Fears of impaired mental function and drug dependency act as major deterrents in the use of oral analgesics. The result is a renewed interest in the use of topical application of nonsteroidal anti-inflammatory drugs, opioids, capsaicin, local anesthetics, and alpha-adrenoceptor agonists, which are all being investigated and used for varied pain conditions. Additionally, preclinical studies offer scientific evidence supporting the development of new topical formulations of agents typically taken orally. Combined, these findings offer new options for patients who seek pain relief, but who do not wish to experience significant systemic absorption and risk drug-drug interactions. These risks are particularly apparent in the treatment of elderly patients, who may be fearful of falls or who may be taking multiple medications.
This issue of Advanced Studies in Medicine is based on the proceedings of the 22nd Annual Scientific Meeting of the American Pain Society (APS) in Chicago, Illinois, March 20-23, 2003. Recent clinical evidence surrounding the use of clinically approved and experimental topical analgesics and summary information related to transdermal therapies, applied with patches on the skin but absorbed systemically to achieve therapeutic drug serum levels, are presented.
Gary McCleane, MD, from the Rampark Pain Centre, Lurgan, N Ireland, summarizes the medical literature surrounding the topical use of nitrates, capsaicin, and tricyclic antidepressants for pain management. Jana Sawynok, PhD, an internationally recognized researcher who has published extensively in the area of biochemical and pathophysiologic mechanisms of pain, presents an overview article of recent clinical findings surrounding the topical use of tricyclic antidepressants to achieve analgesic effects. Dr Sawynok also offers a comprehensive review of medical evidence surrounding the full range of topical agents.
Charles E. Argoff, MD, from North Shore University Hospital, and New York University, discusses the adjunctive role of topical analgesics, including topical formulations of opiates, in pain management. He presents recent clinical evidence suggesting that topical analgesics, which are typically viewed as acting on peripheral pain mechanisms, also may play a role in the central processing of pain. He reports on a series of clinical studies demonstrating novel applications of topical agents in centrally mediated pain, including osteoarthritis.
Also included within this issue are summaries of selected poster presentations from the APS meeting, as well as abstracts of recent articles from the medical literature. The combined medical evidence reported in this publication suggests new options for clinicians faced with the challenge of treating the 50 million Americans who have chronic pain. Topical agents, used alone or in combination with other therapies, are proving to be both safe and effective in reducing pain and improving function in patients with a variety of neuropathic and nonneuropathic pain states.
*Professor, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.