DESC:
FIELD OF INVENTION:

The present invention relates to novel polymorph of Rifapentine and process for preparation thereof. The present invention further provides a pharmaceutical composition comprising polymorphic form of Rifapentine and one or more of pharmaceutically acceptable carriers, excipients or diluents used in the prevention and/or treatment of active tuberculosis disease or tuberculosis infection.

BACKGROUND OF INVENTION:

Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis, which most commonly affects the lungs. It is transmitted from person to person via droplets from the throat and lungs of people with the active respiratory disease.

About one-third of the world’s population has latent TB, which means people have been infected by tuberculosis bacteria but are not (yet) ill with disease and cannot transmit the disease.

People infected with tuberculosis bacteria have a lifetime risk of falling ill with TB of 10%. However, persons with compromised immune systems, such as people living with HIV, malnutrition or diabetes, or people who use tobacco, have a much higher risk of falling ill. Tuberculosis is a major cause of morbidity in HIV/AIDS patients.

The introduction of shorter treatment regimens for tuberculosis could dramatically reduce disease incidence and associated mortality. Standard treatment with a rifampicin-containing
combination antibiotic regimen for active infection is currently 6 months, whereas the gold standard treatment for latent infection is 9 months of isoniazid. Both treatment options are
orally administered, daily regimens.
Rifapentine in combination with an appropriate daily companion anti-tuberculosis drug (isoniazid, pyrazinamide and ethambutol or streptomycin) is today among the most effective active ingredients against Mycobacterium tuberculosis.

Rifapentine is chemically termed as
3-[[(4-cyclopentyl-1-piperazinyl)imino]methyl]- rifamycin, or
3-[N-(4-Cyclopentyl-1-piperazinyl)formimidoyl] rifamycin, or
(7S,9E,11S,12R,13S,14R,15R,16R,17S,18S,19E,21Z,26E)-26-{[(4-cyclopentylpiperazin-1-yl)amino]methylidene}-2,15,17,29-tetrahydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-6,23,27-trioxo-8,30-dioxa-24-azatetracyclo[23.3.1.14,7.05,28]triaconta-1 (28),2,4,9,19,21,25(29)-heptaen-13-yl acetate and the corresponding chemical structure :

Rifapentine is a rifamycin antimycobacterial indicated for the prevention and/or treatment of pulmonary tuberculosis caused by Mycobacterium tuberculosis in combination with one or more anti-tuberculosis companion drugs

For treatment of pulmonary tuberculosis, the FDA-approved dose of rifapentine is 600 mg twice weekly for 2 months (intensive phase of tuberculosis treatment), with an interval of no less than 3 days (72 hours) between doses, as part of a regimen that includes appropriate daily anti-tuberculosis companion drugs that may include isoniazid, pyrazinamide and ethambutol or streptomycin.

Rifapentine has a potential advantage over rifampin because its long half-life (13 hours compared with 3 hours) could allow for less frequent dosing. It is approved by the United States Food and Drug Administration as a first-line drug for once or twice-weekly dosing in the treatment of tuberculosis. Importantly, recent studies in murine infection models found that much shorter treatment times for tuberculosis could be achieved when oral rifapentine was dosed daily and substituted for rifampicin in the treatment of active infection (3 months) and isoniazid in treating latent infection (2 months).Thus, the substitution of current key antitubercular drugs (rifampicin and isoniazid) with rifapentine might radically alter tuberculosis treatment outcomes.

A disadvantage of rifamycin-containing formulations is their tendency to undergo air oxidation to give a quinone degradation product. It was previously shown that a crystalline dihydrate form of rifampicin did not experience the rapid oxidation seen for its amorphous counterpart. However, because of the differences in chemical structure between the two rifamycins, a crystalline dihydrate form of rifapentine could not be similarly generated by this method (unpublished data). In addition, known crystalline forms of rifapentine are limited to its methanol solvate, which are unsuitable for pharmaceutical use.

Further, inhalation of crystalline Rifapentine overcomes the limitations of oral delivery by significantly enhancing and prolonging the drug concentration in the lungs.

