Fentanyl transmucosal tablets: current status in the management of cancer-related breakthrough pain.

Breakthrough pain is a newly recognized pain category that was first described by Portenoy and Hagen in 1990. The term describes pain that increases in intensity to "break through" chronic pain that is being controlled by a scheduled opioid regimen. The development of fluctuations in pain intensity is challenging due to their unpredictable nature, rapid onset, and need for rapid treatment intervention. Breakthrough pain has been treated by using an extra opioid dose in addition to the scheduled opioid being used for pain. Recommendations for dose and frequency are based on expert opinion only, and have included dosing based on a percentage of the total opioid dose. Other recommendations include increasing the regularly scheduled opioid dose. Clinical trials have now focused on delivery of opioids that have both potency and a rapid onset of action. Lipophilic opioids have received a substantial amount of study due to their quick absorption and rapid onset of analgesia. Lipophilic opioids that have been studied to date include transmucosal fentanyl, sublingual fentanyl, intranasal sufentanil, and oral and sublingual methadone. Initial clinical trials have established the superiority of transmucosal fentanyl as a breakthrough analgesic when compared with immediate-release oral opioid formulations. Problems with bioavailability have led to a search for newer formulations of transmucosal delivery. Newer formulations, such as fentanyl transmucosal tablets, have been developed to ensure superior delivery for the patient suffering from breakthrough pain. The purpose of this paper is to discuss the current status of transmucosal tablet formulations for cancer breakthrough pain.