Recent development in therapeutics for breakthrough pain.

Breakthrough pain is defined as transitory flares of pain. Breakthrough pain is caused by cancer, cancer complications, treatment or comorbidities. The usual onset to maximum breakthrough pain intensity time is 3 min and duration is 30 min; therefore, the assessment for response needs to be at short intervals. The rapid onset and offset of pain results in inadequate responses when oral opioids are used to manage pain flares. Several strategies have been used to manage breakthrough pain: titration of the chronic opioid, independent titration of rescue opioids and alternative routes. Buccal fentanyl has a rapid onset to analgesia and appears to be superior to oral morphine. Newer fentanyl preparations have been released to manage breakthrough pain in the opioid-tolerant individual. Other routes of administration that have a rapid onset to analgesia include intranasal hydrophilic and lipophilic opioids, inhaled opioids delivered by special delivery devices and parenteral morphine. In a small series of patients experiencing severe flares of pain with spinal opioids unrelieved by parenteral opioids, sublingual ketamine and bolus doses of intrathecal local anesthetics have been effective. Nonpharmacological approaches to managing activity-related pain include radiation therapy, surgical correction of impending fractures, kyphoplasty and radioisotopes.