CN1190889A - Zwitterionic forms of trovafloxacin - Google Patents

Abstract

A zwitterionic form of trovafloxacin having formula (I) selected from the group consisting of its crystalline hygroscopic and non-hygroscopic polymorphs and pentahydrate and methods for their preparation. The invention further relates to methods of using, and pharmaceutical compositions comprising, the compounds of the invention for treatment of bacterial infections in mammals.

Description

Zwitterionic form of trofloxacin

The present invention relates to naphthyridone antibiotic trovafloxacin. More particularly, the present invention relates to polymorphs and pentahydrates of the zwitterionic form of trofloxacin having formula I below, and processes for their preparation. The invention also relates to methods of using the compounds of the invention and pharmaceutical compositions comprising the compounds of the invention for the treatment of bacterial infections in mammals. The above-mentioned patents are assigned together with this application.

The antibacterial activity of the aforementioned naphthvridone antibiotics is documented in U.S. Patent Nos. 5,164,402 ['402 patent] and 5,229,396 issued on 11/17/92 and 7/20/93 respectively, the disclosures of which are fully incorporated herein by reference . The above-mentioned patents are assigned together with this application.

The zwitterionic form of trofloxacin can be administered as a suspension.

它选自：A first embodiment of the present invention provides a zwitterionic crystalline form of trofloxacin having the formula I:

It is selected from:

a) Non-hygroscopic first polymorph PI exhibiting the following characteristic X-ray powder diffraction pattern number of peaks 1 2 3 4 5 6 7 8 9 2_θ_(°)Cu 6.9 9.8 11.3 12.0 13.9 16.1 16.6 17.1 17.4 d distance 12.7 9.0 7.9 7.4 6.4 5.5 5.4 5.2 5.1 number of peaks 10 11 12 13 14 15 16 17 2_θ_(°)Cu 19.7 22.9 23.6 24.9 25.4 25.9 27.7 29.5 d distance 4.5 3.9 3.8 3.6 3.5 3.4 3.2 3.0 b) hygroscopic second polymorphic form PII exhibiting the following characteristic X-ray powder diffraction pattern number of peaks 1 2 3 4 5 6 7 8 2_θ_(°)Cu 8.4 9.5 10.2 14.7 16.8 17.9 22.6 26.1 d distance 10.6 9.3 8.7 6.0 5.3 5.0 3.9 3.4 and c) pentahydrate, trofloxacin zwitterion pentahydrate exhibiting the following characteristic X-ray powder diffraction pattern number of peaks 1 2 3 4 5 6 7 8 9 2_θ_(°)Cu 6.6 8.6 12.7 13.3 15.9 18.6 19.2 20.1 21.0 d distance 13.3 10.3 7.0 6.6 5.5 4.8 4.6 4.4 4.2 number of peaks 10 11 12 13 14 15 16 17 2_θ_(°)Cu 22.5 22.9 23.6 24.9 25.4 25.9 27.7 29.5 d distance 4.0 3.9 3.8 3.6 3.5 3.4 3.2 3.0

A second embodiment of the present invention relates to a process for the preparation of the zwitterion of trofloxacin of formula I selected from the non-hygroscopic polymorph PI, the hygroscopic polymorph PII and its pentahydrate as described above things, including:

A procedure for treating an aqueous suspension of a metastable form of a compound of formula I:

1) using a non-polar solvent, followed by azeotropic removal of residual water and vacuum drying to form the hygroscopic polymorph PII exhibiting the characteristic X-ray diffraction pattern as recited in claim 1;

2) using a polar solvent, followed by azeotropic removal of residual water and vacuum drying; or

3) air drying the residue with water and at elevated temperature, removing the mother liquor and air drying the residue at room temperature to a constant weight to form the pentahydrate; or

B) Treatment of the hygroscopic second polymorph PII with refluxing polar solvent to form the non-hygroscopic first polymorph PI.

