Abstract
Timely discussion of herbal treatments and our attitudes toward them appeared in the August 1999 issue of the Journal. Both the lead article by Walter and Rey [1] and the commentary by Boyce [2] argue that we need to know about such treatments for the simple reason that many of our patients take (or are considering) them and may seek our advice. By contrast, Bergen (Chair of the RANZCP Committee on Psychotropic Drugs and other Physical Treatments) argues that herbal remedies should not be part of medical curricula or postgraduate training in psychiatry [3].
To my mind, the crucial issues come into sharpest relief with regard to Hypericum perforatum (St John's wort, SJW), a widely used, over-the-counter antidepressant. In this case, there is Cochrane-proven efficacy in mild to moderate depression, and side-effects which are generally similar to, if anything milder than, those of the SSRIs [4]. Saint John's wort produces far less sexual dysfunction than the SSRIs, but rarely may cause a photosensitivity reaction. Interestingly, SJW appears to act like an SSRI in terms of possible pharmacodynamic interaction with monoamine oxidase inhibitors (MAOIs), and (like most antidepressants) may provoke mania in those with a bipolar tendency. In my experience, SJW is also effective in moderate to severe depression, but this often requires careful titration above the usual dose.
Significant illnesses such as major depression are best treated by a competent doctor, irrespective of whether the treatment is conventional.
As with any active treatment, it is important that appropriate cautions are given, in the case of SJW, for example, with regard to ingestion during pregnancy or in combination with MAOIs. Recently, SJW has been found to reduce the availability of a number of drugs (notably including protease inhibitors, immunosuppressants and warfarin) by inducing hepatic drug metabolism [5].
All is not well in the present state of herbal practice in Australasia. A number of compounds have, at best, equivocal evidence of efficacy, and are probably not worth the cost, trouble or risk of adverse effects. With respect to those products such as SJW, which do have a favourable risk–benefit ratio, there is generally the need for further research into efficacy and safety in defined clinical populations [4]. It is also an urgent priority that such herb sources and extracts be regulated and better standardised, as occurs in Germany, where SJW is medically prescribed and substantially outsells fluoxetine [6].
How the regulatory agencies in Australia and New Zealand deal with quality control will be worth watching, and College input into the process an option to consider. The complexity of this issue is underscored by the fact that such standardisation as does occur is generally done with respect to the hypericin content of SJW extracts. Hypericins are weak inhibitors of monoamine oxidase type A (MAO-A), but now appear to be less important to antidepressant action than other constituents of the herb, notably hyperforin [7]. Consistent with the clinical profile of SJW, hyperforin enhances the synaptic availability of serotonin, as well as dopamine and noradrenaline [7]. Hypericins and hyperforin also differ in their relative abundance across the growth cycle of the herb, the latter being far more abundant as the flowers wilt [8].
The unfortunate conclusion is that current standardisation (with respect to hypericins) may not correlate with clinical potency (more likely due to hyperforin). This may explain the inconsistent results seen in some clinical trials, and indicates the importance of further research and the urgent need for better standardisation.
Herbal remedies pose a real challenge to psychiatry. Given the availability of useful agents such as SJW and their widespread use in Australasia, I believe psychiatrists require an up-to-date working knowledge of such treatments, otherwise we run the risk of being sidelined or ignored by patients who could otherwise benefit from our input. Patients who seek our help are entitled to an unbiased summary of the evidence available, together with expert management of mental disorder, regardless of whether the chosen treatment is conventional.