and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions in all cases the form must be sterile and must be fluid to the extent that easy syringeability exists it must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi the carrier can be solvent or dispersion medium containing for example water ethanol polyol for example glycerol propylene glycol and liquid polyethylene glycol and the like suitable mixtures thereof and vegetable oils the proper consistency can be maintained for example by the use of a coating such as lecithin by the maintenance of the required particle size in the case of dispersion and by the use of surfactants sterile injectable solutions are prepared by incorporating the active compounds in the required amount in the appropriate solvent with various of the other ingredients enumerated above as required followed by filter sterilization generally dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the basic dispersion medium and the required other ingredients from those enumerated above in the case of sterile powders for the preparation of the sterile injectable solutions the preferred method of preparation are vacuum drying and freeze drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile filtered solution thereof the preparation of pharmaceutical compositions is well known in the art and has been described in many articles and textbooks see e g remington 39 s pharmaceutical sciences gennaro a r ed mack publishing.