Abstract: FR-PO1184
Drug Formulation Associates with Patterns of Serum Trough Tacrolimus Levels: Experience at a Single Irish Centre
Session Information
- Transplantation: Clinical - Immunosuppression, Adherence, Outcomes
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 1902 Transplantation: Clinical
Authors
- Fitzgerald, Ted J., University Hospital Waterford, Dublin 4, Ireland
- Slattery, Laura M., University Hospital Waterford, Dublin 4, Ireland
- Leavey, Sean F., University Hospital Waterford, Dublin 4, Ireland
Background
Consistently maintaining serum trough tacrolimus levels in the desired therapeutic range is critical to optimise outcomes in kidney transplant recipients. Patients are typically prescribed twice-daily (BD) or once-daily (OD) tacrolimus formulations (e.g. Prograf ® or Advagraf ®). Not uncommonly, patients switch formulation in the course of their follow-up. This study examines associations between BD and OD tacrolimus formulations and achieved serum trough levels (TL) in a cohort of kidney transplant recipients.
Methods
Data pertaining to tacrolimus prescription (date, dose, formulation) and serum TL in kidney transplant recipients was extracted from eMedRenal for a 3-year period (January 2016 to December 2018). Descriptive and inferential analyses were first performed on all TLs in the study population. Mean TL and standard deviations by formulation type were then calculated for each patient. Comparisons of mean TL and standard deviations within subjects who switched formulation during the study period were made by paired samples t-test. The potential for time post-transplant influencing observations was recognised and all analyses were performed in stratified datasets of TL within and after the first post-transplant year.
Results
2870 serum TL were analysed for 142 patients; 67.6% male and 32.4% female with a mean age of 57 (±14) years. The mean allograft vintage in our study population was 8.1 (± 5.7) years. In the 47 patients who switched formulation during the study period, fluctuation in within-patient TL levels was reduced (p<.001), but overall mean serum TL per patient was 1.6ng/mL lower (95% CI,1.18 to 2.04, p<0.001), on OD versus BD tacrolimus.
Conclusion
The differences in serum TL noted by formulation beyond 1-year post-transplant in this cohort were very significant. Furthermore, switching to OD formulations while associated with less fluctuation in levels is associated with lower mean TL. The data emphasises the importance of attending to tacrolimus trough levels, and by implication drug dosing, beyond the first transplant year and especially after switches in formulation.
| <1 year post-transplant | >1 year post-transplant | |
| BD Tacrolimus | n=540 | n=1555 |
| % Trough <4 % Trough 4-9 % Trough >9 | 1.7 63.9 34.4 | 6 79.2 14.8 |
| OD Tacrolimus | n=284 | n=491 |
| % Trough <4 % Trough 4-9 % Trough >9 | 2.1 69.7 28.2 | 11.4 79.2 9.4 |