How to take Rocephin. Rocephin is injected into a muscle, or into a vein through an IV. You may be shown how to use an IV at home. Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of needles, IV tubing, and other items used. You may need to mix Rocephin with a liquid (diluent) before using it. If you are using the injections at home, be sure you understand how to properly mix and store the medication. Use only the diluent your doctor has recommended. Do not mix Rocephin in the same injection with other antibiotics, or with any diluent that contains calcium, including a TPN (total parenteral nutrition) solution.