ABSTRACT
Objective To study the in situ intestinal absorption characteristics of cyclovirobuxine D (CB) hydroxypropyl-β-cyclodextrin inclusion complex (CBHD) in rats, and to explore the effect of cytochrome P450 inhibitor ketoconazole (KET) on CB and CBHD in situ intestinal absorption. Methods Twenty-four male rats were randomized into CB, CBHD, KET+CB and KET+CBHD groups, with 6 rats in each group. In situ intestinal absorption was adopted in a rat model. One-way intestinal perfusion model was employed to investigate the absorption of CB and CBHD in the intestinal segments of rats and the effects of KET on CB and CBHD absorption. The concentration of CB was determined by highperformance liquid chromatography with fluorescence detector (HPLC/FLD; Lichrospher C18 column [250 mm×4.6 mm, 5 μm]). The mobile phase was methanol-water with volume ratio being 85: 15. The excitation wavelength was set at 231 nm, and emission wavelength was set at 385 nm. The column temperature was 25 °C, and flow rate was 1.0 mL/min. The injection volume was 20 μL. Results The specificity of HPLC/FLD method was good and the standard curve equation was A=106.7 C+41.861 (R2=0.999 08) based on the linear regression of CB concentration (C) with CB peak area (A), indicating that the CB mass concentration was linear in the range of 0.5 to 20.0 μg/mL. The intra-day precision of the 1.0, 5.0 and 10.0 μg/mL samples was 2.25%, 2.44% and 3.04%, and the inter-day precision was 4.22%, 2.00% and 2.50%, respectively. The precision was good and the method was in accordance with the requirements of methodology. The recovery rates of the 1.0, 5.0 and 10.0 μg/mL samples were 99.08%, 98.24% and 97.25%, respectively, which were also in accordance with the requirements of methodology. The intestinal absorption rate constant (Ka) values of CBHD with KET were 4.18, 5.05, 1.91 and 2.85 times those of CB, and the effective permeability (Peff) values were 4.92, 5.98, 2.19 and 3.24 times those of CB in the duodenum, jejunum, ileum and colon, respectively (all P<0.05). Conclusion KET can improve the intestinal absorption of CB and CBHD in rats.
ABSTRACT
This study is to investigate the effects of phenytoin sodium, lidocaine (sodium channel blockers), propranolol (beta-adrenergic receptor antagonist), amiodarone (drugs prolonging the action potential duration) and verapamil (calcium channel blockers) on arrhythmia of mice induced by Bufonis Venenum (Chansu) and isolated mouse hearts lethal dose of Chansu. Arrhythmia of mice were induced by Chansu and then electrocardiograms (ECGs) were recorded. The changes of P-R interval, QRS complex, Q-T interval, T wave amplitude, heart rate (HR) were observed. Moreover, arrhythmia rate, survival rate and arrhythmia score were counted. Isolated mouse hearts were prefused, and the lethal dose of Chansu was recorded. Compared with control group, after pretreatment with phenytoin sodium, broadening of QRS complex and HR were inhibited, and the incidence of ventricular arrhythmia was reduced dramatically, while survival rate was improved; the isolated mouse hearts lethal dose of Chansu was increased significantly. After pretreatment with lidocaine, the prolongation of P-R interval and broadening of QRS complex were inhibited, and the incidences of ventricular arrhythmia were reduced dramatically, while survival rate was improved; the isolated mouse hearts lethal dose of Chansu was increased significantly. After pretreatment with propranolol, prolongation of P-R interval, broadening of QRS complex, prolongation of Q-T interval and HR were inhibited, and the incidences of both supraventricular and ventricular arrhythmias were reduced dramatically, while survival rate was improved. After pretreatment with amiodarone, HR was inhibited, the incidences of ventricular tachycardia were reduced dramatically. Lastly, after pretreatment with verapamil, the prolongation of P-R interval and Q-T interval were inhibited and the incidences of both supraventricular and ventricular arrhythmias were reduced dramatically; the isolated mouse hearts lethal dose of Chansu was reduced significantly. In in vivo experiments, phenytoin sodium was most effective against the mice arrhythmias induced by Chansu while cautious use of verapamil for Chansu inducing arrhythmia should be noted. It is also concluded that mice ventricular arrhythmias induced by Chansu might be most closely related to sodium channel, supraventricular arrhythmias might be related to beta-adrenergic receptor, and calcium channel plays an important role in conduction block. In in vitro experiments, phenytoin sodium was most effective, followed by lidocaine and propranolol, and amiodarone had no obvious effect and verapamil reduced the lethal dose of Chansu.