Mahonia ointment in the treatment of psoriasis
Oregon grape (Mahonia aquifolium (Pursh) Nutt., Berberidaceae)
is frequently cited in traditional herbal literature as an effective
treatment for psoriasis vulgaris, a proliferative skin disorder of uncertain
etiology. The chronic nature of psoriasis generally necessitates long-term
treatment, and standard therapeutic agents are often associated with
safety concerns.
Topical ointments containing Mahonia bark extract are now marketed
in Europe for psoriasis. Results of recent in vitro trials utilizing
human keratinocytes suggest that Oregon grape bark extract as well as
the consitutents berberine, berbamine, and oxycanthine have antiproliferative,
antioxidant and antiinflammatory effects relevant to psoriasis.
Based on this evidence and their own unpublished preliminary findings,
these German investigators designed a randomized placebo-controlled
study to evaluate the efficacy of an ointment containing 10% Mahonia
bark extract in psoriasis of all severity gradings (mild to severe).
Eighty-two patients with psoriasis were instructed to apply the Mahonia
and placebo ointments two or three times a day, one ointment on
the right side of the body and the other on the left, and to wear ointment-soaked
bandages at night. Body sides were randomly assigned to Mahonia
ointment or placebo, which consisted of the ointment base. According
to the authors, their chosen trial design is standard in dermatology
research.
Average length of treatment was four weeks, after which physicians and
patients assessed treatment efficacy utilizing a three-step scale: "symptoms
unchanged," "symptoms improved", and "symptoms disappeared
completely." Based on patient efficacy assessments, there were
some statistically significant differences between the Mahonia
and placebo ointments, but overall, more than half of both patients
and physicians judged the Mahonia ointment as ineffective. Among
treatment responders, Mahonia was particularly effective in moderately
severe psoriasis, and the investigators concluded that Mahonia
bark ointment is "a potent and safe therapy of moderately severe
cases of psoriasis vulgaris." Side effects, including itching,
burning, and allergic reactions, were reported by four patients.
Study shortcomings cited by the authors include unspecific inclusion
criteria (allowing inclusion of extremely severe and long-standing cases
of psoriasis), a "crude" main effect measurement scale that
might not be sensitive to small changes, and possible patient errors,
such as confusion about the assignment of body sides and failure to
adequately wash hands between applications of the two ointments. The
relatively "high number" of treatment nonresponders was attributed
to the inclusion of extremely severe cases of psoriasis.
-- Evelyn Leigh, HRF
[Wiesenauer, M., and Ludtke,
R. 1996. Mahonia aquifolium in patients with Psoriasis vulgaris
-- an intraindividual study. Phytomedicine, Vol. 3, 231-235.]
[Muller, K., Ziereis, K., Gawlik, I. 1995. The antipsoriatic Mahonia
aquifolium and its active constituents; II. Antiproliferative activity
against cell growth of human keratinocytes. Planta Med, Vol. 61,
74-75.] |
