Higher Starting Dose of Ciclosporin Optimized Therapeutic Levels in Patients Receiving Phenytoin for Busulfan-induced Seizure Prophylaxis.

Background: Despite understanding the drug-drug interaction between phenytoin and ciclosporin (CsA), there is no recommended CsA dosing in patients receiving phenytoin as seizure prophylaxis in busulfan-based conditioning regimens. This drug-drug interaction has resulted in patients with sub-therapeutic levels at day 0 (D0) of allogeneic hematopoietic stem cell transplantation (alloHSCT) and at risk for acute graft-versus-host disease (aGVHD).

Objective/methods: A single-center historical-control study was conducted at Singapore General Hospital between March 2010 and July 2019 to evaluate a new dosing strategy.