A third embodiment of the present invention provides a process for the preparation of the zwitterionic metastable form of trofloxacin of formula I by

a) Treating the acid salt of trofloxacin with a base at elevated temperature, raising the pH of the mixture to between 7.5 and 8.5, removing the mother liquor, washing the crystals with water and drying the crystals under vacuum at about 35°C to about 40°C ;or

其中A是H或胺保护基团如叔-丁氧基羰基、苄氧基羰基、(C₁-C₆)烷基羰基和苄基；和b) Treatment of compounds of formula II

wherein A is H or an amine protecting group such as tert-butoxycarbonyl, benzyloxycarbonyl, (C ₁ -C ₆ )alkylcarbonyl and benzyl; and

B is H or a carboxylic acid protecting group selected from benzyl, tert-butyl and (C ₁ -C ₆ )alkyl; deprotecting agent with amine and/or carboxylic acid, respectively.

A fourth embodiment of the present invention provides a method of treating a bacterial infection in a mammal, comprising administering to said mammal a bacterial infection therapeutically effective amount of a compound of formula I as described above.

The fifth embodiment of the present invention provides a composition for treating bacterial infection in mammals, which comprises a therapeutically effective amount of the compound of formula I and a pharmaceutically acceptable carrier.

The present invention relates to a compound comprising a stable zwitterionic form of the antibiotic trofloxacin of formula I: More particularly, it relates to compounds of formula I selected from:

a) a non-hygroscopic first polymorph PI exhibiting a characteristic X-ray powder diffraction pattern as described above;

b) hygroscopic second polymorphic form PII exhibiting a characteristic X-ray powder diffraction pattern as described above;

and c) pentahydrate, trofloxacin zwitterion pentahydrate exhibiting the characteristic X-ray powder diffraction pattern as described above.

The present invention also relates to the preparation of compounds of formula I, as shown in the following schemes.

Flowchart 1

两性离子的亚稳定形式Flowchart 2

metastable form of the zwitterion

Trofloxacin salt I as shown in scheme 1, wherein, X is an anion, and it is selected from those by inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; Organic acid such as sulfonic acid, for example, benzenesulfonic acid (besylic), p-toluenesulfonic acid (PTSA, tosylic), methanesulfonic acid (MSA, methylic) and trifluoromethanesulfonic acid (triflic), etc.; and carboxylic acids, such as acetic acid, propionic acid, benzoic acid, citric acid, the anions formed by tartaric acid, maleic acid, fumaric acid, succinic acid and malic acid, by raising the pH of a slurry containing Compound 1 to about 7.5 and 8.5, and transformed into the metastable zwitterionic form 2. A preferred salt is the methanesulfonate. Bases useful in the practice of this aspect of the invention include inorganic bases such as alkali or alkaline earth hydroxides, carbonates and bicarbonates and organic bases such as tri( _C1 - _C6 )alkylamines, pyridine and morpholine. A preferred aqueous base is saturated sodium bicarbonate. The wet product was then vacuum dried to constant weight at a temperature of about 35 to 40°C.

Alternatively, as shown in Scheme 2, compound 2 can be prepared directly from the protected precursor 6 of trofloxacin salt 1 of formula II:

wherein A is H or an amine protecting group such as tert-butoxycarbonyl, benzyloxycarbonyl, (C ₁ -C ₆ )alkylcarbonyl and benzyl; and

B is H or a carboxylic acid protecting group selected from benzyl, tert-butyl and (C ₁ -C ₆ )alkyl; amine and/or carboxylic acid are used as deprotecting agents, respectively.

The preferred compound 6, where A is H and B is ethyl, is converted to compound 2 by treatment with sodium hydroxide in a polar solvent at elevated temperature, preferably methanol and temperature reflow temperature. The pH of the solution was then adjusted to between about 6.5 and 8.0 with dilute hydrochloric acid, and then the pH was adjusted to between about 7.5 and 8.5 by adding saturated aqueous NaHCO ₃ , and the product was recovered as indicated above.

The metastable trofloxacin zwitterion 2 is converted to the hygroscopic polymorph PII,4 by treatment with a non-polar solvent such as a hydrocarbon, preferably hexane. Residual water was removed azeotropically and the product was dried under vacuum at about 35°C to about 40°C. Solvents for the azeotropic removal of water include non-polar aliphatic hydrocarbons such as hexane and octane, and aromatic hydrocarbons such as benzene and toluene, the preferred solvents are aliphatic hydrocarbons, most preferably hexane.

