[Novel potential uses of thalidomide in the management of pain? A review of the literature].

Thalidomide was introduced as a sedative and antiemetic agent to the European market in the late 1950s. However, it soon became clear that a hitherto unheard-of incidence of severe birth defects was due to the maternal use of thalidomide and the drug was withdrawn from the market. Despite its teratogenesis, thalidomide is currently being rediscovered because of its known spectrum of anticachectic, antiemetic, mildly hypnotic, anxiolytic, anti-inflammatory, antiangiogenic, and analgesic properties. The mechanism of action of thalidomide is probably based on its immunomodulatory effect, namely the suppression of production of tumor necrosis factor alpha and the modulation of interleukins. A striking but not well-known finding is the effectiveness of thalidomide as an analgesic or analgesic adjuvant. During the early era of thalidomide use, the drug was shown to enhance the analgesic efficacy of a combined treatment with acetylsalicylic acid, phenacetin, and caffeine (APC) by testing "normal volunteers, using electrical stimulation of teeth." The combination of thalidomide and APC was superior to other combinations (APC alone, APC and codeine) with respect to both the total analgesic effect and the duration of this analgesic effect. In 1965 thalidomide was found to be effective in treating the painful subcutaneous manifestations of the leprosy-associated erythema nodosum leprosum, a condition for which it eventually was approved by the United States Food and Drug Administration in 1998. In an animal model of neuropathic pain (chronic constriction injury), thalidomide was shown to reduce both mechanical allodynia and thermal hyperalgesia. Recent studies documented the analgesic efficacy of thalidomide in treating painful mucocutaneous aphthous ulcers associated with HIV syndrome and Behcet's disease.However, to date there are no recent clinical trials that are specifically designed to explore the analgesic potential of thalidomide. In view of the current basic research and clinical findings,we suggest to investigate the potential benefits of thalidomide in severe pain conditions that respond poorly to common pain management approaches such as neuropathic pain, postherpetic neuralgia, or central pain phenomena. Because its mechanism of action is distinct from that of other drugs such as steroids, thalidomide offers the possibility of a combined treatment with other agents with nonoverlapping toxicities. We conclude that thalidomide, when used properly,may enrich the therapeutic regimen in the management of some pain-related conditions.