Abstract: Packaging assembly intended for the extemporaneous preparation of suspensions or solutions of a solid active product in a liquid product, the active product having been freeze-dried and being contained in a flask A, and the liquid product being contained in a flask B closed by a dropper (30), a connection member (16) enabling to put in communication the two flasks for the purpose, in a first step, to cause the liquid product to pass from flask B into flask A containing the solid product, then, in a second step, to reverse the assembly and aspirate into flask B the suspension or solution thus formed. Flask A containing the active product is closed by an elastic stopper (10) having a central perforation (12) closed by a perforable operculum (14) which is perforated by the dropper when the flasks are put in communication by means of the connection member.