Can natural remedies containing St Johns wort or valerian extract interact with Lithionit (lithium)

Fråga: Can natural remedies containing St Johns wort or valerian extract interact with Lithionit (lithium) or Lamictal (lamotrigine)?

A 17-year-old man is treated with lithium and lamotrigine (doses unknown) for manic psychosis and epilepsy, respectively. The patient´s diseases have been well controlled for many years. About a year ago he suffered from a grand mal seizure. The mother suspects that he uses natural remedies containing St Johns wort or valerian.

Sammanfattning: No drug interactions between valerian or St Johns wort and lamotrigine or lithium are documented in the literature, even though St Johns wort is known to induce several drug metabolising enzymes and thereby cause a lack of drug effect. A few cases of untoward mood disorders have been reported for both valerian and St Johns wort. It is not possible to conclude whether these natural remedies could have contributed to the patient´s grand mal seizure.

Svar: There are no documented drug interactions between valerian or St Johns wort and lamotrigine or lithium in available literature.

Lithium is almost completely excreted unchanged by the kidneys and lamotrigine is metabolised by glucuronidation (1). It has been demonstrated that some alkaloids in St Johns wort (i.e. hypericum) can induce many drug metabolising enzymes belonging to the cytochrome family (2, 3). However, we found no indications in the literature, that St Johns wort also induces glucuronosyltransferases. Therefore, a metabolic drug interaction between St Johns wort and lamotrigin is less likely.

There is no obvious theoretical reason to suspect a pharmacodynamic drug interaction between valerian or St Johns wort and lithium or lamotrigine. A few cases of untoward mood disorders (mania, hallucination, obsessions, affective disorders and other personality disorders) have been reported as side-effects for both valerian and St Johns wort (4-7). Therefore, valerian and St Johns wort is perhaps better avoided in this patient. However, it is not possible to conclude whether intake of these herbal drugs could have contributed to the patient´s grand mal seizure. 1 FASS 2002 (The Swedish catalogue of approved medical products) 2 Sjöqvist F. Interaktion mellan läkemedel. In: FASS 2002 (The Swedish catalogue of approved medical products). p. 1481-1556. 3 Henderson L., Yue QY, Bergquist C, Gerden B, Arlett P. St John´s wort (Hypericum perforatum): drug interactions and clinical outcomes. Br J Clin Pharmacol 2002;54 :349-56.

4 Swedis (The Swedish Drug Information System) (cited 2003-02-11)
5 Nierenberg AA, Burt T, Matthews J, Weiss AP. Mania associated with St. John´s wort. Bio Psychiatry 1999;46:1707-8.
6 Aronson JK, editor. Side effects of drugs. Annual 23. Amsterdam: Elsevier; 2000. p. 508.

7 Intdis (International Drug Information System): WHO:s adverse drug reactions database (cited 2003-03-14)