Topical Lidocaine and Morphine Gel Use for Malignant Wound Pain.

Abstract

Management of malignant wounds, especially from tumor infiltration, remains challenging especially in low-middle income country where resources, such as opioids, may be limited. Management of such wounds is also compounded by the use of intravenous or oral opioids that often might improve the pain, but result in various side effects. Our pharmacy department helped prepare a topical ointment that contained fixed amounts of both morphine and lidocaine specifically for use in malignant wounds. Ninety milligrams of 2% lidocaine gel was mixed with 80 mgs of oral morphine sulfate in a pestle until the mixture was consistent. Four to eight milliliters, depending on the size of the wound, was applied to a gauze and placed over the wound every 8 hours. Table 1 highlights the use of the ointment in select patients with malignant wound and improvement in pain scores over a 2 week period. About 5–10% of patient with metastatic cancer will go on to develop fungating wound that are often associated with pain as most common symptoms (1, 2). These wound share complex pathophysiological process compounded by the an inflammatory process that is often chronic in nature with stimulation of the skin afferent receptors, compression of the wound bed tissue, erosion of the blood and nerves surrounding the wound, resulting in various symptoms including pain that can often be difficult to manage (3). Even though topical agents have been used for pain management, data on the use of such agents in resource limited settings is non-existent. Compound lidocaine creams/gels have been shown to be safe to use in malignant wound managements. Application can reduce pain caused by the inflammatory process and also during the dressing process. The vasodilatory effects of lidocaine, resulting in increased blood flow, have been shown to help with wound healing (4). Lidocaine, also works by inhibiting the transmission of pain signals by blocking the voltage-gated sodium channels in nerve cells. This prevents the initiation and propagation of pain signals, resulting in pain relief (5). Application of such gels have been shown to offer long term relief, without associated systemic side effects and can also decrease the need and use of systemic opioids (3, 4). Topical morphine application to malignant wounds has also been showing to improve pain scores and quality of life, with fewer side effects and reduced need for systemic opioid therapy (6, 7). Topical morphine is thought to act on the peripheral opioid receptors that play a role in modulation of pain (6). In addition, normal, unaffected tissues contain silent opioid receptors that are activated soon after injury to the tissue. In fact, trauma, and inflammatory processes have been shown to increase the synthesis and transport of opioid receptors from the dorsal root ganglia to the peripheral sensory nerve endings (8). Opioid receptors have been found in skins