Treatment of compound 2 with a polar solvent, followed by azeotropic removal of water and vacuum drying at about 30°C to about 40°C can prepare the non-hygroscopic polymorph PI3. Polar solvents used for this transformation include (C ₂ -C ₆ ) Alkyl carboxylic acid (C ₁ -C ₆ ) alkyl ester and (C ₁ -C ₆ ) alkanol and the like, the preferred solvent is ethyl acetate.

Alternatively, as described above, compound 3 can be prepared by treating compound 4 with refluxing polar solvent, the preferred solvent being ethyl acetate.

The pentahydrate of the compound of Formula I, Compound 5, was prepared by air drying wet crystals of Compound 1 at room temperature until constant weight was reached. Alternatively, compound 5 can be prepared by treating compound 4 with water until constant moisture uptake is achieved. Exposure of compound 3 to water does not convert compound 5.

The antibacterial compounds of the present invention, i.e. polymorphic form PI, polymorphic form PII and pentahydrate (hereinafter referred to as "active compound"), are useful in the treatment of animals and humans with a broad spectrum of bacterial infections, particularly for Treat Gram-positive bacteria.

The active compounds can be administered alone, but will generally be administered in admixture with a pharmaceutical carrier selected with regard to the intended route of administration and standard administration practice, for example, they can be administered orally or with excipients containing starch or lactose. or in capsule form, either alone or in admixture with excipients, or in the form of elixirs or suspensions with flavoring or coloring agents. For animals, they may advantageously be included in the animal's food or drinking water at a concentration of from about 5 to about 5000 ppm, preferably from about 25 to about 500 ppm. They can be injected parenterally, e.g. intramuscularly, intravenously or subcutaneously, and for parenteral administration they can preferably be used in the form of sterile aqueous solutions containing other solutes such as sufficient salt or glucose to render the solution isotonic . For animals, the compound of formula I can be administered intramuscularly or subcutaneously at dosage levels of about 0.1 to about 50 mg/kg/day, advantageously about 0.2 to about 10 mg/kg/day, if administered once a day or up to three divided doses .

The active compounds of the present invention can be administered to humans by oral or parenteral routes for the treatment of bacterial diseases at a dosage level of about 0.1 to 500 mg/kg/day, advantageously about 0.5 to 50 mg/kg/day, in a once-daily dose Or up to three divided doses. For intramuscular or intravenous administration, dosage levels are about 0.1-200 mg/kg/day, advantageously 0.5-50 mg/kg/day, intramuscular administration may be in one dose or up to three divided doses, intravenous administration may include continuous trickle. Variations will be necessary with respect to the weight and condition of the subject being treated and the particular route of administration chosen, as will be known to those of ordinary skill in the art.

The antibacterial activity of the compounds of the present invention was tested using the replica gene technique according to Steers, which is a standard in vitro test method and described in E. Steers et al., Antibiotics and Chemotherapy, 9, 307, (1959).

The following examples demonstrate the methods and compounds of the invention. However, it should be understood that the present invention is not limited to these particular Examples.

Example 1

Trofloxacin zwitterion, metastable form

A. Trofloxacin mesylate (prepared according to Example 13B of the '402 patent) (20 g) was stirred with deionized water (100 mL). The crystal slurry was heated to about 50°C and saturated sodium bicarbonate solution was added to adjust the pH of the slurry to about 8.0. The slurry was maintained at about 50°C for 30 minutes, cooled to about 25°C and stirred at this temperature for 30 minutes. The crystals were isolated by filtration and washed with deionized water (27ml). The wet crystals were suspended in deionized water (100 ml) and stirred at about 50 °C for about 1 hour; the crystals were filtered from the mother liquor, washed with deionized water (about 27 ml) and dried under vacuum at about 40 °C to constant weight, This yielded the title product which by analysis contained 2.5% residual water, product 16.25 g, 97%.

