Efficacy of AMC/DCBA lozenges for sore throat: A systematic review and meta-analysis.

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Lozenges containing Amylmetacresol and 2,4-Dichlorobenzylalcohol (AMC/DCBA, eg Strepsils® ) are marketed as a remedy for acute sore throat. This over-the-counter formulation has antiseptic and local anaesthetic qualities. The objective of this systematic review and meta-analysis is to evaluate the efficacy and safety of AMC/DCBA for the relief of pain associated with acute uncomplicated sore throat. A systematic review of Literature was conducted using databases Medline, Embase and Cochrane to identify randomised controlled trials comparing AMC/DCBA against placebo or alternative local treatment options for acute uncomplicated sore throat. An additional hand search was performed. Two reviewers independently assessed citations for relevance, inclusion criteria and risk of bias. Meta-analysis was performed on included trials and standardised mean differences (SMD; dCohen ) with 95% confidence intervals (CIs) were calculated. The literature search yielded 77 citations, 3 of which met the inclusion criteria. AMC/DCBA lozenges (0.6mg Amylmetacresol, 1.2mg 2, 4-Dichlorobenzylalcohol) were compared with unflavoured, non-medicated lozenges. The AMC/DCBA formulation additionally contained lidocaine in one and flavouring additives in another trial. A total of 660 adults participated in the included trials. Primary outcome was reduction in pain intensity against baseline, 2hours after intervention compared with placebo group. Fixed effects meta-analysis resulted in a standardised mean difference in pain intensity of -0.6 (-0.75; -0.45) on an 11-point ordinal rating scale, favouring the AMC/DCBA lozenges. Secondary outcomes were sore throat relief, difficulty swallowing and throat numbness. No serious side effects were reported, whereas mild side effects like headache, cough, nasal congestion and irritation of the oral cavity, were reported in up to 16% of subjects in both groups. All included trials were sponsored by a manufacturer of AMC/DCBA containing lozenges. Lozenges with AMC/DCBA can be a safe treatment option to relieve pain in patients with uncomplicated sore throat looking for local treatment options and valuing the modest additional effect compared with non-medicated lozenges. Registration: PROSPERO CRD42015008826.