Efficacy and Safety of a Fixed Combination Phytomedicine in the Treatment of the Common Cold (Acute Viral Respiratory Tract Infection): Results of a Randomised, Double Blind, Placebo Controlled, Multicentre Study

Summary Objective The common cold (acute viral respiratory tract infection) is one of the most frequent diseases in man, world-wide. Clinically relevant efficacy should include early improvement of all symptoms. Results of a clinical trial of a commercially available fixed combination herbal remedy (Radix echinaceae, Radix baptisiae, Herba thujaej are reported here. The aim of this study was to verify clinical efficacy shown in recent studies under (i) good clinical practice (GCP) quality assurance and (ii) common situations at family doctors. Methods Patients attending one of 15 study centres (practitioners) as a result of an acute common cold were randomised to the double-blind placebo-controlled study. Three tablets of study medication were applied t.i.d. for 7 to 9 days. Patients daily documented the intensity of 18 cold symptoms, as well as the cold overall, using a 10-point scale and estimated their general well-being using the Welzel-Kohnen colour scales. Additionally, the severity of illness was assessed by the physician on days 4 and 8 (CGI-1). The main and confirmatory outcome measure was expressed as a total efficacy value. This was gauged from the z-standardised AUC values of the primary endpoints (rhinitis score, bronchitis score, CGI-1 and general well-being). Adverse events, overall tolerability, vital signs and laboratory parameters were documented. Results 263 patients were included. For safety analysis, all patients were used. 259 patients were evaluable for primary efficacy analysis (ITT). Results were confirmed analysing only the 238 valid cases (VCs). The primary efficacy parameters showed the superiority of the herbal remedy over placebo (p < 0.05). Effect size was 20.6% of the standard deviation (90% CI: 0.04-41.1%; ITT) and 23.1%, (1.7-44.5%; VC). In relation to the general well-being, the effect size was 33.9%o of the standard deviation (12.5-55.3%; VC). Patients who suffered from at least moderate symptom intensity at baseline showed response rates (at least 50% improvement of the global score, day 5) of 55.3% in the herbal remedy group and 27.3% in the placebo group (p - 0.017; NNT = 3.5). In the subgroup of patients who started therapy at an early phase of then-cold, the efficacy of the herbal remedy was most prominent (p = 0.014 for the primary efficacy parameter). The therapeutic benefit of the herbal remedy had already occurred on day 2 and reached significance (p < 0.05) on day 4, and continued until the end of the treatment