Salivary anticonvulsant levels in children: a comparison of methods

Area of Science:

• Pharmacology
• Clinical Chemistry

Background:

• Therapeutic drug monitoring (TDM) is crucial for optimizing anticonvulsant therapy in epilepsy.
• Plasma drug level measurements are standard but invasive.
• Saliva offers a non-invasive alternative for drug level assessment.

Purpose of the Study:

• To determine the correlation between plasma and saliva concentrations of key anticonvulsant drugs in epileptic children.
• To evaluate the utility of saliva as a matrix for monitoring anticonvulsant therapy in pediatric epilepsy.

Main Methods:

• Plasma and saliva samples were collected from 202 epileptic children aged 5 months to 18 years.
• Drug levels of phenobarbitone, phenytoin, carbamazepine, and primidone were analyzed using gas-liquid chromatography (GLC) and EMIT immunoassay.
• Saliva-to-plasma concentration ratios were calculated for each drug and method.

Main Results:

• High correlations (r values typically > 0.90) were observed between plasma and saliva drug levels for all four anticonvulsants, regardless of the analytical method used.
• Mean saliva-to-plasma ratios were consistent across methods and comparable to those previously reported in adult populations.
• Phenobarbitone ratios: GLC 0.30±0.05, EMIT 0.31±0.06; Phenytoin ratios: GLC 0.11±0.02, EMIT 0.12±0.04; Carbamazepine ratios: GLC 0.26±0.05, EMIT 0.25±0.06; Primidone ratios: GLC 1.04±0.24, EMIT 0.95±0.20.

Conclusions:

• Saliva drug level measurements provide a reliable and non-invasive method for monitoring anticonvulsant therapy in children with epilepsy.
• The established saliva-to-plasma ratios in adults are applicable to pediatric populations, simplifying therapeutic drug monitoring.