The popular herbal remedy kava, commonly used to treat stress and anxiety, has been banned in the UK by the Medicines Control Agency (MCA) following concerns that it can lead to liver poisoning. The UK previously issued a voluntary ban of the herb earlier this year.
The MCA said it will place an Order prohibiting the supply of medicinal products containing kava-kavabefore parliament today. The Order, which will come into force on 13 January 2003, will prohibit the sale, supply or importation of unlicensed medicinal products containing the herb.
The action follows concerns throughout Europe after several cases of liver toxicity were reported. Several other European countries have already removed the herb from the market. In the UKthese concerns have been under investigation since December 2001, when avoluntary withdrawal of all stocks of kava containing products wasundertaken by the herbal sector following advice from the MCA.
The UK's Food Standards Agency has created parallel legislation to ensure thatkava-kava is no longer used in food products.
Following a public consultation, the government's Committee on Safety of Medicines (CSM)and the Medicines Commission both concluded that there is clearevidence linking kava with rare cases of liver toxicity. The MCA said it isaware of 70 world-wide reports of adverse liver reactions. In four of thesecases the patients died and in seven cases the patients required livertransplants. There have been four reports of liver toxicity in the UKthought to be due to consumption of the herb.
It added that investigations have been unable to identify factors that would predictwhich individuals are at risk of adverse reactions to kava and themechanism of liver toxicity related to kava remains unknown. The CSMand Medicines Commission were not reassured that the risk of liver toxicitycould be reduced by measures such as label warnings.
The Medicines Control Agency monitors the safety of all herbalmedicines including unlicensed herbal remedies used in the UK using thesame methods as used for conventional medicines. Other conventional or traditional medicines havebeen removed from the UK market over the last twenty years where evidenceof rare but serious liver toxicity has emerged - for example, theanti-diabetic agent Troglitazone, withdrawn in 1997.
Professor Alasdair Breckenridge, chairman of the CSM, said: "Given the expert advice from the CSM and Medicines Commission followingthe recent public consultation it is clear that this ban is necessary.
"Kava-kava has been under investigation for 12 months as new evidence hasgradually emerged and we are grateful to the herbal sector for itsvoluntary withdrawal of Kava-kava products back in December last year.
"The issues surrounding today's decision have been very carefullyconsidered. A prohibition on safety grounds can be reviewed at any time ifnew evidence emerges and the MCA will be undertaking a specific review intwo years time to assess whether this ban remains justified."
Dr Liz Williamson, herbals expert from the London School of Pharmacy, said: "The liver toxicity associated with Kava-kava, although rare, isidiosyncratic. Because of the limited data available a risk to benefitassessment, which is routinely completed for all licensed medicines, is notpossible. No specific risk factors have been identified and it is notpossible to predict who is at risk before they use Kava-kava.
"In addition, no measures to reduce the risk, or the severity of liverreactions, are available. It is therefore in the best interests of patientsthat the herb be withdrawn at present. There are other useful herbal products which can be used for stress andrelated disorders," she added.
Other countries have also taken action over kava products. In the EUall licensed kava products have been removed from the market while inCanada, investigations have concluded that there is insufficient evidenceto support the products' safety and they have also been withdrawn from themarket. In Australia products have been voluntarily removed from the marketwhile an investigation is conducted and in the USA consumers have beenwarned of the risk of liver toxicity pending the outcome of aninvestigation by the FDA.
The herbal ingredient kava is derived from the plant Piper methysticum, a member of the pepper family native to the South Pacific islands.