Platelet Dysfunction Because of Amlodipine in Bone Marrow Transplant Recipient

Background: Hypertension (HTN) is a complication of pediatric hematopoietic stem cell transplantation. We report a pediatric stem cell transplant patient who had HTN and adverse event because of amlodipine. Observation: Seven-year-old boy had haploidentical stem cell transplantation with post-transplant cyclophosphamide. He had complete donor chimerism at the end of one month. Amlodipine was started on day +36 for HTN. On day +41, he had petechiae. Platelet function analyzer (PFA)-100 was abnormal. After amlodipine was stopped, petechiae disappeared and PFA-100 returned to normal. Conclusions: Abnormal PFA-100 and the patient complaints indicated the possibility of amlodipine-induced platelet dysfunction through inhibition of calcium-mediated platelet reactions.