The physiochemical characteristics of the potent synthetic opioid agonist fentanyl make itideal for noninvasive transmucosal delivery. Studies of oral transmucosal fentanyl citrate(OTFC), a candied matrix formulation administered orally as a palatable lozenge on a stick,have investigated and determined this analgesic's pharmacokinetics and pharmacodynamicsin a number of clinical settings, including premedication before surgery, acute analgesia forpainful medical procedures, and, most recently, for the control of breakthrough cancer pain.The onset to meaningful pain relief in patients with acute pain from surgery or breakthroughpain from cancer is between 5 and 10 minutes after initiating OTFC use, equivalent to intravenousmorphine. Analgesic dose equivalency studies suggest that OTFC is, on average, about10 times more potent than morphine, although, in randomized, controlled, and blinded studies,many patients who were using relatively high doses of opioid anlagesics on an aroundthe-clock schedule for control of cancer pain reported that even a low dose of OTFC (i.e., 200g) provided adequate relief from breakthrough pain. Side effects from OTFC are similar incharacter and frequency to other opioids, including sedation, nausea, and pruritus. These effectsappear to wane rapidly with repeated use of this medication. To date there have beenno reported serious adverse events in any of the population groups studied or treated withOTFC.
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