Feverfew
Car Pharm J 122:266-70, 1989).
Feverfew appears to work in the treatment and prevention of migraine headaches by inhibiting the release of blood vessel dilating substances from platelets (serotonin and histamine), inhibiting the production of inflammatory substances (leukotrienes, serine proteases, etc.), and re-establishing proper blood vessel tone. Commercial sources providing assurance of botanical identity and minimum required level of parthenolides are needed
Extract of feverfew inhibits prostaglandin biosynthesis. Letter.
Lancet October 25, 1980).
In vitro Study: Feverfew was found to contain a factor that inhibits prostaglandin synthesis, but differs from salicylates by not inhibiting cyclo-oxygenase by prostaglandin (PG) synthase. "The ability of feverfew to inhibit PG production may account for its effectiveness as a herbal remedy in conditions responding to acetylsalicylate and like-acting drugs"
Feverfew and vascular smooth muscle: Extracts from fresh and dried plants show opposing pharmacological profiles, dependent upon sesquiterpene lactone content.
Planta Medica 59:20-5, 1993).
The dosage of feverfew used in one double-blind study was one capsule containing 25 mg of the freeze-dried pulverized leaves twice daily; in another double-blind study it was one capsule containing 82 mg of dried powdered leaves once daily. While these low dosages may be effective in preventing an attack, a higher dose (I to 2 grams) may be necessary during an acute attack. Note: The efficacy of feverfew is dependent upon adequate levels of parthenolide, the active ingredient. (The preparations used in successful clinical trials have a parthenolide content of 0.4-0.66%.) Animal Ex vivo Study: Extracts of fresh feverfew caused a dose- and time dependent, irreversible inhibition of the contractile response of rabbit aortic rings to all receptor-acting agonists tested. The presence of potentially SH reacting parthenolide and other sesquiterpene alpha-methylenebutyrolactones in, these extracts, and the close parallelism of pure parthenolide, suggest that the inhibitory effects are due to these compounds. Extracts of the dry leaves were not inhibitory and actually caused potent and sustained contractions of aortic smooth muscle; these extracts were found to be devoid or parthenolide or butyrolactones
Estimation of commercial and authenticated feverfew products.
J Pharm Pharmaco1 44:391-5, 1992).
Chemical Analysis: The parthenolide content of over 35 different commercial preparations of feverfew was determined by bioassay, 2 HPLC methods, and NMR. The results indicate a wide variation in the amts. of parthenolide in commercial preparations. The majority of products contained no parthenolide or only traces (Heptinstall S et al. Parthenolide content and bioactivity of feverfew (Tanacetum parthenium (L.)