Hence, if efficacious pulmonary levels of rifapentine are to be achieved, there is a need to identify a pure form of crystalline rifapentine that is readily tailored to an inhalable size.

With the growing interest toward the use of crystalline Rifapentine, it could be significant contribution to the art to provide a novel crystalline form of Rifapentine having improved inhalation characteristics, and methods of preparation, pharmaceutical formulations, and methods of use thereof.

OBJECTS OF THE INVENTION:

The object of the present invention is to provide novel crystalline form of Rifapentine.

Another object of the present invention is to provide process for the preparation of novel crystalline form of Rifapentine.

Yet another object of the present invention is to provide pharmaceutical composition comprising a therapeutically effective amount of novel crystalline form of Rifapentine.

Yet another object of the present invention is to provide a process which is simple, economical and suitable for industrial scale-up.

SUMMARY OF THE INVENTION:

The present invention provides novel polymorphic form of Rifapentine.

In one embodiment, the present invention provides crystalline form of Rifapentine hereinafter referred to as Form C2

The crystalline form of Rifapentine may be in a pseudo polymorphic form. Accordingly, pseudo polymorphs are provided that include hydrates and/or solvates.

The crystalline nature of forms according to the present invention is characterized by X-ray powder diffraction.

In another aspect, the present invention relates to process for preparing novel polymorphic form of Rifapentine thereof.

This pure crystalline form proves to be stable and not hygroscopic under usual storage conditions and under usual formulation handlings. This stability throughout the formulation and storage process is of importance for a reliable bioavailability of the administered dose.

In yet another aspect, the invention provides a pharmaceutical composition comprising crystalline Form C2 of Rifapentine, prepared by a process as described above, together with one or more pharmaceutically acceptable excipients. Such excipients are well known to those skilled in the art.

Suitably, the pharmaceutical composition is in the form of a tablets, film-coated tablets, sugar coated tablets, capsules, hard gelatin capsules, soft gelatin capsules, troches, and the like suitable for oral delivery.

In yet another aspect, the invention provides the use of crystalline Form C2 of Rifapentine, prepared by a process as described above in medicine.

In yet another aspect, the invention provides crystalline Form C2 of Rifapentine, prepared by a process as described above for use in the prevention and/or treatment of pulmonary tuberculosis caused by Mycobacterium tuberculosis in combination with one or more anti-tuberculosis companion drugs.

In an embodiment, the appropriate daily companion anti-tuberculosis drugs are chosen among isoniazid, pyrazinamide and ethambutol or streptomycin.

In yet another aspect, the invention provides the use of crystalline Form C2 of Rifapentine
as described above for use in the manufacture of a medicament for prevention and/or treatment of pulmonary tuberculosis caused by Mycobacterium tuberculosis.
In yet another aspect, the invention provides a method of prevention and/or treatment of pulmonary tuberculosis caused by Mycobacterium tuberculosis comprising administering to a patient in need thereof a therapeutically effective amount of crystalline Form C2 of Rifapentine as described above

In yet another aspect, the invention provides a pharmaceutical composition comprising crystalline Form C2 of Rifapentine prepared by a process as described above, for use in the prevention and/or treatment of active tuberculosis disease or tuberculosis infection in HIV/ AIDS infected patients treated with an antiretroviral combination.

In yet another aspect, the invention provides crystalline Form C2 of Rifapentine, prepared by a process as described above for use in the prevention and/or treatment of active tuberculosis disease or tuberculosis infection in HIV/ AIDS infected patients treated with an antiretroviral combination.

In yet another aspect, the invention provides the use of crystalline Form C2 of Rifapentine
as described above for use in the manufacture of a medicament for prevention and/or treatment of active tuberculosis disease or tuberculosis infection in HIV/ AIDS infected patients treated with an antiretroviral combination.

In yet another aspect, the invention provides a method of prevention and/or treatment of active tuberculosis disease or tuberculosis infection in HIV/ AIDS infcted patients treated with an antiretroviral combination, comprising administering to a patient in need thereof a therapeutically effective amount of crystalline Form C2 of Rifapentine as described above

In an embodiment, the antiretroviral combination is a combination of efavirenz, emtricitabine and tenofovir disoproxil fumarate.

