We Claim:
!. Stable amorphous form of Remimazolam losylate.
2. A process for the preparation of stable amorphous form of Remi triazolam tosylate comprising:
a) dissolving Remimazolam tosylate in a solvent mixture of alcohol and water;
b) optionally filtering the reaction mixture obtained in step-a);
c) lyophilizing the solution obtained in step-b); and
d) isolating the stable amorphous form of Remimazolam tosylate.
3. The process as claimed in claim 2, wherein the alcohol solvent used in the step a) is selected from methanol, ethanol, propanol, isopropanol, butanol or a mixture thereof.
4. Crystalline Form-G of Remimazolam tosylate characterized by a powder-X-ray diffracton spectrum having peaks at 2-theta values of about 2.09°, 6.27°, 6.95°, 11.64°, 11.95°, 13.93°, 14.50°, 15.12°, 17.91°, 18.86°, 19.92°, 20.99°, 21.37°, 23.46°, 24.21 °, 26.19° and 27.40° ± 0.2° " theta and PXRD pattern as mentioned in figure-3.
5. A process for the preparation of crystalline Form-G of Remimazolam tosylate comprising:
a) dissolving Remimazolam in an organic solvent;
b) addition of para toluene sulfonic acid monohydrate to the reaction mixture obtained in step-a); and
c) isolation of crystalline Form-G of Remimazolam tosylate.
6. The process as claimed in claim 5, wherein the organic solvent used in step a) is an ester solvent selected from ethyl acetate, methyl acetate or isopropyl acetate; alcohol solvent selected from methanol, ethanol, propanol, butanol, isopropanol or a mixture thereof
7. A process for the preparation of amorphous form of Remimazolam tosylate as claimed in claim 2-3, characterized by differential scanning calorimetry having an endotherm at range of about 186°C and 206°C.
8. A process for the preparation of crystalline Form-G of Remimazolam losylate as claimed in claim • 5-7. characterized by differentia! scanning calorimelry having an endolherm at range of about 188°Cand206°C
9. A method for preparing pharmaceutical composition comprising Remimazolam tosylate of claim 1-7 and atleast one pharmaceutical!)' acceptable excipient.