Study objective: The purpose of the meta-analysis was to understand the antitussive effect of treatment with dextromethorphan hydrobromide, 30 mg, vs placebo over a 3-h treatment period in patients with cough due to uncomplicated upper respiratory tract infection (URTI), and to show that the computerized system for acquisition and analysis of cough sound was consistent and reproducible across the individual studies.
Study design: The six studies used for the meta-analysis were randomized, double-blind, parallel-group, single-dose, placebo-controlled studies with a 3-h postdose cough evaluation period.
Setting: One study was conducted in Durban, South Africa, and five studies were conducted in Bombay, India. Four studies took place in clinics, and two studies were in-home studies.
Patients: Seven hundred ten adult patients with cough due to uncomplicated URTI who were otherwise healthy and who satisfied the inclusion/exclusion criteria for the meta-analysis.
Measurements and results: For each patient, a standard baseline was calculated pretreatment, then a 3-h continuous cough recording was made after treatment was initiated. Five efficacy variables were measured in 30-min intervals: cough bouts, cough components, cough effort, cough intensity, and cough latency. The meta-analysis showed consistent results across most of the studies for each of the efficacy variables. It demonstrated significantly greater overall reductions in cough bouts, cough components, and cough effort, and an increase in cough latency for patients treated with dextromethorphan hydrobromide, 30 mg, vs those treated with placebo.
Conclusion: The results of a meta-analysis of the six clinical studies show that the antitussive effect of a single dose of dextromethorphan hydrobromide, 30 mg, has been established. The consistent nature of the results shows that the computerized cough acquisition and analysis system is a valid and reproducible methodology for evaluating cough associated with URTI.