2019 · American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons · paywalled
Assessment of tacrolimus intrapatient variability in stable adherent transplant recipients: Establishing baseline values
Leino et al.
The finding, in our words
In highly adherent transplant recipients who collected dried blood spots at home, tacrolimus showed modest intrapatient variability with a median coefficient of variation of 15.2 per cent. This provides a baseline to help distinguish pharmacokinetic variation from non-adherence in decentralised therapeutic drug monitoring.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
The study found that quantitative dried blood spot sampling provided high clinical agreement for tacrolimus and creatinine monitoring, with patients rating the self-collection devices as user-friendly. These results support the feasibility of decentralised therapeutic drug monitoring for immunosuppressants.
A systematic review found mixed economic evidence for microsampling in therapeutic drug monitoring; one study reported no cost reduction with DBS home-sampling, €688 versus €676, whilst another predicted savings up to 61%. The authors caution that more work is required to assess costs alongside clinical outcomes and optimise logistics for decentralised implementation.
VAMS microsampling found no significant difference from venous blood for tacrolimus in paediatric patients; samples were stable for 14 days, with average difference between paired at-home samples of 0.12 ± 0.94 ng/mL.
This review surveys published LC-MS/MS methods that use dried blood microsampling for therapeutic drug monitoring of immunosuppressants in transplantation, chemotherapy and autoimmune disease, finding that volumetric dried blood samples can replace conventional venous draws for home sampling and improve patient quality of life. The authors discuss pre-analytical considerations, clinical applicability, cost-effectiveness, harmonisation gaps and patient perception, concluding that obstacles to routine clinical implementation remain despite growing methodological maturity.
Clinical validation for tacrolimus and mycophenolic acid monitoring showed that while volumetric absorptive microsampling met analytical criteria after concentration correction, conventional dried blood spots achieved superior adherence to strict clinical criteria, sample quality, and cost efficiency without significant haematocrit bias.