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

BACKGROUND: Lozenges 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 1 mg lidocaine and 2 mg CPC. Single-agent lozenges containing 8 mg lidocaine have also been demonstrated to be significantly superior to placebo in confirmatory pain intensity assessments. This study compared a new lozenge formulation, containing 8 mg lidocaine and 2 mg CPC, with the currently marketed lozenge for the treatment and relief of sore throat symptoms in subjects diagnosed with a sore throat due to an upper respiratory tract infection (URTI). METHODS: In 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 8 mg lidocaine + 2 mg CPC (n = 125) or 1 mg lidocaine + 2 mg 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 100 mm visual analog scale. STPI was measured at baseline and regular intervals up to 240 min 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. RESULTS: No 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 4 h post-dose were higher with 1 mg lidocaine + 2 mg CPC than with 8 mg lidocaine + 2 mg 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. CONCLUSIONS: The modest difference in the pattern of effectiveness between the two treatments observed in this study does not support use of the 8 mg lidocaine + 2 mg CPC lozenge. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01265446. Registered on 20 December 2010.