Data show the effective dose of a rapid-onset, transmucosal opioid for breakthrough pain (BTP) is not related to the around-the-clock (ATC) dose of the drug. No data exist, however, on more traditional, short-acting oral opioids. In a head-to-head, 46-center study comparing fentanyl buccal tablet (FBT) with oxycodone immediate-release (OxyIR) for BTP, opioid-tolerant patients titrated FBT and OxyIR to a successful dose that provided adequate analgesia without unacceptable adverse events (AEs) during 2 randomized, open-label periods. The doses of FBT (200, 400, 600, 800 mcg) and OxyIR (15, 30, 45, 60 mg) were selected based on the relative potency estimate that FBT 100 mcg is equivalent to OxyIR 7.5 mg. Efficacy was evaluated during 2 subsequent randomized, crossover, double-blind, double-dummy periods. 320 patients received treatment; 203 found a successful dose of both drugs and 183 were evaluable for efficacy. During the titration periods, 60 patients discontinued while receiving FBT and 69 while receiving OxyIR. Reasons for discontinuation were similar between treatments. 162/320 (51%) patients reported AEs, which were similar between treatments. There was no linear relationship between the successful dose of FBT or OxyIR and the ATC opioid dose. The successful doses of FBT and OxyIR exhibited a strong concordance, as measured by Kendall's tau statistic (tau=0.62; P<0.0001). Of the patients who entered the study taking OxyIR and identified a successful dose of each drug, 78/96 (81%) titrated to a higher dose of OxyIR than was used at study entry. In conclusion, the titrated, successful dose of OxyIR for BTP was not predicted by the ATC opioid dose. However the successful OxyIR dose was concordant with a dose of FBT estimated to be equivalent. The tolerability profiles were similar. (Sponsored by Cephalon, Inc.) Data show the effective dose of a rapid-onset, transmucosal opioid for breakthrough pain (BTP) is not related to the around-the-clock (ATC) dose of the drug. No data exist, however, on more traditional, short-acting oral opioids. In a head-to-head, 46-center study comparing fentanyl buccal tablet (FBT) with oxycodone immediate-release (OxyIR) for BTP, opioid-tolerant patients titrated FBT and OxyIR to a successful dose that provided adequate analgesia without unacceptable adverse events (AEs) during 2 randomized, open-label periods. The doses of FBT (200, 400, 600, 800 mcg) and OxyIR (15, 30, 45, 60 mg) were selected based on the relative potency estimate that FBT 100 mcg is equivalent to OxyIR 7.5 mg. Efficacy was evaluated during 2 subsequent randomized, crossover, double-blind, double-dummy periods. 320 patients received treatment; 203 found a successful dose of both drugs and 183 were evaluable for efficacy. During the titration periods, 60 patients discontinued while receiving FBT and 69 while receiving OxyIR. Reasons for discontinuation were similar between treatments. 162/320 (51%) patients reported AEs, which were similar between treatments. There was no linear relationship between the successful dose of FBT or OxyIR and the ATC opioid dose. The successful doses of FBT and OxyIR exhibited a strong concordance, as measured by Kendall's tau statistic (tau=0.62; P<0.0001). Of the patients who entered the study taking OxyIR and identified a successful dose of each drug, 78/96 (81%) titrated to a higher dose of OxyIR than was used at study entry. In conclusion, the titrated, successful dose of OxyIR for BTP was not predicted by the ATC opioid dose. However the successful OxyIR dose was concordant with a dose of FBT estimated to be equivalent. The tolerability profiles were similar. (Sponsored by Cephalon, Inc.)