In Mexico, plasma drug quantitation is utilized to check dose titration, compliance, and toxicity in treatment with antiepileptic drugs like valproic acid (VPA), but without considering the pharmacokinetic principles due to the absence of clinical pharmacists in the Health System. This study analyzed the within-patient relationship between dosage and plasma VPA concentrations in different age groups, to evaluate the effect of enzyme-inducing co-medication, and to evaluate the efficiency of the monitoring process performed in a pediatric hospital, to make the pertinent recommendations. This retrospective observational analysis, lasted one year, performed in a pediatric hospital in Hidalgo, Mexico.
This retrospective analysis included the plasmatic concentration data of VPA in pediatric patients of 1 to 15 years old, who had received a reliable diagnosis of epilepsy. Microsoft Excel® was used for the statistical analysis of the data. Files of 260 patients were reviewed. It was found that only 56.5% of the patients had serum levels at a steady state. The plasma VPA levels were found in the sub-therapeutic level in 22% of patients and 15% had toxic levels. The analysis showed that children under five years of age appear as a heterogeneous group for the variables studied. However, the difference in plasma concentrations was not statistically significant (p<0.05). Due to the lack of recognition of clinical pharmacists in Mexico, we recommend that the best clinical outcome can only be assessed by monitoring pharmacokinetic parameters for changes occurring in each patient, and not just through trial and error dosing.
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