Unrelieved pain is a major global healthcare problem. There are two types of pain: acute pain, which is typical after surgery and trauma and chronic or recurring pain, which is common in individuals suffering from osteo- and rheumatoid arthritis, those with spine problems, and can be developed after operations and injuries. The problem is so great that chronic and recurrent pain is regarded as a disease in its own right. Apart from the burden of suffering, chronic pain results in a considerable cost to society that is on a par with cancer or cardiovascular disease by affecting one in five adults.
Opioids are the analgesics most prescribed to treat moderate to severe pain but their use leads to a number of debilitating side effects, diminishing efficacy, and also the risk of abuse and misuse. A research team at Université de Sherbrooke in Canada has investigated combining the prototypical opioid morphine and an analgesic neurotensin brain-penetrant peptide analog to treat pain. They discovered that co-administration resulted in an additive analgesic response that permitted the dosing of morphine to be reduced and also decreased the level of a typical adverse side effect, constipation.