Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1995-03-28
2001-09-11
Raymond, Richard L. (Department: 1624)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Heterocyclic carbon compounds containing a hetero ring...
C544S171000
Reexamination Certificate
active
06288057
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel physical form of a dihydro-2,3-benzodiazepine derivative useful as a pharmaceutical in the treatment of disorders of the nervous system.
1. Background of the Invention
European patent application publication number EP-A1-0492485 discloses the compound 1-(4-aminophenyl)-3-acetyl-4-methyl-7,8-methylenedioxy-3,4-dihydro-5H-2,3-benzodiazepine. The compound is a potent and selective antagonist of the excitatory amino acid AMPA receptor and is believed to have the ability to treat a variety of neurological disorders. The (R)enantiomer of this compound, hereinafter referred to as (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine, is the most potent enantiomer.
2. Summary of the Invention
The present invention provides a physical form of (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine having an X-ray powder diffraction pattern with d spacings at 10.61, 8.83, 6.78, 5.83, 4.13 and 3.74 Å. It also provides a process for producing this form, pharmaceutical compositions containing it and methods of using it.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine is polymorphic.
The first physical form of (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine to be found had a melting point of about 168-172° C. and an X-ray powder diffraction pattern with characteristic d spacings at 6.57 and 5.24 Å. This physical form is referred to hereinafter as form I. It has been prepared by reducing (R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]-benzodiazepine in ethanol using hydrogen and palladium on carbon as catalyst, then removing the catalyst by filtration, evaporating off the ethanol, heating the residue in 5.7 volumes of 1:1 water/ethanol under reflux and then allowing the resultant solution to cool.
Surprisingly, modifying the process used to prepare form I by using ammonium formate and palladium on carbon instead of hydrogen and palladium on carbon gave a new physical form of (R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo [4,5-h][2,3]benzodiazepine, hereafter referred to as form II. Thus form II has been prepared by reducing (R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine in ethanol using ammonium formate and palladium on carbon as catalyst, then removing the catalyst by filtration, evaporating off the ethanol, heating the residue in 6 volumes of 1:1 water/ethanol under reflux, and allowing the resultant solution to cool. Form II has been found to have an X-ray powder diffraction pattern with characteristic d spacings at 13.12 and 5.01 Å.
Modifying the process used to prepare form II by using potassium formate and palladium on carbon instead of ammonium formats and palladium on carbon surprisingly gave yet another physical form, referred to hereinafter as form III. Thus form III has been prepared by reducing (R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine in ethanol using potassium formate and palladium on carbon as catalyst, then removing the catalyst by filtration, evaporating off the ethanol, heating the residue in 6 volumes of 1:1 water/ethanol under reflux and allowing the resultant solution to cool. Form III has been found to have an X-ray powder diffraction pattern with characteristic d spacings at 10.61, 8.83, 6.78, 5.83, 4.13 and 3.74 Å. This physical form is provided as one aspect of the present invention.
Surprisingly, yet another physical form, hereinafter referred to as form IV has also been found. This form was initially observed to have been formed after form II had been heated. It was subsequently found that form IV may be prepared directly by modifying the process used to prepare form III, in particular by increasing the volume ratio of water/ethanol used in the crystallization step. Thus form IV has been prepared by reducing (R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]-benzodiazepine in ethanol using potassium formate and palladium on carbon as catalyst, then removing the catalyst by filtration, evaporating off the ethanol, heating the residue in 8 volumes of 5:3 water/ethanol or 7 volumes of 4:3 water/ethanol under reflux, optionally seeding with Form IV crystals at 70-80° and allowing the resultant mixture to cool. Form IV has been found to have an X-ray powder diffraction pattern with characterization d spacings at 12.78, 9.48, 8.99, 8.64, 8.23, 6.39, 6.27, 5.73, 4.01 and 3.96 Å. This physical form is the subject of a co-pending patent application (ref. X-9386D).
Form I has been found to possess several disadvantageous properties. In particular, it has been found to crystallize out as a thick slurry which is difficult to stir and transfer. The filtration time has been found to be unacceptably long for large scale production, and the drying time for filtered wet cake is also long. Furthermore, Form I has been found to be thermally unstable and has been found to convert to form IV or, occassionally, yet another physical form, hereineafter referred to as form V. Form V has been found to have a X-ray powder diffraction pattern with characterization d spacings at 6.12, 5.94 and 5.48 Å. Form V shows multiple phase transitions when subject to differential scanning calorimetry.
Form II has been found to crystallize out as a stirrable suspension which can readily be filtered. However, it has been found to dry slowly and to retain crystallization solvent. Like Form I, it has been found to be thermally unstable with regard to conversion to form IV.
Form III has been found to crystallize out as a stirrable suspension which can readily be filtered and dried. it has also been found to be thermally stable.
Form IV has also been found to crystallize out as a stirrable suspension which can readily be filtered and dried. Like Form III, it has also been found to be thermally stable.
Each of Forms I, II, III, IV and V has been characterized by a X-ray diffraction, by
13
C solid state NMR spectroscopy and by differential scanning calorimetry. The techniques used, and the physical characteristics determined for samples of each form are given below, together (for form III and IV only) with general ranges obtained by differential scanning calorimetry using a number of different samples.
X-ray diffraction (XRD) patterns were obtained on a Siemens D5000 X-ray diffractometer, equipped with a Cu K&agr; (&lgr;=1.54056 Å) source operating at a tube load of 50KV and 40 mA. Data was collected with a Kevex solid-state detector. Each sample was scanned between 4 and 35° 2&thgr; with a step size of 0.03° and a maximum scan rate of 2 sec/step.
Differential scanning calorimetry (DSC) measurements were performed on a Seiko differential scanning calorimeter. Samples (2-5 mg) sealed in aluminum pans were heated from ambient (25° C.) to at least 200° C. at a rate of 10° C./min.
13
C Cross polarization/magic angle spinning (CP/MAS) NMR spectra were obtained using a Varian unity 400 MHz spectrometer operating at a carbon frequency of 100.577 MHZ and equipped with a complete solids accessory and Varian 5 or 7 mm VT CP/MAS probe. Typical measurement conditions were as follows: 90(deg) proton r.f. pulse 5.0 ms, contact time 1-2 ms, pulse repetition time 5s, MAS frequency 7 kHz, spectral width 50 kHz, and acquisition time 50 ms. The chemical shifts were referenced to the CH
3
group of hexamethylbenzene (delta=17.3 ppm) by sample replacement.
Spacing , d (Å)
Relative intensity
DSC: Major endotherm at 171.5° C., minor endotherm at 207.4° C.
Form I
XRD:
17.30
100
12.28
34
7.76
71
6.57
37
5.24
35
4.81
94
4.34
30
4.21
29
4.09
19
3.9
Eli Lilly and Company
Raymond Richard L.
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