Aconite poisoning.

Clin Toxicol (Phila). 2009 Apr; 47(4): 279-85Chan TYINTRODUCTION: Aconitine and related alkaloids found in the Aconitum species are highly toxic cardiotoxins and neurotoxins. The wild plant (especially the roots and root tubers) is extremely toxic. Severe aconite poisoning can occur after accidental ingestion of the wild plant or consumption of an herbal decoction made from aconite roots. In traditional Chinese medicine, aconite roots are used only after processing to reduce the toxic alkaloid content. Soaking and boiling during processing or decoction preparation will hydrolyze aconite alkaloids into less toxic and non-toxic derivatives. However, the use of a larger than recommended dose and inadequate processing increases the risk of poisoning. METHODS: A Medline search (1963-February 2009) was conducted. Key articles with information on the use of aconite roots in traditional medicine, active (toxic) ingredients, mechanisms of toxicity, toxicokinetics of Aconitum alkaloids, and clinical features and management of aconite poisoning were reviewed. MECHANISMS OF TOXICITY: The cardiotoxicity and neurotoxicity of aconitine and related alkaloids are due to their actions on the voltage-sensitive sodium channels of the cell membranes of excitable tissues, including the myocardium, nerves, and muscles. Aconitine and mesaconitine bind with high affinity to the open state of the voltage-sensitive sodium channels at site 2, thereby causing a persistent activation of the sodium channels, which become refractory to excitation. The electrophysiological mechanism of arrhythmia induction is triggered activity due to delayed after-depolarization and early after-depolarization. The arrhythmogenic properties of aconitine are in part due to its cholinolytic (anticholinergic) effects mediated by the vagus nerve. Aconitine has a positive inotropic effect by prolonging sodium influx during the action potential. It has hypotensive and bradycardic actions due to activation of the ventromedial nucleus of the hypothalamus. Through its action on voltage-sensitive sodium channels in the axons, aconitine blocks neuromuscular transmission by decreasing the evoked quantal release of acetylcholine. Aconitine, mesaconitine, and hypaconitine can induce strong contractions of the ileum through acetylcholine release from the postganglionic cholinergic nerves. CLINICAL FEATURES: Patients present predominantly with a combination of neurological, cardiovascular, and gastrointestinal features. The neurological features can be sensory (paresthesia and numbness of face, perioral area, and the four limbs), motor (muscle weakness in the four limbs), or both. The cardiovascular features include hypotension, chest pain, palpitations, bradycardia, sinus tachycardia, ventricular ectopics, ventricular tachycardia, and ventricular fibrillation. The gastrointestinal features include nausea, vomiting, abdominal pain, and diarrhea. The main causes of death are refractory ventricular arrhythmias and asystole and the overall in-hospital mortality is 5.5%. MANAGEMENT: Management of aconite poisoning is supportive, including immediate attention to the vital functions and close monitoring of blood pressure and cardiac rhythm. Inotropic therapy is required if hypotension persists and atropine should be used to treat bradycardia. Aconite-induced ventricular arrhythmias are often refractory to direct current cardioversion and antiarrhythmic drugs. Available clinical evidence suggests that amiodarone and flecainide are reasonable first-line treatment. In refractory cases of ventricular arrhythmias and cardiogenic shock, it is most important to maintain systemic blood flow, blood pressure, and tissue oxygenation by the early use of cardiopulmonary bypass. The role of charcoal hemoperfusion to remove circulating aconitine alkaloids is not established. CONCLUSIONS: Aconite roots contain aconitine, mesaconitine, hypaconitine, and other Aconitum alkaloids, which are known cardiotoxins and neurotoxins. Patients present predominantly with neurological, cardiovascular, and gastrointestinal features. Management is supportive; the early use of cardiopulmonary bypass is recommended if ventricular arrhythmias and cardiogenic shock are refractory to first-line treatment.

[Phytochemicals that counteract the cardiotoxic side effects of cancer chemotherapy]

Postepy Hig Med Dosw (Online). 2009; 63: 142-58Piasek A, Bartoszek A, Namieśnik JAlmost all clinically used antitumor drugs exhibit toxic side effects affecting heart function. Because of cardiotoxicity during anticancer chemotherapy, effective doses of cytostatics have to be limited, which may worsen antitumor efficacy. The cardiotoxicity induced by cytostatics of the anthracycline group in particular results, among others, from massive stimulation of ROS. It has therefore been suggested that some phytochemicals with high antioxidant potential, when administered together with antitumor agents, could decrease the toxic side effects of chemotherapy and reduce the risk of heart failure. This review summarizes findings of studies undertaken to identify edible plants or phytochemicals isolated from them displaying cardioprotective properties during chemotherapy. Such properties have been shown for such foods as grapes, garlic,tomato, spinach, and beet root. A protective role on the heart is also displayed by melatonin(a hormone synthesized by the pineal gland, but also present in many edible plants), chalcones(precursors of all known flavonoids), some herbal dietary supplements, vitamins A, C, and E, selenium, and semisynthetic flavonoid 7-monohydroxyethylrutoside (monoHER). Although to date only a limited number of investigations have been carried out, their results suggest that dietary intervention with antioxidants found in edible plants may be a safe and effective way of alleviating the toxicity of anticancer chemotherapy and preventing heart failure.

