Efficacy of high‑dose ambroxol for paraquat poisoning: A meta‑analysis of randomized controlled trials

Background: Paraquat (PQ) poisoning is characterized by rapidly progressive acute poisoning with high mortality and no specific antidote. Although some clinical studies have been conducted to investigate the benefits of high‑dose ambroxol as an adjuvant treatment for PQ poisoning, the efficacy is controversial. Materials and Methods: After searching for relevant articles in English and Chinese databases from 1978 to 2019 according to the keywords (paraquat poisoning/methy viologen/gramoxone, and ambroxol/mucosolvan/Bromhexine), we found seven articles that met our inclusion and exclusion criteria. A meta‑analysis was performed using fixed‑effects model and random‑effects model according to the I2 value in Stata software (version 15.0). Four outcome indicators (hospital mortality, partial pressure of oxygen (PaO2), oxygenation index (PaO2/FiO2), and survival time of the deceased patients) were of interest to us. Results: The meta‑analysis showed that adjuvant treatment with high doses of ambroxol increased PaO2 (weighted mean difference [WMD] = 13.73 [mmHg], 95% confidence interval [CI]: 8.68–18.79, Z = 11.80, P < 0.001), PaO2/FiO2 (WMD = 38.81 [mmHg], 95% CI: 29.85–47.76, Z = 8.49, P = 0.000), and survival time of the deceased patients (WMD = 2.58 [d], 95% CI: 0.97–4.18, Z = 3.15, P = 0.002) compared with usual treatment. Treatment with high doses of ambroxol also appeared to reduce the hospital mortality (relative risk = 0.69, 95% CI: 0.55–0.86, Z = 3.25, P = 0.001). Conclusion: This study found that high‑dose ambroxol is an effective therapy for PQ poisoning and may reduce the in‑hospital mortality.