The new class of antiinflammatory and analgesic drugs, the selective cyclooxygenase (COX-2) inhibitors, which promise to be devoid of the types of toxicity associated with nonsteroidal antiinflammatory drugs (NSAID), especially adverse gastrointestinal effects, are under clinical trial but are not yet available for use. All NSAID, including those most recently introduced, exhibit nonselectivity of action, producing therapeutic blood levels that inhibit constitutive COX-1 and deplete tissue protective prostaglandins. Among NSAID, the diclofenac/misoprostol combination (Arthrotec) is unique in possessing an active component, misoprostol, to help prevent NSAID induced gastrointestinal damage. Ulcer damage and associated serious complications probably represent only the tip of the iceberg in relation to clinically significant side effects associated with the use of NSAID. In this context, metaanalysis of 8 large multicenter studies reported here has shown that patients taking NSAID show a mean decrease in hemoglobin over 4 - 12 weeks' assessment, with some 10-20% of patients exhibiting clinically significant decreases (> or = 1 g/dl) early in treatment. Patients taking diclofenac/misoprostol showed significantly less of a decline in hemoglobin and up to 50% fewer clinically significant decreases than patients receiving diclofenac alone. The misoprostol component of diclofenac/misoprostol may also help to restore homeostasis in tissues other than the gut. Inhibition of the activity or release of various tissue damaging agents and inflammatory cytokines, e.g., thromboxane and interleukin 1, are described, as are in vivo animal studies that have revealed synergistic or potentiating analgesic and antiinflammatory activities between misoprostol and NSAID, particularly diclofenac. Clinical studies in postsurgical dental pain in more than 500 patients have now shown enhanced analgesia, with greater relief over a longer period, for the diclofenac/misoprostol combination compared with diclofenac alone. The relevance of these findings to pain and inflammation control in arthritis is discussed. Enhanced control of morning stiffness provided by diclofenac/misoprostol, possibly also the result of misoprostol/diclofenac synergy, is also reported, and the development of an objective system that measures 24 hour ambulatory activity is described. Using this Numact recorder, improved mobility in patients receiving diclofenac 75 mg/misoprostol 200 microg was observed compared with patients treated with diclofenac 75 mg slow release. Further studies are being performed employing magnetic resonance imaging both to assess antiinflammatory effects in joint soft tissue architecture and to assess whether the synergistic stimulatory effects of diclofenac and misoprostol on human osteoarthritic cartilage that have been reported in vitro are clinically evident. A growing body of evidence supports the view that the diclofenac/misoprostol combination provides an improved therapeutic ratio over diclofenac alone, not only by improving gastrointestinal safety but also by enhancing analgesic/antiinflammatory effects.