Yes, heparin can be added to the dialysate containing tobramycin and vancomycin. If the PD fluid if cloudy, you can add 500 units of heparin per 1 L of PD fluid (1000 Units in a 2 L bag) to prevent occlusion of catheter by fibrin. In case of extremely cloudy fluid, some units increase the dose up to 1000 units/L. Once the retrning PD fluid is clear, heparin should be stopped.