Dextromethorphan is one of the most widely used
antitussives for the treatment of
cough associated with acute
upper respiratory tract infection. However, there is very little data to support the efficacy of
dextromethorphan in this disease state. This aim of this study was to obtain more information about the efficacy of a single dose of 30 mg
dextromethorphan in the treatment of
cough associated with acute
upper respiratory tract infection. The study was a double-blind, stratified, randomized and parallel group design. Both objective and subjective measurements of
cough were recorded over 10-min recording periods in a quiet room before (baseline) and at 90, 135 and 180 min
after treatment. Forty-three patients (30 females and 13 males), mean age 22.9 years (range 18-46 years), with acute dry or slightly productive
cough and otherwise healthy were included in the study. Patients were randomized to placebo treatment (n = 22) and
dextromethorphan treatment (n=21). The results showed similar trends in both treatment groups with statistically significant reductions (P < 0.05) in
cough sound pressure level (CSPL),
cough frequency (CF) and subjective scores for
cough severity within treatment groups but little difference between the treatment groups during the study period. The only statistically significant difference between treatment groups was for the mean CSPL changes from baseline to 90 min (P=0.019). There was a significant positive correlation between CSPL and CF (r = 0.752, P= 0.000) for changes in
cough measurements from baseline to 90 min
after treatment and this indicates that CSPL may be a useful measure of
cough severity. This study provides very little if any support for clinically significant
antitussive activity of a single 30 mg dose of
dextromethorphan in patients with
cough associated with acute
upper respiratory tract infection.