A retractable needle syringe having a conical frustum tip configured to selectively attach to a Luer device including an inexpensive commonly found Luer filling needle, and also including an interchangeable needle assembly configured to secure to a needle stem positioned within the conical frustum tip. The conical frustum tip advantageously facilitates aspirating a medicant, using a common Luer needle for filling and also prevents the possible unintentional retraction of the needle assembly due to hydraulic pressures encountered when drawing the medicant from a vial and during the handling of the syringe. Moreover, the conical frustum tip advantageously allows the syringe to be conveniently prefilled with a medicant at a pharmacy and capped, then transported to a patient with or without needle assembly as desired. This design is a significant advantage for many healthcare workers involved in the processing and handling of syringes until ultimate delivery of the medicant to a patient.
