Conventional Dialysis
Vancomycin is removed almost entirely by the kidneys, so its removal from the body takes longer in dialysis patients. A single dose usually takes longer than a week to be completely eliminated. Since the clearing of vancomycin by conventional hemodialysis is considered negligible, a single weekly dose of vancomycin has long been used.In this strategy, the patient usually receives of 1000 mg (or 1 gram) of vancomycin followed by drug level monitoring. The amount and frequency of the subsequent doses are then based on these blood levels, but they are typically weekly. Patients with some remaining kidney function typically require more frequent dosing.
High-Efficiency Dialysis
Over the last decade or so, there has been a shift to higher-efficiency dialysis, known as high-flux dialysis. Research has shown that this type of therapy is not only better at removing toxins, but at removing vancomycin as well. As a result, a drop in vancomycin levels between doses can lead to infections failing to respond to vancomycin. To address this problem, alternative approaches have been suggested as a way to ensure appropriate levels of vancomycin.
Alternate Dosing Regimen 1
In one strategy, there is an initial weight-based dose of vancomycin (20 mg/kg) followed by a fixed amount (500 mg) after each high-flux dialysis treatment, until the therapy is complete. Although the initial dose is, in theory, based on the person’s weight (in kilograms), it is common to set a lower limit of 750 mg for the initial dose, regardless of their weight.For example, a person weighing 110-pound (or 50 kilograms) would receive an initial dose of 1000 mg or 1 gram (50 kg x 20 mg/kg = 1000 mg).
Alternate Dosing Regimen 2
Some kidney doctors feel that the previous dosing regimen leads to inappropriately low drug levels right after starting the treatment. As a result, it is not uncommon to start by giving a higher initial dose (30 mg/kg), followed by half that amount (15 mg/kg), and then finally a smaller dose (500 mg) for each subsequent treatment until the therapy is complete.Using this regimen, the same 50-kilogram person would receive an initial dose of 1500 mg (50 kg x 30 mg/kg) followed by 750 mg (50 kg x 15 mg/kg). Assuming adequate drug levels, the remaining doses would be all 500 mg.
Conclusion
Vancomycin is an important drug in the treatment of infections in dialysis patients. The increased efficiency of dialyzer treatments over the last decade or so has led to a change in the way it is given. No regimen has yet been shown to be consistently better to others, so the choice of which to use is often left up to the discretion of the doctor.
Note that the current dosing regimens described above assume that the blood levels of the drug are found within an acceptable range. Depending on the results, the amount and/or frequency of the dosing may change.
Sources:
Lentino, Joseph and Leehey, David. “Infections.” Handbook of Dialysis 3rd Edition. Eds. Daugirdas, Blake & Ing. Philadelphia: Lippincott Williams & Wilkins, 2001. 495-521.