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Letters to the Editor
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St John's wort
Is it time for St John's wort to become a pharmacy medicine?
From Dr R. J. Schmidt, MRPharmS
As any student of pharmacognosy (from those schools of pharmacy where
the subject has been taught in recent years) will attest, there is nothing
new in the revelation that a given herbal product from a variety of commercial
sources is likely to vary in its composition and is also more likely
than not to fail to contain what its label claims it does. The findings
of Wang et al (as elaborated upon in the PJ, 14 February, p174) concerning
five commercial St John’s wort products are therefore unremarkable.
It is not widely appreciated that in the UK, “herbal medicine” broke
away from what we now call “allopathic medicine” at about
the time of the first appearance of the British Pharmacopoeia in 1864,
which arose out of the Medical Act 1858.
Herbal medical practitioners refused to be constrained by the need for
their products to comply with the quality standards imposed by a pharmacopoiea.
It took another Act of Parliament — the Medicines Act 1968 — to
force the issue of compliance with published quality standards, this
leading to the publication of the first British Herbal Pharmacopoiea.
But many, if not most, manufacturers of herbal products continue to evade
the issue of compliance with an appropriate quality standard.
Pharmacists in the UK are obliged to comply with the standards of practice
laid down in ‘Medicines, ethics and practice — a guide for
pharmacists’. These guidelines require that pharmacists do not
sell or supply herbal medicines where there is a reason to doubt their
safety or quality. It follows that pharmacists should now cease to supply
St John’s wort unless a manufacturer can guarantee that its product
does in fact contain an effective and specified dose of the active material.
Is there a manufacturer out there who can do such a thing?
But what is the active material in St John’s wort? Wang et al1 clearly believe that hypericin and pseudohypericin are the antidepressant
substances. They have obviously not read the excellent review paper published
by Barnes et al2 in 2001, in which the antidepressant activity is ascribed
to the chemically unrelated hyperforin rather than to the hypericins.
Barnes et al, in turn, refer to studies originally published in 1998
by Chatterjee et al3,4 and by Laakmann et
al.5 So, if hyperforin is the
active antidepressant agent, where does that leave community pharmacists
with stock of ill-defined St John’s wort on their shelves?
Given the incidence and clinical relevance of interactions and side effects
of St John’s wort, there have been calls in the literature for
St John’s wort to be upgraded to a pharmacy-medicine.6 Perhaps
the regulatory authorities should now act.
Richard Schmidt
Barnoldswick, Lancashire
References
1. Wang Z-K, Lin S-M, Hu M-L. Contents of hypericin and pseudohypericin
in five commercial products of St John’s wort (Hypericum perforatum).
Journal of the Science of Food and Agriculture 2004; in press (early
view abstract published online
2. Barnes J, Anderson LA, Phillipson JD. St John’s wort (Hypericum
perforatum L.): a review of its chemistry, pharmacology and clinical
properties. Journal
of Pharmacy and Pharmacology 2001;53:583–600.
3. Chatterjee SS, Bhattacharya SK, Wonnemann M, Singer A, Muller WE.
Hyperforin as a possible antidepressant component of hypericum extracts.
Life Sciences 1998;63:499–510.
4. Chatterjee SS, Noldner M, Koch E, Erdelmeier C. Antidepressant activity
of Hypericum perforatum and hyperforin: the neglected possibility. Pharmacopsychiatry 1998;31(Suppl):7–15.
5. Laakmann G, Schüle C, Baghai T, Kieser M. St John’s wort
in mild to moderate depression: the relevance of hyperforin for the clinical
efficacy. Pharmacopsychiatry 1998;31(Suppl):54–9.
6. Schulz V. Incidence and clinical relevance of the interactions and
side effects of Hypericum preparations. Phytomedicine — International Journal of Phytotherapy and Phytopharmacology 2001;8:152–60. |
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