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Cat's claw for arthritis.

History and Rationale for Use

In the medicinal system of the Ashaninka Indians of Peru, the human being is made up of body and spirit--flesh (ivatsa) and "deepest being" (isancane). As with many traditional systems, health is considered to be a state of harmony, with the literal translation of the phrase "I am healthy (nocaratanaje)" being "I carry harmony," according to Klaus Keplinger, who during nine trips to the Amazon rain forest (J. Ethnopharmacol. 1999;64: 23-34).

According to the Ashaninka, disruptions in communication between body and spirit are a result of anxiety, and preparations of powerful plants (saventaro) that are inhabited by good spirits can eliminate these disruptions and restore health and harmony. One of these plants is Uncaria tomentosa, or una de gato (cat's claw), so called because of its distinctive curling hooks. A decoction of sliced root bark boiled in water is used in traditional Peruvian medicine to treat numerous inflammatory disorders, ulcers, and infections.

Mechanisms of Action

Various hypotheses have been proposed to account for the purported clinical effects of cat's claw. One group of investigators has reported that the most likely mechanism for cat's claw's effects is immunomodulation via suppression of tumor necrosis factor-[alpha] (TNF-[alpha]) synthesis. The in vitro suppression ranges from 65% to 85%, which they described as "not a drawback," because "complete inhibition of TNF-[alpha] and other inflammatory/immune mediators may result in a dangerous state of immune suppression, leaving the host vulnerable to invading microorganisms and tumor development. This fear [has been] borne out with anti-TNF-[alpha] therapy where the incidence of lymphomas is increasing" (Free Radic. Biol. Med. 2000;29:71-8).

Another group of researchers recently proposed that cat's claw's effects also derive from enhancement of DNA repair and immune cell responses through regulation of the nuclear transcription factor-[beta] (NF-[beta]), which controls nuclear events that protect the cell from apoptosis and also controls proinflammatory cytokine production (J. Ethnopharmacol. 2005;96:577-84).

In vitro studies also have identified free radical scavenging activity and inhibition of prostaglandin [E.sub.2] ([PGE.sub.2]) production.

The active principles thought to be responsible for these effects are pentacyclic oxindole alkaloids (POA). Two chemotypes of U. tomentosa exist; only the POA chemotype is immunomodulating. The second chemotype contains tetracyclic oxindole alkaloids that inhibit the immunomodulating effects (Planta Med. 1998;64:701-4).

Clinical Studies

A double-blind trial of an extract from U. tomentosa (Krallendorn capsules, made by Immodal Pharmaka GmbH, Volders, Austria) was recently conducted among a group of 40 patients with rheumatoid arthritis being treated at Innsbruck (Austria) University Hospital.

All patients had active disease and had been treated with sulfasalazine or hydroxychloroquine for at least 6 months. Nonsteroidal anti-inflammatory drugs and prednisolone up to 10 mg/day were permitted during the study.

Patients were randomized to receive one capsule (20 mg) of the plant extract or placebo three times per day for 24 weeks. During the next 24 weeks, all patients received the plant extract.

At the end of the first phase of the study, the number of painful joints had decreased by 53.2% in the active-extract group, compared with 24.1% in the placebo group (J. Rheumatol. 2002;29:678-81). Significant differences also were seen in the number of tender joints and duration of morning stiffness in the treatment group, but not in the placebo group, at 24 weeks compared with baseline.

No changes were seen in other parameters of efficacy, including patient assessment of disease activity, subjective assessment of pain, and laboratory markers, except for an increase in rheumatoid factor in the placebo group.

By the end of the second phase of the study, further significant improvements in the number of tender joints and duration of morning stiffness were seen among patients initially randomized to the extract group. Patients initially randomized to placebo also experienced significant improvements in the number of painful and swollen joints once they were switched to the active extract. These patients also reported decreased pain intensity, disease activity, and duration of morning stiffness, although these differences did not reach statistical significance. There was a nonsignificant decrease in rheumatoid factor in this group.

One patient in the extract group withdrew because of gastritis, and one patient in the placebo group withdrew because of diarrhea. No serious side effects were reported.

Cat's claw has also been evaluated for use in knee osteoarthritis. In a multicenter double-blind study, 45 men were randomized to receive 100 mg of freeze-dried cat's claw or placebo daily for 4 weeks. The cat's claw group experienced significant improvements in pain associated with activity and in patient and physician assessment of disease activity. Improvements were seen as early as week 1 and continued throughout the trial (Inflamm. Res. 2001;50:442-8).

The authors observed a reduction in [PGE.sub.2] production, which they attributed to an inhibition of cyclooxygenase-2 expression. They wrote, "Of particular interest in the treatment of arthritis is the ability of cat's claw to not only confer benefit to the joints but also negate the side effects of NSAIDs on the stomach and intestine.... This Amazonian botanical not only treats the arthritic disease process but also reduces the toxic side effects of the current standard pharmaceuticals used in the management of arthritis. The concept that botanicals can be used to reduce the toxicity of pharmaceuticals is an intriguing and greatly underexplored area of investigation."

* Peruvian Indians have long used preparations made from the cat's claw vine to treat various maladies.

* Two small clinical studies have suggested that the herb may have benefits in patients with rheumatoid arthritis or osteoarthritis.
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Title Annotation:Alternative Medicine: AN EVIDENCE-BASED APPROACH
Author:Walsh, Nancy
Publication:Family Practice News
Geographic Code:1USA
Date:Jun 15, 2005
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