Managing Drug Interactions in Cancer Therapy: A Guide for the Advanced Practitioner.

Mrs. P is a 30-year-old woman who presented to our bone marrow transplant program with myelodysplastic syndrome (MDS). She received a haploidentical allogeneic stem cell transplant with a conditioning regimen consisting of busulfan and cyclophosphamide. This treatment was followed by post-transplant immunosuppression for graft-versus-host disease (GVHD) with cyclophosphamide, mycophenolate mofetil (MMF), and tacrolimus (see Table 1 for medication list). Tacrolimus levels were monitored twice a week with adjustment to a goal range of between 5 and 10 ng/mL. We initiated tacrolimus at a dose of 0.03 mg/kg by mouth twice daily (rounded to 2 mg by mouth twice daily). Drug interactions were assessed by the clinical pharmacist prior to admission, routinely with medication changes, and then upon discharge.