In an embodiment, the antiretroviral combination is a combination of 600 mg efavirenz, 300 mg of emtricitabine and 200 mg tenofovir disoproxil fumarate.
Rifapentine and one or more appropriate daily companion anti-tuberculosis drugs for use in the treatment of active tuberculosis disease or tuberculosis infection in HIV/AIDS infected patients treated with an antiretroviral combination, wherein the appropriate daily companion anti-tuberculosis drugs are chosen among isoniazid, pyrazinamide and ethambutol or streptomycin.

Brief Description of the Drawings

Figure 1 depicts X-Ray Powder Diffraction (XRPP) pattern of crystalline Form C2 of Rifapentine.

Figure 2 depicts Differential Scanning Calorimetry (DSC) of crystalline Form C2 of Rifapentine.

Figure 3 depicts Infrared Spectrum (IR) of crystalline Form C2 of Rifapentine.

Figure 4 depicts Thermogravimetric analysis (TGA) of crystalline Form C2 of Rifapentine.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Unless defined otherwise, 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, and are consistent with:

As used herein, the term "PXRD" refers to powder X-ray diffraction, the term "IR" refers to infrared, the term "NMR" refers to nuclear magnetic resonance, the term "TGA" refers to thermogravimetric analysis, the term "DSC" refers to differential scanning calorimetry and the term "DVC" refers to dynamic vapour sorption isotherm.

As used herein, the term "substantially the same X-ray powder diffraction pattern" is understood to mean that those X-ray powder diffraction patterns having diffraction peaks with 2? values within ± 0.2° of the diffraction pattern referred to herein are within the scope of the referred to diffraction pattern.

As polymorphic forms are reliably characterized by peak positions in the X-ray diffractogram, the polymorphs of the present invention have been characterized by powder X-ray diffraction spectroscopy which produces a fingerprint of the crystalline form and is able to distinguish it from all other crystalline and amorphous forms of Rifapentine.

All the powder diffraction patterns were measured on a PANalytical X’Pert3 X-ray powder diffractometer with a copper-K-a radiation source.

The novel polymorphs of the present invention may be isolated in pseudo polymorphic form as a solvate optionally in hydrated form, or as a non-hydrated solvate.

The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

Thus, in one aspect, the present invention provides the crystalline Rifapentine which is herein and in the claims designated as “Form C2”, which has good flow characteristics.

In an embodiment, crystalline Form C2 of Rifapentine. referred in this specification is anhydrous.

In one embodiment, the crystalline Form C2 of Rifapentine is characterized by an X-ray powder diffraction pattern comprising the following 2? values measured using CuKa, radiation.

In an embodiment, the crystalline Form C2 of Rifapentine has an XRD pattern with characteristics peaks at 18.24, 19.5, 23.77, and 26.59 ± 0.2°2?.

The XRPD diffractogram may comprise further peaks at 7.96 , 9.03 , 9.77,11.98, 15.86, 21.33 and 22.85 ± 0.2 °2?. The XRPD diffractogram may be as depicted in Figure 1.

In an embodiment, the crystalline Form C2 of Rifapentine has an XRPD pattern with those peaks at °2? values ± 0.2 °2? as depicted in Table 1.

Table 1: Table of values for the XRPD pattern depicted in Figure 1

Peak value (°2?) Relative Intensity [%]
7.96 55.8
9.03 41.64
9.77 39.2
11.98 98.93
13.83 33.11
15.86 20.21
18.24 19.78
19.5 100
21.33 65.78
22.85 27.08
23.77 24.45
26.59 19.08

Crystalline Form C2 of Rifapentine may also be characterized as having a DSC spectrum. The DSC plot for the sample shows one endotherm with an onset at 180.19±5°C and a peak maximum at 190±5°C.
In an embodiment, crystalline Form C2 of Rifapentine is characterized by having a DSC spectrum as shown in Figure 2.

