Therapeutic Monitoring of Anticonvulsants: Use of Saliva as Biological Fluid

Abstract

Plasma drug concentration is not homogeneous within the intravascular space, being the arterial P A ) concentrations higher or lower than that in veins P V ) depending on whether the samples are taken during the drug absorption or the elimination phases, respectively. However, blood samples are currently withdrawn from peripheral veins and total bound plus unbound) plasma drug concentration is assayed. Despite the fact that free plasma drug levels P fV ) are not determined in routine therapeutic drug monitoring TDM), they could be assayed for research purposes. Salivary drug concentrations S) approximate to their free plasma levels in the arteries of the great circulation. Saliva is recommended to be collected with stimulation to minimize the diference between the pHs of both luids saliva and blood), and thus, artery/vein-free drug concentration ratios P fA /P fV ) could be surrogated by the stimulated saliva/freeplasma in vein drug concentration ratios S S /P fV ). It is possible in this way not only to assess this S/P ratio but also to infer the brain B)/P fV ratio, which is actually the most relevant for antiepileptic drugs AEDs). Diferent cases of AEDs are considered in this review, taking into account their physiochemical properties and their ability to be transported by membrane carriers.

The Effect of Plasma Protein Binding on the Therapeutic Monitoring of Antiseizure Medications

“…During the 1970s, saliva was first investigated as an alternative biological fluid to monitor CBZ, PHT, and VPA [ 99 , 100 , 101 , 102 , 103 ]. In the last decade, saliva has been reconsidered as a useful fluid to monitor several ASMs and their free fractions [ 104 , 105 ]. Compared to plasma/blood monitoring, saliva may show some advantages.…”