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Fingerprick blood samples to measure serum natalizumab concentrations
Alyssa A Toorop1, Maurice Steenhuis2, Floris C Loeff3
1Neurology Outpatient Clinic, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
Background:
Natalizumab via subcutaneous administration was recently approved for patients with multiple sclerosis.
Objective:
In light of personalized extended dosing, in which treatment intervals are prolonged to a concentration cut-off, it would be preferable to measure natalizumab drug concentrations in capillary blood.
Methods:
In this cross-sectional study in patients treated with intravenous (IV) natalizumab, capillary blood samples by fingerprick and venous blood samples were collected in 30 participants prior to IV administration of natalizumab.
Results:
Natalizumab concentrations were similar with a mean bias of -0.36 μg/mL (95% CI: 1.3 to -2 μg/mL).
Conclusions:
This study shows that physicians can monitor natalizumab drug concentrations by a fingerprick, which could be used for personalized extended dosing.