Infrared (FT-IR) spectra were obtained in a KBr disk using a Perkin Elmer FT-IR spectrophotometer Spectrum 1000 at resolution 4 cm-1. The characteristic absorption bands are expressed in cm-1.

In an embodiment, crystalline Form C2 of Rifapentine of the present invention is characterized by having characteristic IR spectra peaks at about 3345 cm¬-1, 3441 cm¬-1, 3303 cm¬-1, 1702 cm¬-1, 1664 cm¬-1,1615 cm¬-1 and 1234 cm¬-1.

In another embodiment, crystalline Form C2 of Rifapentine is characterized by having an Infrared spectrum (IR) profile as shown in Figure 3.

In another embodiment, crystalline Form C2 of Rifapentine is characterized by having a thermogravimetric analysis (TGA) profile as shown in Figure 4.

Those skilled in the art would recognize that crystalline Form C2 of Rifapentine may be further characterized by other methods including, but not limited to solid state NMR, intrinsic dissolution and Raman spectroscopy.

The novel crystalline Form C2 of Rifapentine obtained according to the present invention is substantially free from other crystal and non-crystal forms of Rifapentine. “Substantially free” from other forms of Rifapentine shall be understood to mean that the polymorphs of Rifapentine contain less than 10%, preferably less than 5%, of any other forms of Rifapentine and less than 1% of other impurities, water or solvates. Thus, the crystalline Form C2 of Rifapentine prepared according to the present invention contains less than 11% total impurities, preferably less than 6% total impurities. In a particularly preferred embodiment, the crystalline Form C2 of Rifapentine prepared according to the present invention contains less than 1% total impurities.

According to another aspect of the present invention, there is provided a process for preparing crystalline Form C2 of Rifapentine, the process comprising

a) mixing Rifapentine in a suitable organic solvent or mixture of organic solvents;
b) stirring for at least 8-10 hours at -5 to 10°C;
c) isolating the precipitated crystalline Form C2; and
d) drying under reduced pressure at 50-60°C, preferably at 40-50°C for at least 3-5 hours.

In an alternative embodiment, crystalline Form C2 of Rifapentine can also be generated by semi continuous crystallization in solvent or mixture of solvent. In one example, the crystalline Form C2 of Rifapentine seed solids are charged to a solvent to form the seed slurry. Then, Rifapentine is simultaneously charged to the seed slurry, while maintaining the appropriate solvent composition.

In an embodiment Rifapentine base may be in any polymorphic form or in a mixture of any polymorphic forms. The starting material Rifapentine can be obtained by the process of the present invention or any methods known in the art, such as the one described in PCT application WO 92/00302 which is incorporated herein by reference.

In an embodiment, organic solvents are selected from but not limited to the group comprising of C1 to C5 alcohols, nitriles, C1 to C6 halogenated hydrocarbons, C6 to Cl4 aromatic hydrocarbons, C2 to C7 esters, C4 to C7 ethers, cyclic ethers, aromatic ethers or suitable mixtures of these solvents.

Preferably, organic solvents are selected from C1 to C5 alcohols such as methanol, ethanol, isopropanol, t-butanol and the like. More preferably organic solvent is ethanol.

In an embodiment, removal of solvent include but not limited to evaporation, flash evaporation, simple evaporation, rotational drying, spray drying, agitated thin-film drying, Rotary vacuum paddle dryer, agitated nutsche filter drying, pressure nutsche filter drying, freeze -drying or any other suitable technique known in the art. In an embodiment solvent may be removed at normal pressure or under reduced pressure.

In an embodiment, isolation include but not limited to filtration by gravity or suction, centrifugation, decantation, and any other known techniques in the art.

In an embodiment, drying can be carried out in a tray dryer, vacuum oven, air oven, cone vacuum dryer, rotary vacuum dryer, fluidized bed dryer, spin flash dryer, flash dryer, or the like.

