P-glycoprotein is responsible for the poor intestinal absorption and low toxicity of oral aconitine: In vitro, in situ, in vivo and in silico studies

• Published in: Toxicology and applied pharmacology 2013-12, Vol.273 (3), p.561-568
• Main Authors: Yang, Cuiping, Zhang, Tianhong, Li, Zheng, Xu, Liang, Liu, Fei, Ruan, Jinxiu, Liu, Keliang, Zhang, Zhenqing
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Aconitine; Aconitine - pharmacokinetics; Aconitine - toxicity; Aconitum; Administration, Oral; ALKALOIDS; Animals; Area Under Curve; ATP-Binding Cassette, Sub-Family B, Member 1 - antagonists & inhibitors; ATP-Binding Cassette, Sub-Family B, Member 1 - metabolism; Biological and medical sciences; Biological Availability; Biological Transport; Caco-2 Cells; Chromatography, Liquid; Cyclosporine - pharmacology; Drug Interactions; GLYCOPROTEINS; HERBS; Humans; In situ intestinal perfusion; INTESTINAL ABSORPTION; Intestinal Absorption - drug effects; Intestines - drug effects; Intestines - metabolism; Male; MDCKII-MDR1 cells; Medical sciences; Oral absorption; P-glycoprotein; PERMEABILITY; Plant Extracts - pharmacokinetics; Plant Extracts - toxicity; Protein Conformation; RATS; Rats, Sprague-Dawley; Tandem Mass Spectrometry; TOXICITY; Toxicology; Verapamil - pharmacology
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2013.09.030

Aconitine (AC) is a highly toxic alkaloid from bioactive plants of the genus Aconitum, some of which have been widely used as medicinal herbs for thousands of years. In this study, we systematically evaluated the potential role of P-glycoprotein (P-gp) in the mechanisms underlying the low and variable bioavailability of oral AC. First, the bidirectional transport of AC across Caco-2 and MDCKII-MDR1 cells was investigated. The efflux of AC across monolayers of these two cell lines was greater than its influx. Additionally, the P-gp inhibitors, verapamil and cyclosporin A, significantly decreased the efflux of AC. An in situ intestinal perfusion study in rats showed that verapamil co-perfusion caused a significant increase in the intestinal permeability of AC, from 0.22×10−5 to 2.85×10−5cm/s. Then, the pharmacokinetic profile of orally administered AC with or without pre-treatment with verapamil was determined in rats. With pre-treatment of verapamil, the maximum plasma concentration (Cmax) of AC increased sharply, from 39.43 to 1490.7ng/ml. Accordingly, a 6.7-fold increase in the area under the plasma concentration–time curve (AUC0–12h) of AC was observed when co-administered with verapamil. In silico docking analyses suggested that AC and verapamil possess similar P-gp recognition mechanisms. This work demonstrated that P-gp is involved in limiting the intestinal absorption of AC and attenuating its toxicity to humans. Our data indicate that potential P-gp-mediated drug–drug interactions should be considered carefully in the clinical application of aconite and formulations containing AC. [Display omitted] •Verapamil and cyclosporin A decreased the efflux of aconitine across Caco-2 cells.•Both inhibitors decreased the efflux of aconitine across MDCKII-MDR1 cells.•Co-perfusion with verapamil increased the intestinal permeability of aconitine.•Co-administration with verapamil sharply increased the Cmax and AUC of aconitine.•P-gp interacted with both verapamil and aconitine and recognized them similarly.