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Re: Dextromethorphan for acute cough: additonal data not reported in the subject review

Dear Editor

As an academic pediatrician interested in the treatment of cough, I read the recent review by Schroeder and Fahey [1] with great interest. However, I feel that this review, like others published recently, [2,3] are incomplete with regards to the data describing the use of dextromethorphan for acute cough due to upper respiratory tract infection (URTI). In addition to the study that was cited by Taylor et al,[4] there are three additional subjective placebo controlled trials evaluating the efficacy of dextromethorphan that were not described in the review and one recent manuscript describing objective data in adults.

The first paper from 1961 by Gruber and Carter [5] was a placebo controlled trial using inmates of a home for children with cough due to URTI. Dextromethorphan, propoxyphene derivatives, or placebo were given to these children who over several days subjectively rated the antitussive and antiexpectorant effect of the medications. The authors found a significant improvement in cough for those children given dextromethorphan compared with placebo. They also reported a dose response effect with greater improvement seen with a 30 mg dose compared with 15 mg. The age, weight, sex and other descriptive or demographic variables were unfortunately not reported in this investigation.

Two years later a similar study by Carter [6] found similar results. The medications and placebo were combined with acetylsalicyclic acid (ASA) in this investigation. The age range of the children was 1 to 15 years with a mean of 4.1 years. Dextromethorphan plus ASA was superior to ASA for numerous variables including cough frequency, cough severity, frequency of expectoration, amount expectorated, and duration of cough. The children given dextromethorphan also reported that they were less bothered by their cough.

More recently, a Scandanavian group led by Korppi [7] compared dextromethorphan with and without salbutamol to placebo for cough due to URTI. These results differed from the two described above by showing a large placebo effect. Alone or in combination with the beta agonist, dextromethorphan was not superior to placebo for cough symptoms or general condition.

Finally, there is no objective pediatric data in existence comparing dextromethorphan alone to placebo for the treatment of cough due to URTI. Alternatively, the recent paper by Pavesi et al.[8] describes six adult double-blind, parallel-group, single-dose, placebo controlled trials comparing dextromethorphan to placebo in 710 patients. The trials demonstrated that dextromethorphan reduced cough bouts, components, effort, and intensity with an increase in cough latency. This group described their computerized cough acquisition and analysis system in detail while providing their results.

In summary, it appears that these data combined with those described in the review by Schroeder and Fahey still leave doubt regarding the efficacy of over-the-counter cough medications for the treatment of cough due to URTI. While the older data may contain methodologic flaws, the results are still relevant to reviews on the topic and should have been included. As a practicing pediatrician in the United States, I will continue to follow the guidelines put forth by the American Academy of Pediatrics [9] that concluded that there is no current indication for dextromethorphan as an antitussive. However, these data clearly show a need for further investigations using dextromethorphan to settle this debate over its efficacy once and for all.

Ian M. Paul, M.D.
Penn State College of Medicine
Department of Pediatrics
Division of General Pediatrics
Hershey, PA
USA

References

(1) Schroeder K, Fahey T. Should we advise parents to administer over the counter cough medicines for acute cough? Systematic review of randomised controlled trials. Arch Dis Child 2002;86:170-5.

(2) Schroeder K, Fahey T. Systematic review of randomised controlled trials of over the counter cough medicines for acute cough in adults. BMJ 2002;324:1-6.

(3) Schroeder K, Fahey T. Over-the-counter medications for acute cough in children and adults in ambulatory settings. Cochrane Database Syst Rev 2001;(3):CD001831.

(4) Taylor JA, Novack AH, Almquist JR, Rogers JE. Efficacy of cough suppressants in children. J Pediatr 1993;122:799-802.

(5) Gruber CM, Carter CH. A measure of the effectiveness of propoxyphene antitussives in children. Am J Med Sci 1961;242:443-6.

(6) Carter CH. A clinical evaluation of the effectiveness of novrad and acetylsalicylic acid in children with cough. Am J Med Sci 1963;245:713-7.

(7) Korppi M, Pietikainen M, Laurikainen K, Silvasti M. Antitussives in the treatment of acute transient cough in children. Acta Paediatr Scand 1991;80:969-71.

(8) Pavesi L, Subburaj S, Porter-Shaw K. Application and validation of a computerized cough acquisition system for objective monitoring of acute cough: A meta-analysis. Chest 2001; 120: 1121-8.

(9) American Academy of Pediatrics, Committee on Drugs. Use of codeine- and dextromethorphan-containing cough remedies in children. Pediatrics 1997;99:918-20.