Evaluation of the hepatotoxic and hepatoprotective effect of Rwandese herbal drugs on in vivo (guinea pigs barbiturate-induced sleeping time) and in vitro (rat precision-cut liver slices, PCLS) models

Exp Toxicol Pathol. 2009 Jun 1; Mukazayire MJ, Allaeys V, Buc Calderon P, Stévigny C, Bigendako MJ, Duez PPrecision-cut liver slices (PCLS) preserve the tissular organization of the organ and represent an in vitro model closer to in vivo conditions than hepatocytes cultures. As this may be an interesting tool not only for the investigation of hepatotoxic and protective effects but also for bioguided fractionations schemes, the usefulness of PCLS was compared with an in vivo test of liver function. Crude extracts derived from five herbs used in Rwanda for hepatoprotective activity were tested on CCl(4)-treated guinea pigs by the method of barbiturate-induced sleep modification. Aqueous extracts of Ocimum lamiifolium, Crassocephalum vitellinum, Guizotia scabra and Vernonia lasiopus leaves allowed animals to recover barbiturate sleep duration in proportions of 88%, 78%, 61% and 34%, respectively and Microglossa pyrifolia was found inactive. Dried methanolic extracts of the 5 plants were then tested in vitro on rat PCLS for protection against acetaminophen-induced hepatotoxicity. In this model, G. scabra, M. pyrifolia and V. lasiopus were found hepatotoxic by themselves and unable to prevent acetaminophen toxicity. The most active extract, obtained from O. lamiifolium, was subjected to bioassay-guided fractionation by chromatography on Si-C(18) to yield two quite active fractions. From a single animal, at least 50 PCLS explants can be prepared, which allows testing large amounts of samples, strengthening ethnopharmacological data on hepatoprotective medicinal plants and investigating hepatotoxic effects.

Status of novel drug delivery technology for phytotherapeutics.

Expert Opin Drug Deliv. 2009 Jun 8; Musthaba SM, Baboota S, Ahmed S, Ahuja A, Ali JHerbal medicines have been widely used all over the world since ancient times and have been recognized by physicians and patients for their better therapeutic value as they have fewer adverse effects as compared with modern medicines. However, phytotherapeutics needs a scientific approach to deliver the components in a sustained manner to increase patient compliance and avoid repeated administration. This can be achieved by designing novel drug delivery systems for herbal constituents. Novel drug delivery systems not only reduce the repeated administration to overcome non-compliance, but also help to increase the therapeutic value by reducing toxicity and increasing the bioavailability, and so on. Recently, pharmaceutical scientists have shifted their focus to designing a drug delivery system for herbal medicines using a scientific approach. For a long time herbal medicines were not considered for development as novel formulations owing to lack of scientific justification and processing difficulties, such as standardization, extraction and identification of individual drug components in complex polyherbal systems. However, modern phytopharmaceutical research solves the scientific needs for herbal medicines as in modern medicine, which gives way for developing novel formulations such as nanoparticles, microemulsions, matrix systems, solid dispersions, liposomes, solid lipid nanoparticles, and so on. This article summarizes various drug delivery technologies for herbal actives, which are gaining more attention for better therapeutic response.

Identification of pregnane x receptor ligands using time-resolved fluorescence resonance energy transfer and quantitative high-throughput screening.

Assay Drug Dev Technol. 2009 Apr; 7(2): 143-69Shukla SJ, Nguyen DT, Macarthur R, Simeonov A, Frazee WJ, Hallis TM, Marks BD, Singh U, Eliason HC, Printen J, Austin CP, Inglese J, Auld DSThe human pregnane X nuclear receptor (PXR) is a xenobioticregulated receptor that is activated by a range of diverse chemicals, including antibiotics, antifungals, glucocorticoids, and herbal extracts. PXR has been characterized as an important receptor in the metabolism of xenobiotics due to induction of cytochrome P450 isozymes and activation by a large number of prescribed medications. Developing methodologies that can efficiently detect PXR ligands will be clinically beneficial to avoid potential drug-drug interactions. To facilitate the identification of PXR ligands, a time-resolved fluorescence resonance energy transfer (TR-FRET) assay was miniaturized to a 1,536-well microtiter plate format to employ quantitative highthroughput screening (qHTS). The optimized 1,536-well TR-FRET assay showed Z'-factors of >/=0.5. Seven- to 15-point concentration-response curves (CRCs) were generated for 8,280 compounds using both terbium and fluorescein emission data, resulting in the generation of 241,664 data points. The qHTS method allowed us to retrospectively examine single concentration screening datasets to assess the sensitivity and selectivity of the PXR assay at different compound screening concentrations. Furthermore, nonspecific assay artifacts such as concentration-based quenching of the terbium signal and compound fluorescence were identified through the examination of CRCs for specific emission channels. The CRC information was also used to define chemotypes associated with PXR ligands. This study demonstrates the feasibility of profiling thousands of compounds against PXR using the TR-FRET assay in a high-throughput format.