Evaluation of Lipid Emulsion-Mediated Sequestration and Redistribution of the Highly Lipophilic Carbamazepine in the Plasma of Rats

Abstract

Aim: The idea that intravenous lipid emulsion (ILE) may serve as a "reservoir" for lipophilic drugs has emerged in research as an intravascular "lipid sink" effect. Carbamazepine (CBZ) is a widely used anticonvulsant. This compound has a neutral and highly lipophilic structure and can easily cross body membranes. In this study, our hypothesis focused on the potential efficacy of ILE in modulating blood carbamazepine concentrations. Material and Methods: 22 adult Sprague-Dawley rats were divided into four groups. All groups received CBZ at a dose of 20 mg/kg orogastrically. The first group was the control group. In the second group (activated charcoal group), activated charcoal (AC) was administered orogastrically at a dose of 1 g/kg five minutes after orogastric administration of carbamazepine. The third group (lipid group) received ILE at a dose of 3 ml/kg/min at the fifth minute. The fourth group was the saline group, in which 16 ml/kg of 0.9% NaCl was infused at the fifth minute. Blood samples of 0.5 ml were collected at 0, 4, 8, and 24 hours. Plasma was separated by centrifugation (4000 rpm, 10 minutes) and stored at -80oC for determination of CBZ concentrations. An Agilent 6410B HP-1200 LC series (USA) liquid chromatography system was used for analysis. Quantitative analysis was performed in the multiple reaction mode with electrospray positive ionization (ES+). Results: At the 8th hour of orogastric CBZ administration, CBZ concentration was significantly lower in the activated charcoal group than in the lipid and saline groups (p: 0.021; p: 0.023; p<0.05, respectively). There was no significant difference in CBZ concentrations between the other groups at 8 hours (p>0.05). In the lipid group, the increase in CBZ plasma concentrations was statistically significant at 4 and 8 hours compared to 0 hours (p: 0.005; p: 0.005, respectively). Conclusion: In the lipid group, plasma CBZ concentrations increased at 4 and 8 hours in plasma samples from which lipids were separated by differential centrifugation. In the lipid group, no effects favoring drug-lipid sequestration on the plasma distribution of CBZ were observed.