Phenytoin (PHT) is one of the most commonly used anticonvulsant drugs for the treatment of epilepsy and
bipolar disorders.
The large amount of plasma required by conventional methods for drug quantification makes mass spectrometry
combinedwith dried blood spot (DBS) sampling crucial for pediatric patientswhere therapeutic drug monitoring
or pharmacokinetic studiesmay be difficult to realize. DBS represents a new convenient sampling support requiring
minimally invasive blood drawing and providing long-term stability of samples and less expensive shipment
and storage.
The aim of this study was to develop a LC-MS/MS method for the quantification of PHT on DBS.
This analytical method was validated and gave good linearity (r2= 0.999) in the range of 0–100 mg/l. LOQ and
LOD were 1.0 mg/l and 0.3 mg/l, respectively.
The drug extraction frompaper was performed in a fewminutes using a mixture composed of organic solvent for
80%. The recovery ranged from 85 to 90%; PHT in DBS showed to be stable at different storage temperatures for
one month. A good correlation was also obtained between PHT plasma and DBS concentrations.
This method is both precise and accurate and appears to be particularly suitable to monitor treatment with a
simple and convenient sample collection procedure