Comparison of serum, cerebrospinal fluid and brain extracellular fluid pharmacokinetics of lamotrigine
作者:M C Walker、X Tong、H Perry、M S Alavijeh、P N Patsalos
DOI:10.1038/sj.bjp.0703337
日期:2000.5
We investigated the rate of penetration into and the intra‐relationship between the serum, cerebrospinal fluid (CSF) and regional brain extracellular fluid (bECF) compartments following systemic administration of lamotrigine in rat.
The serum pharmacokinetics were biphasic with an initial distribution phase, (half‐life approximately 3 h), and then a prolonged elimination phase of over 30 h. The serum pharmacokinetics were linear over the range 10–40 mg kg−1.
Using direct sampling of CSF with concomitant serum sampling, the calculated penetration half‐time into CSF was 0.42±0.15 h. At equilibrium, the CSF to total serum concentration ratio (0.61±0.02) was greater than the free to total serum concentration (0.39±0.01).
Using in vivo recovery corrected microdialysis sampling in frontal cortex and hippocampus with concomitant serum sampling, the calculated penetration half‐time of lamotrigine into bECF, 0.51±0.11 h, was similar to that for CSF and was not area or dose dependent. At equilibrium, the bECF to total serum concentration ratio (0.40±0.04) was similar to the free to total serum concentration (0.39±0.01), and did not differ between hippocampus and frontal cortex.
The species specific serum kinetics can explain the prolonged action of lamotrigine in rat seizure models. Lamotrigine has a relatively slow penetration into both CSF and bECF compartments compared with antiepileptic drugs used in acute seizures. Furthermore, the free serum drug concentration is not the sole contributor to the CSF compartment, and the CSF concentration is an overestimate of the bECF concentration of lamotrigine.
British Journal of Pharmacology (2000) 130, 242–248; doi:10.1038/sj.bjp.0703337
在大鼠系统给药后,研究了血清、脑脊液(CSF)和区域脑细胞外液(bECF)隔室的渗透速率及其相互关系。 血清药代动力学为双相,初始分布阶段(半衰期约为3小时),随后是超过30小时的延长消除阶段。血清药代动力学在10–40 mg kg−1范围内呈线性关系。 通过直接采样CSF并同时采集血清样本,计算出渗透入CSF的半衰期为0.42±0.15小时。在平衡状态下,CSF与全血清浓度比值(0.61±0.02)大于游离与全血清浓度比值(0.39±0.01)。 通过在额叶皮层和海马中使用体内恢复校正的微透析取样,并同时采集血清样本,计算出拉莫三嗪渗透入bECF的半衰期为0.51±0.11小时。与CSF相比相似,并且不依赖于区域或剂量。在平衡状态下,bECF与全血清浓度比值(0.40±0.04)类似于游离与全血清浓度比值(0.39±0.01),海马与额叶皮层之间无差异。 特异性血清动力学解释了拉莫三嗪在大鼠癫痫模型中的持久作用。与用于急性 seizure 的抗癫痫药物相比,拉莫三嗪在CSF和bECF隔室中的渗透速度相对较慢。此外,游离血清药物浓度并非CSF隔室的唯一贡献者,CSF浓度过高估计了拉莫三嗪的bECF浓度。 英国药理学杂志 (2000) 130, 242–248; doi:10.1038/sj.bjp.0703337