The invention is further described by reference to the following examples, which set forth in detail certain aspects and embodiments of the preparation of compounds and compositions of the present invention. It will be apparent to those skilled in the art, that many modifications, both to materials and methods, can be practiced without departing from the purpose and intent of this invention. The examples that follow are not intended to limit the scope of the invention as described herein above or as claimed below.

Examples

Example 1
Preparation of 3-Formyl Rifamycin SV
a. Preparation of t-Butylazomethaine
To a chilled solution of formaldehyde solution ( (37% in water, 46.5 ml, 0.57 moles) was added tert-butyl amine (68 ml, 0.65 moles ) 0-5°C. The reaction mass was stirred for 2 hours at 5-10°C. The pH of the reaction mass was maintained at 9-10. The organic layer was separated and dried over anhydrous sodium sulfate.
Yield : 37-38 g
b. Preparation of 3-Formyl Rifamycin SV
Rifamycin S (100 g, 0.14 moles) was dissolved in THF (500 ml) at 20-30°C. Charged t-Butylazomethaine (37.6 g) obtained in step a, at 20-30°C and stirred for 15 min. Added tert-butyl amine (16.5 ml, 0.15 moles ) at 20-30°C and stirred for 15 min. Added Manganese dioxide (56.0 gm, 0.64 moles) at 20-30°C and stirred for 15 min. The temperature of the reaction mass was raised to 45-50°C and stirred for 24 hours. After completion of reaction, the reaction mass was cooled to 5-10°C. The reaction mass was filtered through hyflo bed and washed bed with 100 ml THF. To the clear filtrate was added water (250 ml). The reaction mass was cooled to 0-5°. The pH of the reaction mass was adjusted to 2-5 using 8% sulfuric acid solution (16 ml of sulfuric acid in 184 ml of water). Added ascorbic acid solution ( dissolved 50 g of ascorbic acid into 250 ml of water) into the reaction mass below 10°C. The temperature of the reaction mass was raised to 25-30°C and stirred for 16 hours. After completion of reaction, the reaction mass was filtered, solids were washed with 100 ml of water and dried under vacuum at 40-45°C till LOD was less than 10%.
Yield: 70 g

Example 2
Preparation of Rifapentine
Dissolved 1-Amino-4-Cyclopentyl Piperazine (26 g, 0.092 moles) in methanol (300 ml) at 25-30°C under nitrogen. Charged 3-Formyl Rifamycin SV (100 g, 0.084 moles) below 30°C. Stirred for 1 hour at 25-30°C. After completion of reaction, the reaction mass was filtered and washed with 50 ml of methanol. The clear filtrate was charged slowly into water (700 ml) below 30°C. The reaction mass was stirred further for 1 hour at 25-30°C. The solids were isolated by filtration, washed with 100 ml water and dried under vacuum at 40-45°C till water content was less than 3.0%
Yield :100 g

Example 3
Preparation of crystalline Form C2 of Rifapentine
To a cooled solution of ethanol (denatured with 0.5% Acetone) (400 ml) was charged Rifapentine (100 g) slowly in lots, maintaining temperature between 15-20°C. The reaction mass was further stirred for 5 hours at 25°C. The reaction mass was chilled to -5°C to 0°C and further stirred for 5 hours.
The solids were isolated by filtration, washed with 25 ml of chilled Ethanol (denatured with 0.5% Acetone) and dried under vacuum at 40-45°C till water content was less than 1.25%.
Yield: 80-85 gm
The sample was subsequently analysed by XRPD, DSC, IR and TGA and showed the spectrum of Crystalline Form C2, which is shown in Figures 1-4.

Example 4
Preparation of crystalline Form C2 of Rifapentine
To a cooled solution of ethanol ( denatured with 0.5% Acetone) (240 ml) was seeded with Rifapentine Form C2 and stirred for 10-15 min at 15-20°C. Charged Rifapentine ( 60 g ) slowly in lots maintaining temperature between 15-20°C. The reaction mass was further stirred for 3-4 hours at 18-25°C. The reaction mass was chilled to -5°C to 0°C and further stirred for 4 hours at -5°C to 0°C .
The solids were isolated by filtration, washed with 15 ml of chilled Ethanol (denatured with 0.5% Acetone) and dried under vacuum at 40-45°C till water content was less than 1.25%.
Yield: 54 gm
The sample was subsequently analysed by XRPD, DSC, IR and TGA and showed the spectrum of Crystalline Form C2, which is shown in Figures 1-4.

