From Bush Medicine to Modern Phytopharmaceutical: A Bibliographic Review of Devil's Claw (Harpagophytum spp.)

Devil's claw (Harpagophytum spp., Pedaliaceae) is one of the best-documented phytomedicines. Its mode of action is largely elucidated, and its efficacy and excellent safety profile have been demonstrated in a long list of clinical investigations. The author conducted a bibliographic review which not only included peer-reviewed papers published in scientific journals but also a vast amount of grey literature, such as theses and reports initiated by governmental as well as non-governmental organizations, thus allowing for a more holistic presentation of the available evidence. Close to 700 sources published over the course of two centuries were identified, confirmed, and cataloged. The purpose of the review is three-fold: to trace the historical milestones in devil's claw becoming a modern herbal medicine, to point out gaps in the seemingly all-encompassing body of research, and to provide the reader with a reliable and comprehensive bibliography. The review covers aspects of ethnobotany, taxonomy, history of product development and commercialization, chemistry, pharmacology, toxicology, as well as clinical efficacy and safety. It is concluded that three areas stand out in need of further investigation. The taxonomical assessment of the genus is outdated and lacking. A revision is needed to account for intra- and inter-specific, geographical, and chemo-taxonomical variation, including variation in composition. Further research is needed to conclusively elucidate the active compound(s). Confounded by early substitution, intermixture, and blending, it has yet to be demonstrated beyond a reasonable doubt that both (or all) Harpagophytum spp. are equally (and interchangeably) safe and efficacious in clinical practice.

Devil's Claw (Harpagophytum procumbens) as a treatment for osteoarthritis: a review of efficacy and safety

BACKGROUND

Osteoarthritis (OA) is a highly prevalent musculoskeletal disorder. Conventional treatment (i.e., the use of nonsteroidal anti-inflammatory drugs-NSAIDs) is associated with well-documented adverse effects. Devil's Claw (Harpagophytum procumbens) a traditional South African herbal remedy used for rheumatic conditions, may be a safer treatment option. To date, 14 clinical trials have assessed its efficacy/ effectiveness in OA.

AIM

To address the two main questions of importance to clinicians: (1) Does Devil's Claw work for the treatment of OA, and (2) Is it safe?

METHODS

A review of the literature on Devil's Claw and OA from 1966 to 2006 was performed using multiple search databases, monographs, and citation tracking. Relevant trials in all languages were identified and included. Both internal validity (i.e., adequacy of the dosage and period of treatment for this condition, reporting of randomization, rates of dropout, blinding, and statistical analysis) and external validity (i.e., inclusion/ exclusion criteria, baseline characteristics of the study populations, trial setting, and the appropriateness of the outcome measures of the trials) were assessed.

RESULTS

Fourteen studies were identified: eight observational studies; 2 comparator trials (1 open, the other randomized to assess clinical effectiveness); and 4 double-blinded, placebo-controlled, randomized controlled trials to assess efficacy. Many of the published trials lacked certain important methodological quality criteria. However, the data from the higher quality studies suggest that Devil's Claw appeared effective in the reduction of the main clinical symptom of pain. The assessment of safety is limited by the small populations generally evaluated in the clinical studies. From the current data, Devil's Claw appears to be associated with minor risk (relative to NSAIDs), but further long-term assessment is required.

CONCLUSIONS

The methodological quality of the existing clinical trials is generally poor, and although they provide some support, there are a considerable number of methodologic caveats that make further clinical investigations warranted. The clinical evidence to date cannot provide a definitive answer to the two questions posed: (1) Does it work? And (2) is it safe? A definitive high-quality trial that addresses the necessary methodologic improvements noted is needed to answer these important clinical questions.

Evidence of effectiveness of herbal antiinflammatory drugs in the treatment of painful osteoarthritis and chronic low back pain

Treatment with herbal medicines is very popular in Europe. In order to get information on the evidence of effectiveness of oral herbal medicines in the treatment of pain in the joints or lower back, OVID(MEDLINE), PUBMED and COCHRANE COLLABORATION LIBRARY were searched back to 1985 for systematic reviews. The level of evidence of effectiveness was defined as strong - at least two confirmatory studies demonstrating a clinical relevant effect, moderate - one confirmatory study with a clinical relevant effect and/or multiple exploratory studies of good quality; otherwise the evidence was insufficient or conflicting in the case of inconsistent findings. Fifteen systematic reviews were identified. The evidence of effectiveness was strong for a proprietary unsaponifiable avocado soybean fraction and Harpagophytum preparations containing > 50 mg harpagoside in the daily dosage, moderate for ginger and a proprietary rose hip and seed powder, insufficient for Boswellia serrata gum resin and other herbal preparations and inconsistent for a proprietary willow bark extract. Further rigorous studies are required to confirm the usefulness of herbal medicines in the treatment of osteoarthritic complaints and chronic low back pain in order to enable acceptance of the herbal medicines into the treatment guidelines.

Liquid chromatography/electrospray ionization mass spectrometric characterization of Harpagophytum in equine urine and plasma

A method has been developed for the analysis and characterization in equine urine and plasma of iridoid glycosides: harpagide, harpagoside and 8-para-coumaroyl harpagide, which are the main active principles of Harpagophytum, a plant with antiinflammatory properties. The method involves liquid chromatography coupled with positive electrospray ionization mass spectrometry. The addition of sodium or lithium chloride instead of formic acid in the eluting solvent has been studied in order to enhance the signal and to modify the ion's internal energy. Fragmentation pathways and associated patterns are proposed for each analyte. A comparison of three types of mass spectrometer: a 3D ion trap, a triple quadrupole and a linear ion trap, has been conducted. The 3D ion trap was selected for drug screening analysis whereas the linear ion trap was retained for identification and quantitation analysis.