Crystalline form Calcium (2R,3S)-1-(4-amino-N-isobutylphenylsulfonamido)-4-phenyl-3-(((S)-tetrahydrofuran-3-yloxy)carbonylamino)butan-2-yl phosphate (20-Jan-2010)

Crystalline form

(

Calcium

R,

2

)

S

3

-

-

1

(

-

4

-

amino

-

N

isobutylphenylsulfonamido

)

-

-

4

phenyl

-

(((

-

3

-

)

S

-

tetrahydrofuran

-

3

yloxy

)

)

carbonylamino

-

butan

-

2

yl phosphate

Calcium (2R,3S)-1-(4-amino-N-isobutylphenylsulfonamido)-4-phenyl-3-(((S)- tetrahydrofuran-3-yloxy)carbonylamino)butan-2-yl phosphate("referred as "FSM") of the following formula;

is a phosphate ester prodrug of the protease inhibitor and antiretroviral drug (3S)-oxolan-3-yl N-[(2S,3R)-3-hydroxy-4-[N-(2-methylpropyl)(4- aminobenzene)sulfonamido]-1-phenylbutan-2-yl]carbamate("AMP").

An amorphous form of FSM was found and is described herein below.

    The amorphous form of FSM can be characterized by a powder XRD pattern as depicted in figure 1; a DSC thermogram as depicted in figure 2.

Figure 1 shows a powder XRD pattern of amorphous FSM

Intensity(counts)

4900

3600

2500

1600

900

400

100

0

5 10 15 20 25 30 35

2Theta (°)

Figure 2 shows a DSC thermogram of amorphous FSM

0.6

0.4

0.2

0.0

-0.2

-0.4

-0.6

Exo Down Universal V4.2E TA Instruments

EXAMPLES

PXRD method

Samples after being powdered in a mortar and pestle are applied directly on silicon plate holder. The X-ray powder diffraction pattern was measured with Philips X'Pert PRO X-ray powder diffractometer, equipped with Cu irradiation source =1.54...