Onset of analgesia by a topically administered flurbiprofen lozenge: a randomised controlled trial using the double stopwatch method

The double stopwatch (DSW) method for determining the onset of analgesic activity has been implemented extensively by investigators studying orally administered drugs. The aim of this randomised, placebo-controlled trial was to use the DSW method to determine the time to onset of analgesia of a single dose of a topically administered non-steroidal anti-inflammatory drug, flurbiprofen 8.75？mg lozenge. Adults with acute sore throat (n？=？122) were examined to confirm the presence of tonsillopharyngitis (Tonsillo-Pharyngitis Assessment) and sore throat pain of at least moderate intensity (≥6 on a 0–10 Sore Throat Scale). Lozenges containing flurbiprofen 8.75？mg or inert ingredients (identically flavoured) were administered under double-blind conditions in the clinic while patients assessed pain and pain relief over 3？hours. Onset of analgesia was determined using the DSW method and reported as the Kaplan–Meier median time to meaningful relief. The median time to first perceived relief was also documented. About 78% of flurbiprofen-treated patients reported meaningful pain relief compared with 48% of placebo-treated patients (p？<？0.01); median time to meaningful relief for flurbiprofen-treated patients was 43？minutes (placebo-treated patients were right-censored due to non-responsivity; p？=？0.01). Median time to first perceived pain relief was 11？minutes for flurbiprofen-treated patients and 19？minutes for placebo-treated patients (p？=？0.03). Flurbiprofen lozenge was well tolerated, with no serious adverse events occurring and no patient discontinuing due to an adverse event. These results indicate that the DSW method can be successfully applied to the evaluation of the onset of action of a locally administered analgesic in patients with acute sore throat, demonstrating that the onset of action (time to meaningful pain relief) of flurbiprofen lozenge was <45？minutes