A conscious rat model involving bradycardia and hypotension after oral administration: a toxicokinetical study of aconitine.

1. A model of aconitine-induced bradycardia and hypotension, which is similar to aconitine poisoning in humans, was constructed in conscious rats by oral administration. 2. Blood pressure (BP) and heart rate (HR) of Sprague-Dawley rats were measured using a volume pressure recording (VPR) system. The pharmacokinetics of toxic doses of aconitine and its metabolites were analyzed using UPLC-MS/MS. 3. The HR was significantly decreased by 29% at 2 h after oral administration of 200 µg/kg aconitine. When the dose was increased to 400 µg/kg, systolic BP and diastolic BP were significantly decreased by 11% and 12% at 2 h after the administration, except when bradycardia occurred at 2 h and 4 h. The drug concentration-time curve showed a double-peak phenomenon in rats administered a 400 µg/kg dose. The AUC0-12 h value in the 400 µg/kg group significantly increased 0.8-fold compared to the 200 µg/kg group. Moreover, a high plasma concentration of 16-O-demethyaconitine was found in the rats that received two toxic doses. 4. In conclusion, bradycardia and hypotension are induced in conscious rats by a toxic dose of aconitine (400 µg/kg), and there was no significant difference in dose-normalized AUC0-12 h values between oral administrations of 200 µg/kg and that of 400 µg/kg. However, the dose-normalized Cmax and AUC0-12 h values in 200 µg/kg and 400 µg/kg groups were significantly smaller than those in 100 µg/kg group. The metabolites of aconitine, 16-O-demethyaconitine, and benzoylaconitine may also contribute to the hypotensive response.

Biological activities and pharmacokinetics of aconitine, benzoylaconine, and aconine after oral administration in rats.

Aconitine (AC), benzoylaconine (BAC), and aconine (ACN) are three representative alkaloids in Aconitum tubers. Knowing that the drug disposal process in vivo is closely related to the toxicity and efficacy of a drug, it is important to classify the disposal properties of these alkaloids. In this study, the pharmacokinetics of the three alkaloids was investigated. The results showed that the three alkaloids could be quickly absorbed, especially BAC, whose Tmax was 0.31 ± 0.17 h. Their Cmax was 10.99, 3.99, and 4.29 ng·mL(-1) respectively, indicating that AC had better absorption than BAC and ACN. Subsequently, we further investigated their absorption mechanism using the Caco-2 cell monolayer model in vitro. The results showed that they were poorly absorbed, and the absorption of AC and BAC was inhibited by P-gp, while the absorption of ACN was in a form of passive diffusion. The t1/2 of AC, BAC and ACN was 1.41, 9.49, and 3.32 h, respectively, indicating that the metabolic or excretion rate of AC was quicker than that of BAC and ACN. Therefore, their metabolic stability was further investigated by using rat liver microsomes in vitro, which showed that AC was easier to be metabolized than BAC and ACN. The excretion experiments showed that AC and ACN were primarily excreted in urine, while BAC was excreted in faeces. In addition, the results of tissue distribution experiments showed that the three alkaloids distributed throughout all the organs, although the distribution rate of AC was slower than that of BAC and ACN. Copyright © 2015 John Wiley & Sons, Ltd.

Cardioprotective effect of grape-seed proanthocyanidins on doxorubicin-induced cardiac toxicity in rats.

CONTEXT: Doxorubicin (Dox) is an anthracycline antibiotic used as anticancer agent. However, its use is limited due to its cardiotoxicity which is mainly attributed to accumulation of reactive oxygen species. OBJECTIVE: This study was conducted to assess whether the antioxidant, proanthocyanidins (Pro) can ameliorate Dox-induced cardiotoxicity in rats. MATERIALS AND METHODS: Male Sprague-Dawely rats were divided into four groups. Group I was control. Group II received Pro (70 mg/kg, orally) once daily for 10 days. Group III received doxorubicin 15 mg/kg i.p. as a single dose on the 7th day and Group IV animals were treated with Pro once daily for 10 days and Dox on the 7th day. The parameters of study were serum biomarkers, cardiac tissue antioxidant status, ECG, and effect on aconitine-induced cardiotoxicity. RESULTS: Cardiac toxicity of doxorubicin was manifested as a significant increase in heart rate, elevation of the ST segment, prolongation of the QT interval and an increase in T wave amplitude. In addition, Dox enhanced aconitine-induced cardiotoxicity by a significant decrease in the aconitine dose producing ventricular tachycardia (VT). Administration of Pro significantly suppressed Dox-induced ECG changes and normalized the aconitine dose producing VT. The toxicity of Dox was also confirmed biochemically by significant elevation of serum CK-MB and LDH activities as well as myocardial MDA and GSH contents and decrease in serum catalase and myocardial SOD activities. Administration of Pro significantly suppressed these biochemical changes. DISCUSSION AND CONCLUSION: These results suggest that proanthocyanidins might be a potential cardioprotective agent against Dox-induced cardiotoxicity due to its antioxidant properties.