The invention discloses a method for preparing
nalmefene hydrochloride injection. The method comprises the steps of adding a certain amount of
citric acid or citrate auxiliary material to the preparation when the
nalmefene hydrochloride injection is prepared according to a
common method, wherein the adding amount is 5-15g of
citric acid or citrate added to each
liter of injection; firstly, taking the prescribed auxiliary material in preparation, adding injection water to dissolve, adding
active carbon to agitate and adsorb, filtering and removing impurities; adding the prescribed
nalmefene hydrochloride under the protection of
nitrogen, fully dissolving and
sizing to an appointed constant volume by water, adjusting the pH value to 3.5-4.5; and finally conducting split charging, charging
nitrogen, sealing and sterilizing after filtering by a filter. By adopting the method disclosed by the invention, the validity period of the
nalmefene hydrochloride injection can be obviously prolonged; a specific
citric acid pH value stabilizer is adopted; and the
nalmefene hydrochloride injection has good stability, and stable sample appearance, pH value, effective ingredient content and related substances, and the like. Therefore, the safety of medication is ensured.