Objective: This study evaluated the relationship between blood concentration of phenobarbital (PB) and its efficacy as well as adverse events in people with epilepsy in rural China.
Methods: People with epilepsy being treated with PB monotherapy were recruited and followed up for averagely 2.5 years. Data of clinical characteristics were collected using a standardized questionnaire by face-to-face interviews both at baseline and follow-up. Plasma concentration of PB was detected by the high-performance liquid chromatography.
Results: Data on treatment response and PB blood concentration was obtained from 225 subjects. Among them, 119 (52.9%) were recognized as effective cases and 106 (47.1%) as ineffective cases. In the effective group, the blood concentration of 95% subjects ranged from 1.22 μg/ml to 41.36 μg/ml with a median at 13.18 μg/ml (IQR = 8.32-20.19 μg/ml). The PB concentration of 95% of the subjects in the ineffective group ranged from 2.73 μg/ml to 70.16 μg/ml with a median at 19.80 μg/ml (IQR = 11.30-30.40 μg/ml), which was significantly higher than that of the effective group (p < 0.001). Multivariate logistic regression analysis showed that PB concentration ≥26.38 μg/ml was related to a 4.5-fold (95% confidence interval [CI], 1.85-11.08) higher risk of inefficacy. A receiver operation characteristic curve was performed to determine the cutoff value of concentration for PB efficacy at 19.02 μg/ml.
Significance: Blood concentration may be an important indicator for clinical decision making when PB monotherapy cannot achieve a good efficacy and more attention should be paid on it in clinical practice especially in resource-poor settings.
Keywords: Adverse event; Blood concentration; Efficacy; PB monotherapy.
Copyright © 2018. Published by Elsevier Inc.