2024 · Journal of clinical psychopharmacology · paywalled
Microsampling Techniques Suitable for Therapeutic Drug Monitoring of Antipsychotics
Geers et al.
The finding, in our words
A review of 18 studies found that microsampling techniques, including dried blood spot sampling and volumetric absorptive microsampling, are validated for antipsychotic monitoring. Although most studies have shortcomings limiting generalisability, microsampling is recommended for clozapine and is a promising, virtually painless option to support decentralised, patient-centric care.
A paraphrase to the Library’s standard, never the abstract. The source is one link away and is always the authority.
In AML and CLL, 91% of VAMS venetoclax results fell within 20% of plasma after individualised haematocrit correction; in home sampling, 18 of 21 patients self-sampled independently and 76% of returned samples were analysable, which shows home microsampling is workable, though the authors ask for multicentre validation.
This review found that volumetric microsampling devices, such as Mitra, HemaPEN, HemaXis DB10, and Tasso-M20, overcome haematocrit bias, whilst Telimmune plasma separation cards enable direct plasma collection without centrifugation. These technologies support patient-centric, decentralised sampling, though the authors note that clinical validation remains limited across different drugs and patient populations.
The study validated an LC-MS/MS method for eight antiepileptic drugs and two metabolites in dried blood spot and VAMS formats, with satisfactory analytical performance and stability, and was the first to include the oxcarbazepine metabolite DHCB. In 80 paired patient samples, microsampling concentrations showed promising correlation with plasma, supporting decentralised therapeutic drug monitoring of antiepileptic treatment.
In matched clinical samples from rheumatoid arthritis, VAMS and DBS showed strong agreement for methotrexate polyglutamates (slopes 0.95-1.07; bias within -4.21% to 0.36%; SRCC ≥ 0.969), with up to 100% of total MTXPG results within ±20% limits; capillary microsampling agreed closely with whole blood but differed from red blood cells, indicating matrix-specific differences that must be accounted for when interpreting against RBC-based reference values.
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.