Efficacy of Ambroxol lozenges for pharyngitis: a meta-analysis

Ambroxol has a local anaesthetic action and is marketed for pain relief for sore throat. The objective is to examine the efficacy and safety of ambroxol for the relief of pain associated with acute uncomplicated sore throat.

A systematic review of the literature and meta-analysis. Selection criteria consisted of randomized controlled trials which compared ambroxol to placebo or any other treatment for sore throat. Two reviewers independently assessed for relevance, inclusion, and risk of bias. Weighted mean differences (WMDs) were calculated and are reported with corresponding 95% confidence intervals (CIs).

From 14 potentially relevant citations, five trials reported in three publications met the inclusion criteria, three of them were published twice. Ambroxol lozenges were compared in different dosages (5-30 mg) with mint flavoured lozenges and once with benzocaine. Main outcome was a ratio of pain reduction measured repeatedly over 3 h compared to baseline on 6-item verbal rating scale. A total of 1.772 adult patients participated in the trials. Pain intensity decreased in both study arms. A meta-analysis of the 5 controlled trials resulted in a difference in pain reduction compared to placebo of -0.11 (95% CI [-0.15, -0.07]; p < 0.0001) favouring ambroxol 20 mg. Quality of reporting of the studies was low. Ambroxol is slightly more effective in relieving pain in acute sore throat than mint flavoured lozenges over a period of 3 h. However, the additional benefits of ambroxol beyond three hours, remain unclear given that more than 50% of patients using mint flavoured lozenges for pain relief reported good or very good efficacy after 1 day compared to 69% with ambroxol. Ambroxol is a safe option for individual patients with mainly local symptoms asking for treatment.