Highlights
- •Use of saliva as an alternative matrix for monitoring phenytoin drug levels in epileptic patients using RP-HPLC.
- •Samples (trough concentration) both saliva and serum were taken at steady state.
- •There was statistically significant relationship between free serum and salivary phenytoin levels with a p < 0.001.
- •There was a very weak & insignificant correlation between serum/salivary phenytoin levels & sex, age of the study population.
- •The results of the present study support the use of saliva as an alternative to serum/plasma for monitoring phenytoin therapy.
ABSTRACT
Purpose
This study was conducted to examine and verify the use of saliva as an alternative
matrix for monitoring phenytoin drug levels in patients with epilepsy. Drug concentrations
are measured to evaluate whether a suitable drug level has been achieved to minimize
the risk for toxicity, inadequate efficacy, or therapy resistance and compliance issues.
Methods
Quantitative analysis was performed by using reverse-phase HPLC after sample pretreatment
with acetonitrile. Seventy-eight patients who met the inclusion/exclusion criteria
were examined in this study. Trough concentrations of both saliva and serum were taken
at steady state.
Findings
Of the 78 patients enrolled, only 11 (14.1%) had normal levels. Twenty-eight patients
(35.9%) had subtherapeutic levels, and 39 (50%) had toxic levels. Simultaneously,
salivary phenytoin levels were analyzed; only 13 patients (17.3%) had therapeutic
levels, 25 patients (33.3%) had subtherapeutic levels, and 37 (49.3%) had toxic levels.
Among the study population, most of the patients were aged 31 to 40 years (25.6%)
followed by the age group 21 to 30 years (19.2%). The lowest percentage of patients
were in the age groups 71 to 80 years and >80 years (1.3%) each. This study found
a statistically significant relationship between free serum and salivary phenytoin
levels (P < 0.001). A very weak and insignificant correlation was observed between serum/salivary
phenytoin levels and sex/age of the study population. The results of the present study
support the use of saliva as an alternative to serum/plasma for monitoring phenytoin
therapy.
Implications
The free concentration of a drug represents the freely diffusible drug fraction, which
is the therapeutically active form. Accordingly, the free drug concentration correlates
to clinical efficacy and drug toxicity better than total concentration.
Graphical abstract
Graphical Abstract
Key words
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Article info
Publication history
Published online: November 15, 2021
Accepted:
October 17,
2021
Footnotes
Accepted for publication October 17, 2021.
Identification
Copyright
© 2021 Elsevier Inc.
