Claims:We claim:

1) An anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate characterized by powder X-ray diffraction pattern with peaks at about 8.05, 12.70, 14.45, 16.10, 16.35 & 18.90 ± 0.2 degrees 2-theta angles.
2) The anhydrous form of S-(+) Hydroxychloroquine sulfate as claimed in claim-1, wherein, the anhydrous crystalline form is further characterized by differential scanning calorimetry (DSC) thermogram having two endotherm characteristic peaks- at about 132 to 140°C and at about 245 to 249°C.
3) The anhydrous form of S-(+) Hydroxychloroquine sulfate as claimed in claim-1, wherein, the anhydrous crystalline form is characterized by presence of moisture content in the range of 0.1 % to 2.5 %.
4) A process for preparing anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate comprising heating S-(+) Hydroxychloroquine sulfate hydrate at 180°C – 240°C.
5) The process as claimed in claim-4, wherein, the heating is carried out in the range of at about 180°C – 240°C atmospherically or under vacuum.
6) The process as claimed in claim-5, wherein, the heating at about 180°C – 200°C is carried out atmospherically.
7) The process as claimed in claim-5, wherein, the heating is carried out for a period of 1 hr to less than six hours.
8) A pharmaceutical composition or dosage form comprising anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate and at least one pharmaceutical excipient.
, Description:Field of the invention:
The present invention relates to a novel anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate. The present invention further relates to process for preparing anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate and its characterization.

Background of Invention:
S-(+) Hydroxychloroquine sulfate, chemically known as (S)-(+)-2-[[4-[(7-chloro-4-quinolinyl)amino]pentyl]ethylamino]ethanol which is useful in the treatment of acute attacks and suppression of malaria due to Plasmodium vivax, Plasmodium malariae, Plasmodium ovale and susceptible strains of Plasmodium falciparum, systemic and discoid lupus erythematosus and rheumatoid arthritis. S-(+) Hydroxychloroquine sulfate is having following chemical formula.

S-(+) Hydroxychloroquine sulfate is first reported in US5314894 and its racemic form is reported first in US2546658.

It is well known that a compound can often exist in different crystalline forms, which is called polymorphism. Generally speaking, different crystalline forms of the same drug can have different physical properties and chemical stabilities. It is quite important to use a drug having a definite crystalline form as a bio-active component during the manufacture of pharmaceutical preparations, which will not only exert its therapeutical effects, but also effectively reduce its toxicity and side effects.
It is well known that a crystalline form of a substance is identified with a powder X-ray diffraction spectrum (PXRD), a differential scanning calorimetry (DSC), an infrared absorption spectrum (IR) & thermogravimetric analysis (TGA).

The US5314894 patent reported preparation of S-(+) hydroxychloroquine sulfate by treating (+) Hydroxychloroquine with one equivalent of one molar sulfuric acid in methyl alcohol. After completion of reaction, the alcohol was evaporated to obtain sticky oily mass which was dissolved in methanol followed by addition of acetone to obtain crystalline sulfate salt. The crystalline salt was dried at 50°C (0.001 torr) for 24 hours to obtain off -white S-(+) hydroxychloroquine sulfate having m.p 235-238°C (dec). However, this patent failed to disclose any solid state properties of S-(+) hydroxychloroquine sulfate. When the product was prepared under similar reported conditions, it has been found that the process results in crystalline S-(+) hydroxychloroquine sulfate in monohydrate form. The XRPD pattern of crystalline S-(+) Hydroxychloroquine sulfate monohydrate is shown in figure 1-2. DSC of the monohydrate of the crystalline S-(+) hydroxychloroquine sulfate found to be having one endotherm followed by one exotherm peak which is followed by another endotherm, as shown in figure 3. First endotherm is ranging broadly from at about 57 to 155°C. The exotherm is ranging from at about 180-190°C and another endotherm peak is ranging from at about 244-249°C. Water content in the monohydrate form as measured by Thermogravimetry analysis found to be ranging from 4-5.3%, as shown in figure 4.

Therefore, the present inventors have endeavored to develop another crystalline form which is anhydrous crystalline form of the S-(+) Hydroxychloroquine sulfate.

Summary of Invention:
Accordingly in one aspect, the present invention provides a novel anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate. More particularly, the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate is characterized by powder X-ray diffraction pattern with peaks at about 8.05, 12.70, 14.45, 16.10, 16.35 & 18.90 ± 0.2 degrees 2-theta angles. The anhydrous crystalline form is also characterized by differential scanning calorimetry (DSC) thermogram having two endotherm characteristic peaks. First peak is having an endotherm range at about 132 to 142°C and other peak is having endotherm range at about 245 to 249°C.

According to second aspect, the present invention provides process for preparation of the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate comprising heating S-(+) Hydroxychloroquine sulfate hydrate at about 180°C – 240°C.

