Efficacy of Bilastine, Dextromethorphan, and Phenylephrine Syrup in Patients With Dry Cough: A Phase 3 Randomised Trial.

Background Cough in common cold is often associated with rhinorrhoea and nasal congestion, requiring treatment with a cough suppressant, decongestant, and antihistamine. Bilastine is a non-sedating antihistamine, a preferred option over sedating antihistamines. A combination of bilastine, dextromethorphan, and phenylephrine is expected to provide non-sedating treatment for cough associated with a common cold or allergy. Methods In this open-label, randomized, active-controlled, multicentre, clinical trial, adult and adolescent subjects with acute dry cough received bilastine 6.6 mg/dextromethorphan 20 mg/phenylephrine 10 mg syrup (BDP) thrice daily or Alex syrup (chlorpheniramine maleate 4 mg/dextromethorphan 20 mg/phenylephrine 10 mg) for seven days. The objective of the study was to evaluate the efficacy and safety of a fixed-dose combination syrup of bilastine, dextromethorphan, and phenylephrine in cough relief in patients with cough associated with a common cold or allergy. Results Of 134 randomized subjects, 67 received BDP and the remaining 67 received Alex® syrup. The least-square mean (LSM) standard error (SE) change in cough severity from baseline on day 4 was 37.86 mm (2.012) in the BDP group (p < 0.001), with a mean difference between the two groups of -4.09 mm (95% CI: -9.68, 1.51). The confidence interval was within the non-inferiority (NI) limits of 30 mm, proving non-inferiority to Alex syrup (p-value for NI < 0.001). The drowsiness score was significantly lower in the BDP group on day 2 (difference -0.46, p = 0.004), day 4 (difference -0.99, p < 0.001), and day 8 (difference -0.97, p < 0.001). No serious or severe adverse event was reported, and adverse events were comparable between the two groups. Conclusion Bilastine/dextromethorphan/phenylephrine combination syrup is efficacious, safe, non-sedating, and non-inferior to Alex syrup in the treatment of acute dry cough due to a common cold or allergy.