Process Or The Preparation Of A Gadolinium Contrast Agent

A process for the preparation of a crystalline Form I of a compound of general formula (I)

• said process comprising:
• providing an aqueous mixture comprising the compound of general formula (I),
• adding an organic solvent and filtering to obtain a solid,
• drying the solid at a relative humidity of from 18% to 70%,
• wherein the crystalline Form I is characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (6.8±0.2)°, (9.1±0.2)° and (11.4±0.2)°, when measured at room temperature with Cu-Kalpha1 radiation having a wavelength of 0.15419 nm.

A process for the preparation of a crystalline Form II of a compound of general formula (I)

• the process comprising:
• providing an aqueous mixture comprising the compound of general formula (I),
• adding an organic solvent and filtering to obtain a solid,
• drying the solid at a relative humidity of from 0% to 25%, followed by a second drying comprising adjusting the relative humidity until a final value of from 18% to 70% is reached,
• wherein the crystalline Form II is characterized by having a powder X-ray diffractogram comprising reflections at 2-Theta angles of (10.2±0.2)°, (10.8±0.2)° and (11.3±0.2)°, when measured at room temperature with Cu-Kalpha1 radiation having a wavelength of 0.15419 nm.