In a preferred embodiment of the invention, the present invention provides process for preparation of the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate comprising heating S-(+) Hydroxychloroquine sulfate hydrate at about 180°C – 200°C under vacuum or at atmospheric pressure.

Brief description of the accompanying drawings:
Figure-1-2 represents XRPD pattern of crystalline S-(+) Hydroxychloroquine sulfate monohydrate.
Figure-3 represents Differential Scanning Calorimeter thermogram of crystalline S-(+) Hydroxychloroquine sulfate monohydrate.
Figure -4 represents Thermo-Gravimetric Analysis (TGA) thermogram of crystalline S-(+) Hydroxychloroquine sulfate monohydrate.
Figure-5-6 represents XRPD pattern of anhydrous crystalline S-(+) Hydroxychloroquine sulfate.
Figure-7 represents Differential Scanning Calorimeter thermogram of anhydrous crystalline S-(+) Hydroxychloroquine sulfate.
Figure -8 represents Thermo-Gravimetric Analysis (TGA) thermogram of anhydrous crystalline S-(+) Hydroxychloroquine sulfate.

Description of Invention:
Unless specified otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods and materials are described. To describe the invention, certain terms are defined herein specifically as follows.
Unless stated to the contrary, any of the words "including," "includes," "comprising," and "comprises" mean "including without limitation" and shall not be construed to limit any general statement that it follows to the specific or similar items or matters immediately following it.
The term “anhydrous” as used herein with reference to crystalline S-(+) Hydroxychloroquine sulfate denotes moisture content thereof of less than about 2.5% by weight.
The term “monohydrate” as used herein with reference to crystalline S-(+) Hydroxychloroquine sulfate denotes moisture content thereof at about 4-5.3% by weight.
The term “hydrate” as used herein with reference to crystalline S-(+) Hydroxychloroquine sulfate hydrate denotes moisture content thereof more than 4.1 %.

The invention provides a novel form of anhydrous crystalline S-(+) Hydroxychloroquine sulfate and process for preparation of the novel form. The various aspects of the invention are described in detail with the preferred embodiments/conditions hereafter.

Accordingly, in one aspect, the present invention provides a novel anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate. the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate is characterized by powder X-ray diffraction pattern with peaks at about 8.05, 12.70, 14.45, 16.10, 16.35 & 18.90 ± 0.2 degrees 2-theta angles. XRPD of the anhydrous form is depicted in Figure- 5-6. The anhydrous crystalline form is also characterized by differential scanning calorimetry (DSC) thermogram having two endotherm characteristic peaks. First peak is having an endotherm range at about 132 to 142°C and other peak is having endotherm range at about 245 to 249°C. Surprisingly it is found that the endotherm at 132-142°C is emerged additionally in the new anhydrous form. The DSC thermogram of the anhydrous form is depicted in Figure-7. Water content in the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate may be present in the range of at about 0.1 % to 2.5 % as measured by thermo gravimetry analysis. The thermogram of TGA is depicted in Figure- 8.

According to second aspect, the present invention provides process for preparation of the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate comprising heating S-(+) Hydroxychloroquine sulfate hydrate in the range of 180°C – 240°C .

In a preferred embodiment, present invention provides a process for preparation of the anhydrous crystalline form of S-(+) Hydroxychloroquine sulfate comprising heating S-(+) Hydroxychloroquine sulfate hydrate in the range of 180°C – 220°C at atmospheric pressure or under vacuum. Drying may be done for a period of 1 hr to less than six hours atmospherically. Vacuum may be applied during drying to speed up the drying process.

The starting material, S-(+) Hydroxychloroquine sulfate hydrate, may be prepared by the known procedure, as per the disclosures of US5314894. Racemic 2-[(4-aminopentyl)ethylamino]ethanol of Formula-I is reacted with (S)-(+)-mandelic acid in i-propanol solvent to obtain corresponding diastereomer of mandelic acid - (S)-(+)-2-[(4-aminopentyl)ethylamino]ethanol salt of Formula-II. The reaction mass is filtered to separate the salt and mother liquor. The salt is taken in methyl tetrabutyl ether (MTBE) and neutralized with dilute NaOH to liberate the S-2-[(4-Aminopentyl)ethylamino]ethanol of Formula-III. The mother liquor is subjected for distillation of i-propanol, neutralized with aqueous NaOH and then extracted with methyl t-butyl ether to recover 2-[(4-aminopentyl)ethylamino]ethanol enriched with R enantiomer.

The S-2-[(4-aminopentyl)ethylamino]ethanol is condensed with 4,7-dichloroquine (4,7-DCQ) in water in presence of sodium carbonate and iodide catalyst such as potassium iodide in autoclave under N2 pressure. The reaction is conducted at about 120°C for a period of about 60 hours. After completion of reaction, the product, in oily form, is separated and washed with water followed by toluene. The oily S-(+) Hydroxychloroquine product of Formula-IV is dissolved in methanol treated with charcoal then added concentrated sulfuric acid. Then distilled the methanol and added ethanol. The reaction mass is refluxed further, cooled and filtered to obtain S-(+) Hydroxychloroquine sulfate hydrate. The reaction is depicted in scheme-1.