B. Ethyl ester of trofloxacin (prepared according to the method of co-pending U.S. patent application 08/490827, filed on June 15, 1995, the contents of which are fully incorporated herein by reference, the above-mentioned patent and this (apply for transfer together) (10 g) was stirred with methanol (75 ml), water (25 ml) and sodium hydroxide tablets (1.8 g). The reaction mixture was heated to reflux at about 72°C to form a solution, the solution was cooled to about 25°C and the pH was adjusted to about 7.5 by adding 6N hydrochloric acid to form a slurry, saturated sodium bicarbonate solution (50 mL) was added and the slurry was Stir at about 25°C for 30 minutes. The title product was isolated and washed with water (20 mL) and dried under vacuum at about 45°C to yield product 7.72 g, 82.5%.

Example 2

Trofloxacin zwitterionic polymorph PI (non-hygroscopic form)

Trofloxacin mesylate (75 g) was stirred with deionized water (375 ml), the crystal slurry was heated to about 50° C. and the pH of the slurry was adjusted to about 8.0 by adding saturated sodium bicarbonate solution, The temperature of the slurry was maintained at about 50°C for 30 minutes, cooled to about 25°C and stirred at this temperature for 30 minutes. The crystals were separated by filtration and washed with deionized water (100 ml), the wet crystals were suspended in deionized water (375 ml) and stirred at about 50° C. for 1 hour, then cooled to about 20° C. and stirred at this temperature for about 1 hour. Hour. The crystalline product was filtered from the mother liquor and washed with deionized water (ca. 100 mL), the wet crystals were stirred with ethyl acetate (1125 mL), and the resulting slurry was heated to reflux and the water was azeotroped. The substantially anhydrous slurry was cooled to about 25°C, the crystals were isolated by filtration and dried in vacuo at about 40°C until all solvent was removed to give the title product, 60.9 g of product, 94%.

The product was characterized by the X-ray powder diffraction pattern described above.

Example 3

Zwitterionic hygroscopic polymorph PII of trofloxacin

Example 1, Part A The title compound (5 g) was slurried with hexane (150 mL). The slurry was heated to reflux and traces of residual water were removed azeotropically. After reflux for 4 hours, the crystal slurry was cooled to about 25°C, separated by filtration and dried under vacuum at about 40°C to constant weight. Product 4.7 g, 94%. The title product was characterized by the X-ray powder diffraction pattern described above.

Example 4

Trofloxacin Zwitterion Pentahydrate

Trofloxacin mesylate (50 g) was stirred with deionized water (250 ml), the crystal slurry was heated to 50° C. and the pH of the slurry was adjusted to about 8.0 by adding saturated sodium bicarbonate solution, and the slurry was The slurry was held at about 50°C for 30 minutes, the column was cooled to about 25°C and stirred at this temperature for 30 minutes. The crystals were isolated by filtration and washed with deionized water (70 ml), the wet crystals were suspended in deionized water (250 ml) and stirred at about 50°C for 1 hour, then cooled to about 20°C and stirred at this temperature for about 1 hour . The crystalline product was filtered from the mother liquor, washed with deionized water (ca. 70 mL), and the wet crystals were air dried at room temperature to constant weight to yield the title product, which contained 17.6% water by analysis. Product 48.4 g, 84%.

The title product was characterized by the X-ray powder diffraction pattern described above.

Claims (20)

