Vol. 5 No. 3 June 1990 Spinal Opioids 137

We must hang together, or we will surely hang separately.

Benjamin Franklin

The increasing use of spinal opioids to con- trol postoperative pain, obstetrical pain, and pain of malignant origin has dramatically changed the practice of pain management. ‘The efficacy and relative safety of this approach has led to its rapid acceptance by patients and physicians alike, and this has led to a substantial increase in the visibility of the anesthesiologist in the role of pain specialist. To put this in per- spective, consider the fact that, prior to 1976, essentially no opioids were administered via the spinal route. Yet in 1990, a mere 14 years later, it is estimated that spinal opioids will be used to manage pain in over 120,000 patients. This rapid transition from basic animal studies to widespread clinical use has no precedent in the history of pain management.

In addition to the direct patient applications of spinal opioids, there have been major ad- vances in our understanding of its scientific un- derpinnings. Our increased understanding OF the role of opiate receptors at the spinal cord level and their powerful effect on small afferent pathways has led to the clinical validation of theoretical concepts regarding the role of spe- cific spinal neurotransmitter syster.ls in modu- lating nociceptive processing. This developing appreciation of the pharmacology of spinal re- ceptors has led to the development of novel re- ceptor-selective opioid and nonopioid agonists and antagonist? for clinical use. This synergy between the basic scientist and clinician has been most gratifying.

Today, some 14 years after the inception of sp~:~l opioids as a viable clinical modality, many questions remaiu to be answered. Some reflect perennial problems, that is the volume and ana- tomic location qf injection, the role of spinal opioids in chronic nonmalignant pain, the ef- fects of spinal opioidb on the second stage of labor, and so on. New I,,sues have appeared,

0 U.S. Cancer Pain Relief Committee, 1_;“90 Published by Elsevier, New York. New York

however, as we continue to learn more about the hows and whys of the action of spinal recep- tor-selective drugs. These increasingly complex and sophisticated questions relate to the physio- chemical characteristics (for instance, lipid solu- bility) of ;pin;lllg Aninisrered drugs, the inter- action of spinally administered local anesthetics and opioids, and the clinical applications of re- ceptors and spinal pain-processing systems with which opioid receptors are not actually associ- ated.

The future of spinally administered drugs belongs both to the basic scientist and the clini- cian. The spinal administration of opioid and nonopioid drugs is a potentially powerful tool to :urther the understz&ing of pain processing and provides new clinical application> in the therajpeutic management 4. F pain and ncmpain- ful syndromes such as spa+:Gty. Hnwcvcr, 6h.z spinal administration of drugs must be ap- proached with extreme caution. The short- term and long-term effects of drtigs adminis- tered via the spina. . . 1 -ute are si_mply not known, and the routine spinal administration of drugs without prior investigation in appropriate ani- mal models must be cor.sidezed a potentially hazardous undere,xking. We look to tk clini- cian to exercise jud;;ment in the spinal adminis- tration of drugs in humans. We encom-age the synergy of basic science and chical medicine that has led to the relief of much pairi during the last decade to continue and produce even greater advances in the next 10 years.

Steven D. Waldman, MD Pain Consortium of Greater Kansas City Leawood, Kansas

Tony L.. Yaksh, PhD Department q Anesthesiology

University of Calijnxia-San Diego La J&z, California

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