Abstract
The recent reports from Hong Kong, Taiwan, China and Korea were reviewed to determine the causes and prospects for prevention of herb-induced aconite poisonings. The contributory factors included overdose (use of greater than the recommended doses), faulty processing (after harvest and during decoction), use of tincture (herbal medicinal wine), use of crude aconite roots (for preparing decoction, proprietary medicines and tincture), lack of standardisation in processing of aconite roots and preparation of tincture and proprietary medicines, unsupervised use of aconite roots and contamination or mix-up with aconite roots. As tincture (herbal medicinal wine) made from aconite roots contains a much larger amount of Aconitum alkaloids, the public should be strongly discouraged from making their own and taking it by mouth. Aconite roots should only be used after post-harvest processing and proper decoction. The public should be educated on the hazards from unsupervised use and improper decoction of processed aconite roots. There should be regular publicity measures to promote awareness among the herbalists and to publicise the risk of serious cardiotoxicity if the recommended doses of processed aconite roots are exceeded. The processing of aconite roots and their proprietary preparations should be standardised. Quality control of processed aconite roots and their proprietary preparations should be strengthened. National reporting or monitoring systems can be used to identify the causes of aconite poisonings and assess the impact of preventive measures.
Introduction
Aconitine, mesaconitine, hypaconitine, yunaconitine and other Aconitum alkaloids are known cardiotoxins and neurotoxins found in all parts of the Aconitum species, especially the roots and root tubers (aconite roots). 1 Because of the continuing use of aconite roots in traditional medicine and homeopathic medicine as analgesic, anti-inflammatory and cardiotonic agents and for other indications, aconite poisonings remain common in Asia. 2 In subjects with herb-induced aconite poisoning, a combination of neurological, gastrointestinal and cardiovascular features is seen, including generalised numbness and muscle weakness, nausea, vomiting, abdominal pain, diarrhoea, hypotension, palpitations, sinus tachycardia, ventricular ectopics, ventricular arrhythmias and asystole.3–5
In view of the risk of ventricular arrhythmias and asystole, it is important to determine the causes and prospects for prevention of herb-induced aconite poisonings.
Subjects and methods
A Medline search was conducted to identify reports of herb-induced aconite poisonings that were published in the indexed journals. Mainly the post-2004 case series and predisposing factors were analysed since this review focused on the reasons for the continuing occurrence of herb-induced aconite poisonings in Asia. The earlier studies, including clinical features of aconite poisonings, were mostly covered in a recent review. 5 To identify reports from China and Korea that were published in the non-indexed journals, a search of China Academic Journals Full-text Database (CAJ) and Korean Medical Citation Index was performed. These articles were not reviewed previously as they could not be identified by a Medline search. Aconite, aconitine, Aconitum and these terms in Chinese were used as the key words in the search. Additional articles were identified from the herbal medicine database of the Prince of Wales Hospital Poison Treatment Centre.6,7 Reports of aconite poisonings related to ingestion of the wild plants or homicidal use of aconite roots were not included.
Results
The recent reports of herb-induced aconite poisonings from Hong Kong, Taiwan, China and Korea are summarised in Table 1. As demographic and clinical data were either incomplete or unavailable, such information is not shown.
The recent reports of herb-induced aconite poisonings
AR: aconite roots, Ext: aconite root preparations for external use, P: powdered aconite roots to be dissolved in water, PAR: proprietary preparations of aconite roots, T: aconite tincture (herbal medicinal wine), U: unknown.
a Tincture was regarded as a cause because it contained a large amount of Aconitum alkaloids.
Hong Kong
From January 2000 to June 2005, the Department of Health received 15 reports of adverse reactions to processed aconite roots.6,7 In 14 patients, overdose (use of greater than recommended doses of 1.5–3.0 g) was the main cause of poisoning and inadequate decoction was a contributory factor. In one patient, unintended exposure to aconite roots occurred as a result of erroneous substitution. In addition, proprietary preparation of aconite roots was the cause of poisoning in one patient. The dose of aconite roots involved was not stated.
The territory-wide Toxicology Reference Laboratory reported a change in the pattern of aconite poisoning. 8 From March 2004 to June 2005, there were 10 confirmed cases of aconite poisoning, but no aconite roots were found in the written prescriptions of four cases. The presence of yunaconitine (predominately found in the Aconitum species of Yunnan) in the leftover herbal broth and urine samples of these four patients suggested that inadvertent contamination or mix-up with such Yunnan Aconitum species was a possible explanation.8,9 In the six patients with aconite roots listed in the prescriptions, 8 the doses involved were not mentioned in the study.
Taiwan
In 1990–1999, the National Poison Center received 17 reports of aconite poisoning. 4 Ten patients took a decoction made from unprocessed (n = 4) or processed (n = 6) aconite roots, but none of them prepared the decoction by adequately boiling aconite roots in water. One patient took processed aconite root instead of the decoction made from it. Four patients ingested a tincture made from unprocessed aconite roots and wine. Two patients took a proprietary preparation of aconite roots.
