The US Food and Drug Administration has approved Subsys (fentanyl) sublingual spray. Subsys is a sublingually-administered formulation of fentanyl which provides relief to patients who experience episodes of breakthrough cancer pain. Breakthrough cancer pain is characterized by sudden, often unpredictable, episodes of intense pain which can peak in severity at three to five minutes despite background pain medication. Subsys is approved in cancer patients 18 years of age and older who are already receiving and who are tolerant to opioid therapy for their underlying persistent cancer pain.