol and water. The solution is sterilized by commonly used techniques.
Nasal Spray: An aqueous solution is prepared such that each 1 ml contains 10 mg of active compound, 1.8 mg methylparaben, 0.2 mg propylparaben and 10 mg methylcellulose. The solution is dispensed into 1 ml vials. The active compound may be used at a concentration of 0.1 to 99.9 weight percent of the formulation.
Aerosol formulations are capable of dispersing into particle sizes of from about 0.5 to about 10 microns and have sufficient sPLA2 inhibitor to achieve concentrations of the inhibitor on the airway surfaces of from about 10.sup.-10 to 10.sup.-2 moles per liter.
The dosage administered will, of course, vary depending upon known factors such as the pharmacodynamic characteristics of the particular agent, and its mode and route of administration; age, health, and weight of the recipient; nature and extent of symptoms, kind of concurrent treatment, frequency of treatment, and the effect desired. Usually a daily dosage of active compound can be about 0.1 to 200 milligrams per kilogram of body weight. Ordinarily 0.5 to 50, and preferably 1 to 25 milligrams per kilogram per day given in divided doses 1 to 6 times a day or in sustained release form is effective to obtain desired results.
In general, the sPLA.sub.2 inhibitor will be administered to a human so that a therapeutically effective amount is received. A therapeutically effective amount may coventionally be determined for an individual patient by administering the active compound in increasing doses and observing the effect on the patient.
Generally, the compound must be administered in a manner and a dose to achieve in the human a blood level concentration of sPLA.sub.2 inhibitor of from 10 to 3000 nanograms/ml, and preferably a concentration of 100 to 800 nanograms/ml.
The treatment regimen may be from a single dose to multiple doses taken for years. Oral dosing is preferred for patient convenience and tolerance. With oral dosing, one to four oral doses per day, each from about 0.01 to 25 mg/kg of body weight with preferred doses being from about 0.1 mg/kg to about 2 mg/kg.
Parenteral administration (particularly, intravenous administration) is often preferred in instances where rapid alleviation of patient distress is required. With parenteral administration doses of 0.01 to 100 mg/kg/day administered continuously or intermittently throughout the day may be used. For parenteral administation, the compound may be administered in a physiologic saline vehicle (e.g., 0.9% normal saline, 0.45% normal saline, etc.) a dextrose vehicle (e.g., 5% dextrose in water), or a combination of saline and dextrose vehicle (0.9% normal saline in 5% dextrose).
USE AND PROPORTION OF ACTIVE COMPOUND IN THE METHOD OF THE INVENTION
Another aspect of this invention is a method for treating septic shock, adult respiratory distress syndrome, panceatitus, trauma, bronchial asthma, allergic rhinitis, rheumatoid arthritis, stroke, acute bronchitis, chronic bronchitis, acute bronchiolitis, chronic bronchiolitis, osteoarthritis, gout, spondylarthropathris, ankylosing spondylitis, Reiter's syndrome, psoriatic arthropathy, enterapathric spondylitis, juvenile arthropathy, juvenile ankylosing spondylitis, reactive arthropathy, infectious or post-infectious arthritis, gonoccocal arthritis, tuberculous arthritis, viral arthritis, fungal arthritis, syphilitic arthritis, Lyme disease, arthritis associated with "vasculitic syndromes", polyarteritis nodosa, hypersensitivity vasculitis, Luegenec's granulomatosis, polymyalgin rheumatica, joint cell arteritis, calcium crystal deposition arthropathris, pseudo gout, non-articular rheumatism, bursitis, tenosynomitis, epicondylitis (tennis elbow), carpal tunnel syndrome, repetitive use injury, neuropathic joint disease (charco and joint), hemarthrosis (hemarthrosic), Henoch-Schonlein Purpura, hypertrophic osteoarthropathy, multicentric reticulohistiocytosis, surcoilosis, hemochromatosis, sickle cell disease and other hemoglobinopathries, hyperlipo proteineimia, hypogammaglobulinemia, hyperparathyroidism, acromegaly, familial Mediterranean fever, Behat's Disease, systemic lupus erythrematosis, hemophilia, relapsing polychondritis, and cystic fibrosis. The method comprises administering to a human having such diseases a therapeutically effective amount of the compound formula (I).