Scheme-1:

S-(+) Hydroxychloroquine sulfate hydrate thus obtained is dried at 200°C for 2 hours to obtain anhydrous S-(+)hydroxychloroquine sulfate.

Further, the recovered 2-[(4-aminopentyl)ethylamino]ethanol enriched with R-enantiomer is subjected for resolution in similar fashion as mentioned above and isolated R-2-[(4-aminopentyl)ethylamino]ethanol. Further, the racemic mixture of 2-[(4-aminopentyl)ethylamino]ethanol is recovered from the filtrate.

The anhydrous S-(+) Hydroxychloroquine sulfate obtained by the present invention, may be formulated into a suitable dosage form such as tablets, capsules, powders, sachets, lozenges, syrups and suspensions etc., by combining with one or more pharmaceutically acceptable excipients using known techniques. The dosage form may include a suitable amount of the active ingredient and other pharmaceutical agents. The dosage forms prepared by the process of the present invention may be administered to a mammal in need, for the treatment of malaria, lupus erythematosus or rheumatoid arthritis.

The following examples are presented to further explain the invention with experimental conditions, which are purely illustrative and are not intended to limit the scope of the claimed invention.

Example- 1:
(R,S)-2-[(4-aminopentyl)ethylamino]ethanol (600 g) was stirred in i-propanol (2700 mL) and then S(+)- Mandelic acid was added to reaction mass and maintained for 22 hours at 30°C. The reaction mass was then filtered and slurried in i-propanol (2400 mL) twice, filtered and washed with 100 mL of i-propanol. The wet solid (533.7gm) was stirred in 35% sodium hydroxide solution (prepared by dissolving 378.3 gm of NaOH in 1000 mL of water) and extracted with 1200 mL of methyl t-butyl ether three times. Combined methyl t-butyl ether layers were concentrated to get 190 gm of S-2-[(4-aminopentyl)ethylamino]ethanol as oil. Aqueous layer was subjected for recovery of S(+)- Mandelic acid.

Example- 2:
The mother liquor from Example- 1 containing i-propanol was distilled atmospherically and the resulting residue was stirred in 35% sodium hydroxide solution and extracted with methyl t-butyl ether. Methyl t-butyl ether was then distilled atmospherically at 58°C to get 2-[(4-aminopentyl)ethylamino]ethanol (415 g) enriched with R enantiomer.

Example- 3:
The aqueous layer obtained from Example- 1 & 2 was cooled to 0-5°C and acidified with concentrated hydrochloric acid up to pH 1.0 and filtered to yield S(+)- Mandelic acid (220 g).

Example- 4:
In an autoclave, charged S-2-[(4-aminopentyl)ethylamino]ethanol (98.56 g), 4,7- dichloroquinoline (100 g), potassium iodide (4 g), sodium carbonate (28.36 g) & water (26 ml), reaction mass was heated to 120°C under nitrogen pressure (2 kg/cm2) and maintained for 60 hours at 120°C & 2 kg/cm2 pressure till completion of reaction. The reaction was then cooled to 70-75°C and separated oily layer from aqueous layer. Organic layer was washed with water (450 ml) thrice. Then the organic layer was washed with toluene (200 ml) at 70-75°C four times. The obtained oily S-(+)hydroxychloroquine is taken for next reaction.

Example- 5:
S-(+)hydroxychloroquine from Example- 4 was charcoalised in methanol (300 ml) and then added conc. sulfuric acid (45gm) dissolved in 300 mL methanol till 5.6- 5.9 pH is reached. The reaction mass was distilled under vacuum and stripped with water (10 ml). The reaction mass was then stripped with ethanol. Then added ethanol (1000 ml) and refluxed for 2-3 hours, cooled to RT and filtered to yield S-(+)hydroxychloroquine sulfate. Dried the solids at 45-50°C under vacuum (10-15 torr) to yield 145 gm of S-(+)hydroxychloroquine sulfate. This was further dried at 200°C for 2 hours to obtain anhydrous S-(+)hydroxychloroquine sulfate. XRD values are mentioned in the figures 5- 6. DSC values as reported in figure -7. Thermo-Gravimetric Analysis (TGA) is reported in figure-8.

Example- 6:
410 gm of (R,S)-2-[(4-aminopentyl)ethylamino]ethanol (415 g) enriched with R enantiomer obtained in example-2 was reacted with R-Mandelic acid (179gm) in i-propanol solvent similarly as mentioned in example-2 and 3 and obtained 124 gm of R-2-[(4-aminopentyl)ethylamino]ethanol as oil.

From the filtrate, 250 gm of racemic (R,S)-2-[(4-aminopentyl)ethylamino]ethanol was recovered