Abstract
Morphine is now said to have no problematic side effects such as analgesic tolerance and physical dependence for cancer pain patients in clinic, as far as it is appropriately used. However, sub-sensitivity to morphine might be developed when higher doses of morphine are used for terminal cancer pain patients. Along with the severity of cancer, the nature of pain becomes changed to neuropathic pain, which is resistant to morphine or NSAIDS. In order to safely use morphine in the clinic, we need to know how morphine tolerance and neuropathic pain are developed and what adjuvants could be used to completely suppress the pain. Here I overview the proposed mechanisms for morphine tolerance and neuropathic pain in relation to the availability of analgesic adjuvants.