China
In China, Yu et al. 10 reviewed 386 reports of aconite poisonings that were published in the Chinese Journals during 1989–2008. All these reports had fairly complete information on the presenting complaints of the affected subjects and the aconite root preparations used. A total of 2,017 cases were reviewed. ‘Caowu’ (the root tuber of A. kusnezoffii), ‘chuanwu’ (the root tuber of A. carmichaeli) and ‘fuzi’ (the lateral root tuber of A. carmichaeli) were responsible for 35.0%, 25.9% and 13.8% of cases, respectively. Tincture (herbal medicinal wine), powdered forms, herbal decoction, proprietary medicines and topical preparations accounted for 55.5%, 12.4%, 11.8%, 2.6% and 1.7%, respectively. In the remaining 16.0% of cases, the preparations used were not clearly mentioned in the original papers. The aconite root preparations for external use were not described by Yu et al. 10 However, a review of the CAJ database indicated that these 34 cases (Table 1) mostly involved aconite tincture (herbal medicinal wine) for external use, which was intentionally or unintentionally taken by mouth. There could be occasional reports of percutaenous absorption and systemic toxicity following the excessive use of aconite tincture over wounds. The processed aconite root powders were usually taken after being placed in a glass of hot water.
Korea
Aconite poisonings occurred mostly after the consumption of decoction, tincture (herbal medicinal wine) and unrefined tablets prepared from crude aconite roots.11–14 Aconite poisonings could occur regardless of the number of tablets of ingested, reflecting the risk of inadequately processed aconite roots in proprietary preparations. 13
Discussion
The causes for aconite poisonings and types of aconite preparations involved varied between Asian countries (Table 1). In Hong Kong, overdose (use of greater than recommended doses of 1.5–3.0 g) of processed aconite roots was the main cause and inadequate decoction was a contributory factor.6,7 Processed aconite roots should be decocted for 1 to 2 hr before boiling with other herbs. 7 This is an important step to reduce their toxicity.5,7 Those without proper consultation with the herbalists were not aware of this important step. 7 During 2004–2006, inadvertent contamination or mix-up with the Yunnan Aconitum species emerged as an important cause of aconite poisonings. 8 Since the presence of aconite roots was unknown to the patients, the important step of prolonged boiling to reduce toxicity would not be followed. Thus, these patients were at an increased risk of aconite poisonings. In Taiwan, inadequate decoction of unprocessed and processed aconite roots and aconite tincture accounted for the majority of cases of aconite poisonings. 4 Raw aconite roots are very toxic and should first be processed before use. Post-harvest processing reduces the Aconitum alkaloid contents by up to 90%. 3 Soaking and boiling during decoction hydrolyses the remaining alkaloids into the less toxic and non-toxic derivatives.5,15 Use of unprocessed aconite roots, faulty processing after harvest and improper decoction will increase the risk of aconite poisonings because the amounts of Aconitum alkaloids taken by the patients would be much larger than intended. In China, herb-induced aconite poisonings were predominately caused by ingestion of tincture (herbal medicinal wine). In preparation of tincture (herbal medicinal wine), the crude plants (the whole plant or root tubers) are often used without prior processing. Also, because the quantities of aconite roots added and the methods used are not standardised and Aconitum alkaloids dissolve well in alcohol, tincture (herbal medicinal wine), especially the homemade one, is particularly toxic because of the large amounts of Aconitum alkaloids involved.4,5,10 Aconite root powders are also associated with a higher risk of poisoning as they are taken without boiling. In Korea, herbal decoction, tincture (herbal medicinal wine) and unrefined tablets prepared from crude aconite roots could all cause aconite poisonings.11–14 In preparation of proprietary medicines, processed aconite roots, instead of unrefined aconite roots, should have been used. However, proprietary medicines made from processed aconite roots still cause poisonings because these herbs are intrinsically toxic especially after overdose.4–6
Based on the recent reports (Table 1), the contributory factors to aconite poisonings in Asia included overdose (use of greater than the recommended doses), faulty processing (after harvest and during decoction), use of tincture (herbal medicinal wine), use of crude aconite roots (for preparing decoction, proprietary medicines and tincture), lack of standardisation in processing of aconite roots and preparation of tincture (herbal medicine wine) and proprietary medicines, unsupervised use of aconite roots and contamination or mix-up with aconite roots. As tincture (herbal medicinal wine) made from aconite roots contains a much larger amount of Aconitum alkaloids,4,5,10 the public should be strongly discouraged from making their own and taking it by mouth. Aconite roots should only be used after post-harvest processing and proper decoction. The public should be educated on the hazards from unsupervised use and improper decoction of processed aconite roots. There should be regular publicity measures to promote awareness among the herbalists and the public the risk of serious cardiotoxicity if the recommended doses of processed aconite roots are exceeded. 16 The processing of aconite roots and their proprietary preparations should be standardised. Quality control of processed aconite roots and their proprietary preparations should be strengthened. National reporting or monitoring systems can be used to identify the causes of aconite poisonings and assess the impact of preventive measures.6–8
Footnotes
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.