Half Syringes of Filler for Sale? Safe?

Once the seal on the syringe is broken, sterility is no longer assured.  "Splitting a syringe before using it" is another bad practice.  There is no practical way to do this and maintain an appropriate level of sterility.  For this reason, the Medicis and Allergan do make smaller syringes although most patients need a full milliliter or more of filler.  Ask yourself, in 6 months, when you do back for the other half of that syringe, how likely is it that you will get your syringe and not Mrs Jones syringe?  Unless your doctor is running a certified tissue bank, it is very improbable that have secure procedures to avoid this type of accident.

This is a bad idea.  Don't use this filler - you have no idea about the sterility.  Throw it away.  I can not recommend this approach at all.