Anti-inflammatory agents for the treatment of musculoskeletal pain and arthritis

Circadian pattern of spontaneous behavior in monarthritic rats: a novel global approach to evaluation of chronic pain and treatment effectiveness

OBJECTIVE

Preclinical evaluation is an essential step in the assessment of new antiinflammatory or analgesic drugs. This study was undertaken to develop a new mode of evaluation of drug effectiveness based on behavior indicating well-being in a rat model of chronic inflammatory pain. We chose to examine the circadian pattern of spontaneous behavior.

METHODS

The work was performed with a model of chronic monarthritis induced by Freund's complete adjuvant. Variations in behavioral patterns during the time course of arthritis were analyzed. In a second phase, the impact of acetaminophen and 2 nonsteroidal antiinflammatory drugs (aspirin and celecoxib), which are currently used in clinical practice to treat chronic inflammation, was studied after 7 days of treatment.

RESULTS

The nocturnal pattern of activity of healthy rats comprised 3 main bursts. Chronic painful monarthritis altered this spontaneous pattern of nocturnal behavior (normal period of activity). Monarthritic rats showed a decrease in the total time spent in activity during the night, and lost their pattern of activity. These behavioral disturbances were reversed after long-term treatment with acetaminophen or celecoxib, with celecoxib appearing to be more effective. Aspirin was ineffective.

CONCLUSION

These results enabled us to test this new procedure as a means of assessing well-being or ill- being during stages of chronic inflammatory pain in rats, and the effectiveness of repeated pharmacologic treatments.

Ginger--an herbal medicinal product with broad anti-inflammatory actions

The anti-inflammatory properties of ginger have been known and valued for centuries. During the past 25 years, many laboratories have provided scientific support for the long-held belief that ginger contains constituents with antiinflammatory properties. The original discovery of ginger's inhibitory effects on prostaglandin biosynthesis in the early 1970s has been repeatedly confirmed. This discovery identified ginger as an herbal medicinal product that shares pharmacological properties with non-steroidal anti-inflammatory drugs. Ginger suppresses prostaglandin synthesis through inhibition of cyclooxygenase-1 and cyclooxygenase-2. An important extension of this early work was the observation that ginger also suppresses leukotriene biosynthesis by inhibiting 5-lipoxygenase. This pharmacological property distinguishes ginger from nonsteroidal anti-inflammatory drugs. This discovery preceded the observation that dual inhibitors of cyclooxygenase and 5-lipoxygenase may have a better therapeutic profile and have fewer side effects than non-steroidal anti-inflammatory drugs. The characterization of the pharmacological properties of ginger entered a new phase with the discovery that a ginger extract (EV.EXT.77) derived from Zingiber officinale (family Zingiberaceae) and Alpina galanga (family Zingiberaceae) inhibits the induction of several genes involved in the inflammatory response. These include genes encoding cytokines, chemokines, and the inducible enzyme cyclooxygenase-2. This discovery provided the first evidence that ginger modulates biochemical pathways activated in chronic inflammation. Identification of the molecular targets of individual ginger constituents provides an opportunity to optimize and standardize ginger products with respect to their effects on specific biomarkers of inflammation. Such preparations will be useful for studies in experimental animals and humans.