Salts of N-[6-cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide

Preparation of the Diphosphate Salt

To a 250 mL, three-necked reaction flask 7.0 g (0.0144 mole) of 2-methyl-4′-trifluoromethoxy-biphenyl-3-carboxylic acid [6-(cis-2,6-dimethyl-morpholin-4-yl)-pyridin-3-yl]-amide free base and acetonitrile (178.5 mL, HPLC grade) was added under nitrogen. The suspension was heated to 58° C. under nitrogen over 20 minutes to obtain a clear solution. To the reaction solution 3.403 g of 85% phosphoric acid in water (2 equiv) was added over 18 minutes. Within 5 minutes of the phosphoric acid addition, N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide di-phosphate precipitates out. The white slurry was stirred and cooled to room temp over 100 minutes. The slurry was then cooled to 0±5° C. over 5 minutes and stirred for 1 hour. The mixture was filtered under suction and solid was washed with acetonitrile (3×9.4 mL). The drug substance was dried under vacuum at 50° C. for 16 hours to obtain 9.63 g of the phosphate salt (yield: 98%).

Preparation for the Monosulfate Salt

To a 100 mL, three-necked reaction flask was charged 3.0 g (6.18 mmole) of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide free base and acetonitrile (35 mL, HPLC grade) under nitrogen. The suspension was heated to 50° C. under nitrogen over 30 minutes to obtain a clear solution. To the mixture was added a 1.5 mL of 6 M sulfuric acid (1.5 equiv) over 10 minutes. The mixture was stirred at 50° C. for 3 hours and allowed to cool to 25° C. over 25 minutes. Within 5 minutes the solids came out. The slurry was stirred at 25° C. for 16 hours. The mixture was filtered under suction and solid was washed with acetonitrile (10 mL). The drug substance was dried under vacuum at 55° C. for 16 hours to obtain 3.0 g of the sulfate salt (yield: 83%).

Preparation for the Monohydrochloride Salt

To a 100 mL, three-necked reaction flask was charged 3.0 g (6.18 mmole) of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide free base and acetone (25 mL, HPLC grade) under nitrogen. The suspension was stirred at 25° C. under nitrogen for 30 minutes to obtain a clear solution. To the mixture was added a 1.5 mL of 6 M hydrochloric acid (1.5 equiv) over 10 minutes. Within 5 minutes the solids came out. The slurry was stirred at 25° C. for 16 hours. The mixture was filtered under suction and solid was washed with acetone (10 mL). The drug substance was dried under vacuum at 55° C. for 16 hours to obtain 3.0 g of the hydrogen chloride salt (yield: 93%).

Table 1 below shows stability measured by degradation products (or assay) and appearance color. DPs are analyzed by HPLC (method see Table 3). They are calculated as area-% products. Compositions of the mixtures in mass % are as follows. Mixture 1: Lactose 200 mesh/maize starch modified 1500 LM/Aerosil 200/Magnesiumstearate 78.5:20:0.5:1 (m/m/m/m). Mixture 2: Mannitol/Avicel PH 102/Cutina HR (57:38:5) (m/m/m).

Table 2 below shows chemical and physico-chemical characteristics.

Table 3 below shows morphic properties.

Rat TK data of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide diphosphate dosed as a suspension, with a 10-fold increase in dose, showed a 3.1-fold increase in exposure from 10 to 100 mpk. The inter-subject exposure is slightly variable, especially at high dose (100 mpk). See Table 4.

A suspension formulation of the free form and the diphosphate salt of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide are dosed to rat at 3 mpk and 2.1 mpk, respectively. It was found that the disphosphate salt provided a large increase in exposure (16-fold increase) compared to the free form as outline in Table 5.

Details about Methodology, Instruments and Standards Used in Examples 4-5

1 pH Value

The pH was determined by transferring approximately 10 mg of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy) [1,1′-biphenyl]-3-carboxamide salt to a 20 mL vial and adding 10 mL of the corresponding buffer or water. The solutions were stirred continuously as the pH was measured.

2 Determination of Approximate Solubility

Excess salts were equilibrated in solvents for 1 day at 25±0.5° C. Slurries were filtered and the filtrate saved for HPLC solubility determination.

3 Hygroscopicity

Sorption/desorption isotherms: Instrument, Surface Measurement System DVS-1 temperature at 25±0.5° C.

4 Polymorphism Behavior

Slurries of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide salts were stirred at high speed for 24 hours at 25±0.5° C. The slurries were filtered and the solids collected for XRPD analyses.

5 HPLC Method

Column: Symmetry C18, 3.5 micrometer particle diameter, 4.6×75 mm (Waters)

Column temperature: 35 degrees

Flow rate: 1 mL/min

Mobile phase: A=0.1% TFA in water, and B=acetonitrile

Gradient table shown below in Table 6:

Stability Sample Preparation for HPLC Analysis:

For phosphate in pH 1 buffer solution, acetonitrile was added to dilute the 0.2% slurry to 0.1% clear solution. For phosphate in the rest of buffer solutions, tetrahydrofuran was added to dilute the 0.2% slurry to 0.1% clear solution. For salts in water, acetonitrile was added to dilute the 0.2% slurry to 0.1% clear solution. For salts in methanol, acetonitrile or acetonitrile/water (50:50, v/v), the corresponding solvent or solvent mixture was added to dilute the 0.2% slurry to 0.1% clear solution. For salts in 0.5% CMC, HPMC cellulose 4000 0.5%, or Tween 80, 0.8%, tetrahydrofuran and water were added to dilute the 2% slurry to 0.1% clear solution and to reach tetrahydrofuran/water 50:50 (v/v). For bulk stability samples (including the samples in excipient mixtures), acetonitrile/water (80:20, v/v) was added to make 0.1% clear solution.

The sulfate salt and diphosphate salt of N-[6-(cis-2,6-dimethylmorpholin-4-yl)pyridine-3-yl]-2-methyl-4′-(trifluoromethoxy)[1,1′-biphenyl]-3-carboxamide (Compound A in Table 7 below) are dosed as a suspension at 1 mg/mL in 0.5% Methyl Cellulose/0.5% Tween 80 at a dosing volume of 10 mL/kg to Wistar rats. The diphosphate salt was found to give 1.6× more exposure in terms of AUC (0-24 hours) ng*hr/mL when compared to the sulfate salt. Results are shown below in Table 7.

As shown in Table 7, the mean tmax for sulfate salt is shorter (2.3 hours) versus diphosphate salt (6.7 hours). The mean cmax/dose for phosphate is 303 and for sulfate is 244. The mean auc/dose for phosphate is 4850, for sulfate is 3030. Overall, the sulfate salt showed less exposure in-vivo (about 40% less) than the diphosphate salt.

While the invention has been described above with reference to specific embodiments thereof, it is apparent that many changes, modifications, and variations can be made without departing from the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications, and variations that fall within the spirit and broad scope of the appended claims. All patent applications, patents, and other publications cited herein are incorporated by reference in their entirety.