1. A zwitterionic crystalline form of trofloxacin of formula I: selected from; a) Non-hygroscopic first polymorph PI exhibiting the following characteristic X-ray powder diffraction pattern number of peaks 1 2 3 4 5 6 7 8 9 2_θ_(°)Cu 6.9 9.8 11.3 12.0 13.9 16.1 16.6 17.1 17.4 d distance 12.7 9.0 7.9 7.4 6.4 5.5 5.4 5.2 5.1 number of peaks 10 11 12 13 14 15 2_θ_(°)Cu 19.7 20.3 21.2 22.8 23.8 26.3 d distance 4.5 4.4 4.2 3.9 3.7 3.4 b) hygroscopic second polymorphic form PII exhibiting the following characteristic X-ray powder diffraction pattern number of peaks 1 2 3 4 5 6 7 8 2_θ_(°)Cu 8.4 9.5 10.2 14.7 16.8 17.9 22.6 26.1 d distance 10.6 9.3 8.7 6.0 5.3 5.0 3.9 3.4 and c) pentahydrate, trofloxacin zwitterion pentahydrate exhibiting the following characteristic X-ray powder diffraction pattern. number of peaks 1 2 3 4 5 6 7 8 9 2_θ_(°)Cu 6.6 8.6 12.7 13.3 15.9 18.6 19.2 20.1 21.0 d distance 13.3 10.3 7.0 6.6 5.5 4.8 4.6 4.4 4.2 number of peaks 10 11 12 13 14 15 16 17 2_θ_(°)Cu 22.6 22.9 23.6 24.9 25.4 25.9 27.7 29.5 d distance 3.9 3.8 3.6 3.5 3.4 3.2 3.0 2. The compound of claim 1 comprising said non-hygroscopic first polymorph PI. 3. The compound of claim 1 comprising said hygroscopic second polymorphic form PII. 4. The compound of claim 1, including said pentahydrate. 5. The compound of claim 1, comprising said metastable form. 6. A method for preparing a compound of formula I, It is selected from the non-hygroscopic polymorph PI, the hygroscopic polymorph PII and its pentahydrate, comprising: A, the step of processing the aqueous suspension of the metastable form of formula I compound: 1) using a non-polar solvent, followed by azeotropic removal of residual water and vacuum drying to form the hygroscopic polymorph PII exhibiting the characteristic X-ray diffraction pattern as recited in claim 1; 2) using a polar solvent, followed by azeotropic removal of residual water and vacuum drying; or 3) air drying the residue with water and at elevated temperature, removing the mother liquor and air drying the residue at room temperature to a constant weight to form the pentahydrate; or B) Treatment of the hygroscopic second polymorph PII with refluxing polar solvent to form the non-hygroscopic first polymorph PI. 7. The method of claim 6, wherein the metastable form of the compound of formula I is prepared by: a) treating the acid salt of trofloxacin with a base at elevated temperature to raise the pH of the mixture to between 7.5 and 8.5; or b) by treating the compound of formula II with amine and/or carboxylic acid respectively as a deprotecting agent wherein A is H or an amine protecting group such as tert-butoxycarbonyl, benzyloxycarbonyl, (C ₁ -C ₆ )alkylcarbonyl and benzyl; and B is H or is selected from benzyl, tert-butyl Carboxylic acid protecting groups for groups and (C ₁ -C ₆ )alkyl groups. 8. The method in step a) of claim 6, wherein the non-polar solvent is hexane. 9. The method in step b) of claim 6, wherein the polar solvent is ethyl acetate. 10. A method of treating a bacterial infection in a mammal, comprising administering to said mammal a therapeutically effective amount of the compound of claim 1. 11. The method of claim 10, wherein said compound is the non-hygroscopic first polymorph PI. 12. The method of claim 10, comprising said compound being the hygroscopic second polymorph PII. 13. The method of claim 10, wherein said compound is trofloxacin zwitterion pentahydrate. 14. A composition for treating bacterial infection in mammals, comprising a therapeutically effective amount of the compound of claim 1 and a pharmaceutically acceptable carrier. 15. The composition of claim 14, wherein said compound is the non-hygroscopic first polymorph PI. 16. The composition of claim 14, wherein said compound is the hygroscopic second polymorph PII. 17. The composition of claim 14, wherein said compound is trofloxacin zwitterion pentahydrate. 18. The compound of claim 14, wherein said composition is a suspension. 19. The method of claim 7, wherein A is H or an amine protecting group such as tert-butoxycarbonyl, benzyloxycarbonyl, ( _C1 - _C6 )alkylcarbonyl and benzyl. 20. The method of claim 7, wherein said compound is B is H and A is selected from benzyl, t-butyl and ( _C1 - _C6 )alkyl.