spp. (chuan mu tong), Akebia spp. (bai mu tong) and Aristolochia
manshuriensis (guan mu tong). Of the 14 samples tested, a raw herbal
material and a manufactured clematis product were found to contain
Aristolochia. In TCM Aristolochia spp. are considered to be interchange-
able with other commonly used herbal ingredients and substitution of one
plant for another species is an established practice, when in fact this may
not be the case (Table 6.4).
Pharmokinetic data for aristolochic acids 1 and 11 have been studied in
rats, mice, guinea-pigs, dogs and humans after oral treatment.^192 The doses
studied were in the range 0.6–85 mg/kg body weight. Most of the results
relate to rats. After oral administration, aristolochic acid 1 was readily
absorbed from the gastrointestinal tract. After oral administration of
aristolochic acid 1 to rats, about 91% of the dose was recovered from the
excreta, equally divided in the urine and faeces.
In vivo and in vitro studies have shown that aristolochic acids are both
nephrotoxic and carcinogenic. Hence most European Union states have
taken regulatory action to protect the public from unlicensed medicines that
contain Aristolochia. In many member states (including the UK) Stephania
tetrandra, Akebia and Clematis spp. are also being controlled because of the
risk of substitution. Following the interim measures taken in July 1999, the
UK MHRA introduced a permanent ban on the import, sale or supply of
preparations containing plants of the genus Aristolochiaand of Akebiaand
Clematis spp. used asmu tong. It is unfortunate that such action is neces-
sary and some would say that this represents another example of the
government restricting consumers’ choice.
There is undoubtedly a substantial potential risk to health from Aris-
tolochia. Effective control is vital to ensure that the herb is used under
appropriate supervision and is of the highest quality. Aristolochia has been
a POM since 1997 but exempt from control when used in herbal or
homoeopathic medicine. Homoeopathic medicines were unaffected by the
legislation, although it is possible that at a later date the potencies (strengths)
available could be restricted to those above 9c, when the dilution is of such
magnitude that no molecules of drug are considered to be present.
Traditional Chinese medicine | 169Species Part used Indication
A. fangchi Root Diuretic, antirheumatic
A. contorta, A. debilis Fruit Antitussive, antiasthmatic
A. contorta, A. debilis Herb Diuretic and anti-inflammatory
A. debilis Root AnalgesicTable 6.4Species of Aristolochia