Example 5
Preparation of crystalline Form C2 of Rifapentine
To a cooled solution of ethanol ( denatured with 0.5% Acetone) (200 ml) was charged amorphous Rifapentine ( 50 g ) slowly in lots maintaining temperature between 15-20°C. The reaction mass was further stirred for 5 hours at 25°C. The reaction mass was further chilled to -5°C to 0°C and further stirred for 5 hours.
The solids were isolated by filtration, washed with 15 ml of chilled Ethanol (denatured with 0.5% Acetone) and dried under vacuum at 40-45°C till water content was less than 1.25%.
Yield: 40-45 gm
The sample was subsequently analysed by XRPD, DSC, IR and TGA and showed the spectrum of Crystalline Form C2, which is shown in Figures 1-4.
,CLAIMS:
1. Crystalline Form C2 of Rifapentine.
2. The Crystalline Form C2 of Rifapentine of claim 1, characterized by XRPD diffractogram with characteristics peaks at 18.24, 19.5, 23.77, and 26.59 ± 0.2°2?.
3. The Crystalline Form C2 of Rifapentine of claim 2, further characterized by XRPD diffractogram with characteristics peaks at 7.96 , 9.03 , 9.77,11.98, 15.86, 21.33 and 22.85 ± 0.2 °2?.
4. The Crystalline Form C2 of Rifapentine of claims 2 and 3, characterized by XRPD diffractogram as depicted in Figure 1.
5. The Crystalline Form C2 of Rifapentine of claim 1, characterized by a DSC spectrum. having an endothermic peak with an onset at 180.19±5°C and a peak maximum at 190±5°C.
6. The Crystalline Form C2 of Rifapentine of claim 5, further characterized by having a DSC spectrum as shown in Figure 2.
7. The Crystalline Form C2 of Rifapentine of claim 1, characterized by an IR spectrum having characteristic peaks at about 3345 cm¬-1, 3441 cm¬-1, 3303 cm¬-1, 1702 cm¬-1, 1664 cm¬-1,1615 cm¬-1 and 1234 cm¬-1.
8. The Crystalline Form C2 of Rifapentine of claim 7, further characterized by having an Infrared Spectrum (IR) as shown in Figure 3.
9. The Crystalline Form C2 of Rifapentine of claim 1, characterized by having a Thermogravimetric analysis (TGA) as shown in Figure 4.
10. A process for preparing crystalline Form C2 of Rifapentine of claim 1, the process comprising the steps of:
a) mixing Rifapentine in a suitable organic solvent or mixture of organic solvents;
b) stirring for at least 8-10 hours at -5 to 10°C;
c) isolating the precipitated crystalline Form C2; and
d) drying under reduced pressure at 50-60°C, preferably at 40-50°C for at least 3-5 hours.
11. The Crystalline Form C2 of Rifapentine of claim 10, further comprising the step of:
a1) seeding the organic solvent or mixture of organic solvents with Form C2 prior to mixing with Rifapentine and allowing the solution to stir until a slurry is formed.
12. The Crystalline Form C2 of Rifapentine of claims 10 and 11, wherein the organic solvents are selected from the group comprising of C1 to C5 alcohols, nitriles, C1 to C6 halogenated hydrocarbons, C6 to Cl4 aromatic hydrocarbons, C2 to C7 esters, C4 to C7 ethers, cyclic ethers, aromatic ethers or suitable mixtures of these solvents.
13. A pharmaceutical composition comprising the Crystalline Form C2 of Rifapentine according to claim 1 and a pharmaceutically acceptable excipient.
14. A method of prevention and/or treatment of pulmonary tuberculosis caused by Mycobacterium tuberculosis comprising administering to a patient in need thereof a therapeutically effective amount of crystalline Form C2 of Rifapentine according to claim 1.