Fentanyl, also spelled fentanil, is an opioid which is used as a pain medication and together with other medications for anesthesia. It has a rapid onset and effects generally last less than an hour or two. Fentanyl is available in a number of forms including by injection, as a skin patch, and to be absorbed through the tissues inside the mouth.
Common side effects include nausea, constipation, sleepiness, and confusion. Serious side effects may include a decreased effort to breathe (respiratory depression), serotonin syndrome, low blood pressure, or addiction. Fentanyl works in part by activating μ-opioid receptors. It is about 75 times stronger than morphine for a given amount. Some fentanyl analogues may be as much as 10,000 times stronger than morphine.
Fentanyl lozenges (Actiq) are a solid formulation of fentanyl citrate on a stick in the form of a lollipop that dissolves slowly in the mouth for transmucosal absorption. These lozenges are intended for opioid-tolerant individuals and are effective in treating breakthrough cancer pain. It has also been used for breakthrough pain for patients with nonmalignant (not cancer related) pain, but this application is controversial. The unit is a berry-flavoured lozenge on a stick swabbed on the mucosal surfaces inside the mouth—inside of the cheeks, under and on the tongue and gums—to release the fentanyl quickly into the system. It is most effective when the lozenge is consumed within 15 minutes. About 25% of the medication is absorbed through the oral mucosa, resulting in a fast onset of action, and the rest is swallowed and absorbed in the small intestine, acting more slowly. The lozenge is less effective and acts more slowly if swallowed as a whole, as despite good absorbance from the small intestine there is extensive first-pass metabolism, leading to an oral bioavailability of about 33% as opposed to 50% when used correctly, (25% via the mouth mucosa and 25% via the gut).
Actiq is produced by the pharmaceutical company Cephalon on a plastic stick; this provides the means by which the medication can maintain its placement while it dissolves slowly in the mouth for absorption across the buccal mucosa, in a manner similar to sublingual buprenorphine/naloxone film strips. An Actiq lozenge contains 2 grams of sugar (8 calories). Actiq has been linked to dental decay, with some users who had no prior dental issues suffering tooth loss, and in the U.S many users have started their own Facebook pages to educate users about the severe dental issues caused by the so-called fentanyl lollipops. CBS News reported the issue 28 September 2009. The status of a sugar-free version, called Actiq-SF, is unclear. Since the release of Fentora—an effervescent buccal fentanyl tablet for breakthrough cancer pain—Cephalon has indefinitely postponed plans to release a sugar-free version of Actiq.