Background: Immunosuppression regimens in transplantation medicine are complex. Drugs with extended release action have simplified medication dosing without affecting efficacy.
Material and Methods: This prospective, observational, multicenter study, conducted in a routine medical practice setting, evaluated changes in tacrolimus daily dose and trough levels and patient-reported medication adherence at day 90 after 1:1 (mg: mg) conversion to once-daily tacrolimus in adult liver and kidney transplant recipients.
Results: Data from 224 recipients of a liver (n=19) or kidney (n=205) transplant, average age 51±14.5 years, were evaluated. The mean change in tacrolimus daily dose was +0.04 mg/day. Dose remained stable after conversion in 62.5%, was lower in 15.6%, and higher in 22% of patients. Trough level after conversion was lower in 62.6% and higher in 36.5%; generally, levels were 12.8% lower than pre-conversion levels. No acute rejection, graft loss, or serious safety events were observed. Two deaths occurred due to myocardial infarction. Conversion helped 19% to less frequently forget medications and 55% reported no difference in remembering to take the once-daily dose after conversion. The change in dosing frequency was identified as “better” for 55%.
Conclusions: Tacrolimus daily dose remained stable while trough levels were significantly lower after conversion to once-daily dosing. Safety and efficacy were maintained; reduced dosing frequency had no apparent influence on patient-reported medication adherence.

Keywords: medication adherence, Once-daily tacrolimus, Tacrolimus exposure, Organ Transplantation