Herb-Drug Interactions: Frangula

Rhamnus frangula L. (Rhamnaceae)

Synonym(s) and related species

Alder buckthorn.

Frangula alnus Mill, Frangula nigra Samp, Rhamnus cathartica L.

Pharmacopoeias

Frangula Bark (British Ph 2009, European Ph 2008); Standardised Frangula Bark Dry Extract (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4).

Constituents

The major constituents of frangula are the anthraquinone glycosides. The frangulosides are the main components, which include franguhn A and B, emodin derivatives, chrysophanol and physcion glycosides, and free aglycones. Frangula also contains flavonoids and tannins.

Use and indications

Frangula bark is used as a laxative.

Pharmacokinetics

For information on the pharmacokinetics of an anthraquinone glycoside present in frangula, see under aloes.

Interactions overview

No interactions with frangula found; however, frangula (by virtue of its anthraquinone content) is expected to share some of the interactions of a number of other anthraquinone-containing laxatives, such as aloes and senna9. Of particular relevance are the interactions with corticosteroids, digitalis glycosides and potassium-depleting diuretics.