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THE LANCETNeurology Vol 2 February 2003 http://neurology.thelancet.com 67

The leading edge

NeurologyTHE LANCET

In 1997, Americans spent more than $27 billion onalternative therapies, $5·1 billion of which was spenton herbal medicines. According to the same survey,12·1% of adults in the USA had used a herbal medicinewithin the previous 12 months, compared with 2·5%in 1990. Understandably, many physicians are scepticalof these approaches to treatment, yet more and morepatients are trying out alternative therapies.Neurologists are not exempt from this trend; effectivetreatment for many neurological diseases is lackingand some patients will feel the need to turn to lessconventional alternatives. Although research intoherbal remedies, and alternative therapies in general, isincreasing in line with usage, substantial evidence ofefficacy in most is still lacking. But perhaps mostimportantly, so too are safety data.

On January 13, 2003, the Medicines ControlAgency (MCA) in the UK enforced a ban on kava kava(Piper methysticum) after 70 reports of liver toxicityworldwide. This herbal remedy—used for bladderdiscomfort, anxiety, tension, and restlessness—hadbeen under investigation by the MCA since December2001. The liver toxicity associated with kava kava,although rare, is idiosynchratic. In addition, becausethere are limited data available, a risk to benefitassessment, which is routinely completed for alllicensed medicines, could not be done.

There is increasing recognition that herbalmedicines should be treated with the same caution thatis afforded to conventional drugs with regard to druginteractions and the reporting of adverse events. StJohns Wort, for example, which is used to treatdepression, induces cytochrome P450 enzymes andcan interfere with the metabolism and action of otherdrugs. The extent of the problem of interactionsbetween herbal remedies and conventional drugs is notknown but the Spone Survey (JAMA 2002; 287:337–44) reported that 16% of people in the USA whowere taking prescription drugs were also taking aherbal or supplement preparation. Concerns have alsobeen raised over the composition and purity of herbalremedies. A systematic review published in the Journalof Internal Medicine in August last year reportedcontamination of Chinese herbal medicines with drugs such as corticosteroids, anticonvulsants, andbenzodiazepines.

Legislation and regulation of herbal medicines islacking in most countries. In the USA, for example,herbal remedies are classed as food supplements and

are therefore exempt from the Federal Food, Drug, andCosmetic Act. In the UK, most herbal medicines aresold under the Food Act of 1990, with the exception ofsome traditional remedies that are registered under theMedicines Act (1968). However, some Europeancountries—such as Germany, France, and Sweden—have implemented strategies for the licensing of herbalmedicines. And moves are afoot to bring everyone inEurope into line.

On Nov 21, 2002, the European Parliament voted insupport of a Directive on Traditional Herbal MedicinalProducts, which it hopes to introduce by the end of theyear. The Directive stipulates that all herbal medicinesmust undergo a registration procedure before they canbe legally marketed. Although the provision of efficacyand safety data is not required, manufacturers ofherbal medicines will have to provide evidence of“traditional use” (defined as medicinal use for at least30 years, 10 of which must be within the EuropeanUnion). In addition, manufacturers will be obligated toadhere to many of the regulations that apply to themanufacture of conventional drugs: good manu-facturing practice, quality control, regular reporting ofadverse events to the appropriate authority, andaccurate labelling of product contents.

The Directive has met with a mixed response fromthe herbal medicines sector. Some argue that the rangeof herbal medicines available will be greatly reducedand many independent or small herbal manufacturersand retailers will go out of business. Others, however,welcome the initiative as long overdue. Largemanufacturers of herbal medicines already complywith many of the regulations set out in the directive.Although smaller manufacturers may have to changetheir practices, this will be compensated by access tonon-national markets as a direct result of this pan-European standardisation.

But how important is this to the practisingphysician or neurologist? Regardless of whether herbalremedies—and other alternative therapies—areproved to be efficacious, patients will continue to trythem. As a result, it is essential that patients feelcomfortable discussing the issue of alternativetherapies with their treating physician, who shouldlisten objectively, whatever their own opinions on thesubject. The safety of the patient, which this newlegislation aims to protect, must be the first priority.

The Lancet Neurology

Herbal medicines—primum non nocere