Scientific Names: Uncaria guianensis, Uncaria tomentosa
Other Common Names: Una de gato, griffe du chat, samento, saventaro
Overall Safety: 😊
Therapeutic Efficacy and Considerations:
Rheumatoid Arthritis: 😐 Although one study of cat’s claw (U. tomentosa) extract has demonstrated benefit in reducing the number of painful and swollen joints when used in combination with prescription anti-inflammatory therapies, the evidence is insufficient to recommend its general use for this indication. Because of the generally mild adverse event profile, cat’s claw may be an option to consider for individual patients. The recommended dose for rheumatoid arthritis is 20 mg of aqueous U. tomentosa extract three times a day.
Osteoarthritis: 😐 One study of U. guianesis extract noted improvement in pain on activity scores and both physician and patient assessment scores. As with rheumatoid arthritis, a recommendation for general use cannot be made as yet, but individual patients may find benefit with use. The recommended dose for osteoarthritis is 100 mg of tetracyclic oxindole alkaloid-free aqueous extract given once daily.
Note: Although the two studies above were conducted with extracts of different species, in vitro and animal tests seem to indicate that similar activities can be expected from both species. Differences in dosing reflect differences in types of extraction techniques, so following the manufacturer’s listed dosing instructions is recommended.
Chemistry/Pharmacology:
Cat’s claw bark contains an assortment of alkaloids, the major one being rhynchophylline, which may have cardiovascular effects such as dilation of peripheral blood vessels and reducing heart rate. It may also inhibit platelet aggregation and lower cholesterol. Anti-inflammatory effects include inhibition of prostaglandin E2 and tumor necrosis factor-alpha (TNF-alpha). Immunomodulatory effects such as enhanced phagocytosis and lymphocyte activity have also been reported. Effects on DNA repair have stimulated research into possible effects for cancer.
Drug Interactions:
Immunosuppressants, antihypertensives, anticoagulants. A preliminary in vitro study noted that cat’s claw may inhibit CYP450 3A4 – monitor effects of these drugs closely if coadministered.
Contraindications/Precautions:
Use with caution in patients with autoimmune disorders, in transplant and skin graft patients (due to immune stimulating effects), in coagulation disorders (due to possible platelet aggregation inhibition), and during pregnancy and lactation.
Adverse Effects:
Hypotension, headache, vomiting and nausea, mild lymphocytosis, erythrocytosis, constipation, diarrhea, and hyperuricemia.