The compound of the invention, ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester is believed to be a prodrug that transforms in the body of a mammal into ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid. This acid is a known sPLA.sub.2 inhibitor as shown by the following data (Assays 1 & 2 from U.S. Pat. No. 5,654,326):
Assay 1
A chromogenic assay procedure was used to evaluate ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid as an inhibitor of recombinant human secreted phospholipase A.sub.2. A general description of this assay method is found in the article, "Analysis of Human Synovial Fluid Phospholipase A.sub.2 on Short Chain Phosphatidylcholine-Mixed Micelles: Development of a Spectrophotometric Assay Suitable for a Microtiterplate Reader", by Laure J. Reynolds, Lori L. Hughes, and Edward A Dennis, Analytical Biochemistry, 204, pp. 190-197, 1992 (the disclosure of which is incorporated herein by reference):
TABLE I______________________________________ Inhibition of human secreted PLA.sub.2 IC.sub.50 .+-. mean deviation Compound of (3-4 tests)______________________________________formula (II) 9.00 .+-. 1.73 nM______________________________________
Conclusion: The compound of formula (II) is highly active in inhibiting sPLA.sub.2.
Assay 2
A guinea pig lung tissue procedure was used evaluate ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic (compound of formula II) as an inhibitor of recombinant human secreted phospholipase A.sub.2.
To estimate the drug-induced suppression of the maximal responses, sPLA.sub.2 responses (10 ug/ml) were determined in the absence and presence of drug, and percent suppression was calculated for each pair of tissues.
Results of Human Secreted Phospholipase A.sub.2 Inhibition Tests on guinea pig lung tissue
TABLE II______________________________________ Tissue test secreted PLA.sub.2 Compound of Apparent K.sub.B nM______________________________________formula (II) 88.7 .+-. 18.2______________________________________
The bioavailability of the compound of the invention, ((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester was determined using a Monkey Pharmacokinetic Study:
Data Analysis:
Plasma was assayed by HPLC to measure concentrations of the different sPLA.sub.2 inhibitors (measured as free acids).
Cmax (maximal plasma concentrations), and AUC values were determined from the mean plasma concentration-time profiles. The results of the study are shown in Table 3, below:
TABLE 3______________________________________ Cmax AUC (0-12 h) AUC (0-24 h) Compound ng/ml Tmax hours ng*h/ml ng*h/ml______________________________________1 3296 2.0 11919 13161 2 615 3.3 5140 8730 3 245 2.0 1675 3404 4 1604 2.0 5131 5425 5 200 2.0 1356 2038______________________________________
Compound Nos.:
1=((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester
2=((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid methyl ester
3=((3-(2-amino-1,2-dioxoethyl)-2-ethyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid ethyl ester
4=((3-(2-amino-1,2-dioxoethyl)-2-methyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid morpholino-N-ethyl ester
5=((3-(2-amino-1,2-dioxoethyl)-2-methyl-1-(phenylmethyl)-1H-indol-4-yl)oxy)acetic acid methyl ester
Table 3 shows that compound 1, the morpholino-N-ethyl ester, the compound of the invention is unexpectedly more bioavailable than other esters of the parent sPLA.sub.2 inhibitor of formula II and also more bioavailable than the 2-methyl homolog of the parent sPLA2 inhibitor of formula II.
While the present invention has been illustrated above by certain specific embodiments, it is not intended that these specific examples should limit the scope of the invention as described in the appended claims.

Number	Date	Country
WO9842343	Oct 1998	WOX
WO 9921559	May 1999	WOX
WO 9925339	May 1999	WOX

Morpholino-n-ethyl ester derivative of an indole sPLA.sub.2 inhibitor

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