Efficacy of 8mg lidocaine and 2mg cetylpyridinium chloride (CPC) fixed-combination lozenges on sore throat pain intensity compared with 1mg lidocaine and 2mg CPC fixed-combination lozenges in subjects with sore throat due to upper respiratory tract infection: a randomized double-blind parallel-group single-dose study

BackgroundLozenges containing lidocaine and cetylpyridinium chloride (CPC) are commonly used for the treatment of sore throat. The lidocaine acts locally to provide pain relief and the CPC has an antiseptic effect. Mebucaine CL, a well-established fixed-combination sore throat lozenge, contains 1mg lidocaine and 2mg CPC. Single-agent lozenges containing 8mg lidocaine have alsobeen demonstrated to be significantly superior to placebo in confirmatory pain intensity assessments. This study compared a new lozenge formulation, containing 8mg lidocaine and 2mg CPC, with the currently marketed lozenge for the treatment and relief of sore throatsymptoms in subjects diagnosed with a sore throat due to an upper respiratory tract infection (URTI).MethodsIn this double-blind parallel-group study, 250 adults with a sore throat due to an URTI were randomized to receive a single lozenge containing either 8mg lidocaine +2mg CPC (n=125) or 1mg lidocaine +2mg CPC (n=125). The primary efficacy endpoint of the study was the change in sore throat pain intensity (STPI) between baseline (immediately pre-treatment) and the 2-h post-dose assessment, measured on a 100mm visual analog scale. STPI was measured at baseline and regular intervals up to 240min after the lozenge was administered (evaluated in clinic). Any difficulty in swallowing and time to onset and duration of the analgesic effect were also assessed.ResultsNo increase in efficacy was demonstrated with the higher dose of lidocaine. The difference in the 2-h post-dose change in STPI was not statistically significant between the treatments. There was only one statistically significant difference between the treatments in all of the efficacy outcomes assessed: pain relief scores at 4h post-dose were higher with 1mg lidocaine +2mg CPC than with 8mg lidocaine +2mg CPC (P=0.0461). The most commonly reported adverse event (AE) was a headache; the only other AE experienced by more than one subject was throat irritation. No severe adverse events were reported during the assessment period.ConclusionsThe modest difference in the pattern of effectiveness between the two treatments observed in this study does not support use of the 8mg lidocaine +2mg CPC lozenge.Trial registrationClinicalTrials.gov, NCT01265446. Registered on 20 December 2010.