Breakthrough Pain-Novel Analgesics

Breakthrough pain (BTP) is a transitory exacerbation of pain that occurs on a background of otherwise controlled pain. It is associated in conjunction with severe chronic pain and may result in impaired physical and psychological functioning, reduced effectiveness to opioids and also, increased financial burden. It manifests commonly in malignant pain, as manifested by well managed round the clock regular opioid medication but associated with intermittent sharp pain symptoms that are not controlled by the regular medication. It is a significant clinical problem and should be independently assessed and treated. The most common approach being used is 'rescue' medication--a short acting opioid in combination with the fixed-schedule opioid regimen. The lag time between peak pain intensity during an episode of BPT and onset of analgesia of most short-acting opioids is approximately 30-60 minutes. This suggests that the effectiveness of supplemental medications for BTP might be improved with analgesic agents that have a more rapid onset of action. Traditionally the rapid onset analgesia for breakthrough pain has been achieved by administering potent opioids through sublingual route bypassing the first pass metabolism. However with recent advances in drug delivery systems, transmucosal and buccal routes have gained popularity. Pharmacokinetic studies have demonstrated a high early systemic exposure to opioids well over their therapeutic dose range resulting in management of the breakthrough pain. This article proposes to review the evidence base on the effectiveness of these novel opioid delivery systems in managing the breakthrough pain.