Cilag International Gmbh

Cilag Ag

Pascal Schär

Ulrich Weigl

Alfred Stutz

Process for the preparation of N-methylnaltrexone bromide, wherein a compound of the general formula (I): whereinXrepresents an anion other than the bromide anion, and R represents hydrogen or a leaving group, is dissolved or dispersed in a suitable polar solvent, the solution or dispersion is mixed with a compound containing bromide anions, and the resulting reaction mixture is stirred until N-methylnaltrexone bromide has formed and crystallized, wherein, in the case where R represents a leaving group, that group is removed during or after the reaction.

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Bern, Switzerland

Pascal Schär