Managing breakthrough pain.

Breakthrough cancer pain (BTcP) has been defined as a transitory increase in pain intensity on a baseline pain of moderate intensity in patients on regularly administered analgesic treatment. This review provides updated information about the classification, assessment, and treatment of BTcP, with special emphasis on the use of opioids. Due to its slow onset to effect, oral opioids cannot be considered an efficacious treatment of BTcP. More recently, different technologies have been developed to provide fast pain relief with potent opioid drugs, such as fentanyl, delivered by noninvasive routes. Transmucosal, buccal, sublingual, and intranasal fentanyl have been shown to provide rapid analgesia in comparison with oral morphine or placebo and are available for clinical use in most countries. All the studies performed with these delivery systems have recommended that these drugs should be administered to opioid-tolerant patients receiving doses of oral morphine equivalents of at least 60 mg. The need of titrating opioid doses for BTcP has been commonly recommended in all the controlled studies, but never has been substantiated in appropriate studies.