| abstract |
The invention relates to a novel process for preparing N-methylnaltrexone bromide, comprising at least the steps consisting in: (i) reacting N-methylnaltrexone methyl sulphate in an aqueous solution with an alkaline agent chosen from the group consisting of sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, caesium carbonate and strontium carbonate, and mixtures thereof, for a pH of the aqueous reaction medium of between 7 and 10, and then in (ii) reacting the product thus obtained with hydrobromic acid which is added for a pH of the aqueous reaction medium of between 0.5 and 5, and thus obtaining N-methylnaltrexone bromide. |