The only effective OTC treatments for acute cough due to the common cold are older antihistamine/ decongestant products such as Wyeth's Dimetapp, according to revised guidelines issued by the American College of Chest Physicians.

"In patients with acute cough due to the common cold, over-the-counter combination cold medications, with the exception of an older antihistamine-decongestant, are not recommended until randomized, controlled trials prove they are effective cough suppressants," an executive summary of the guidelines states.

The summary, a final draft of which was posted on the ACCP website Jan. 11, updates the college's original evidence-based consensus panel report issued in 1998.

"Diagnosis & Management of Cough: Evidence-Based Clinical Practice Guidelines," authored by Richard Irwin, MD, University of Massachusetts Medical School, Worcester, Mass., et al., is slated to be published the week of Jan. 16, according to an ACCP spokesperson.

The document will appear as a supplement to the January issue of the ACCP's peer-reviewed journal, CHEST.

Most OTC cough expectorants and/or suppressants, including cough syrup and drops, do not treat the underlying cause of the symptom, according to an ACCP statement released Jan. 9.

"There is no clinical evidence that over-the-counter cough expectorants or suppressants actually relieve cough," Irwin said.

Therefore, the guidelines recommend that adults with acute cough or upper airway cough syndrome (previously named postnasal drip syndrome) use an older variety antihistamine such as diphenhydramine (Pfizer's Benadryl ) with or without a decongestant.

Acute cough patients "can be treated with a first-generation A/D preparation (brompheniramine and sustained release pseudoephedrine)" such as Dimetapp, the guidelines allow.

"There is considerable evidence that older type antihistamines reduce cough," Irwin maintained, "So, unless there are contraindications to using these medicines, why not take something that has been proven to work?"

Naproxen can also be used to decrease cough, according to the summary.

Endorsed by the American Thoracic Society and the Canadian Thoracic Society, "Diagnosis & Management of Cough" includes over 200 recommendations for diagnosing and treating acute (lasting less than 3 weeks), subacute (3-8 weeks) and chronic (over 8 weeks) cough.

Another recommendation of the guidelines with potential broad impact suggests that children age 14 and younger should not take OTC cough medicine "as patients, especially young children, may experience significant morbidity and mortality."

"Cough is very common in children. However, cough and cold medicines are not useful in children and can actually be harmful," Irwin stated.

The report includes recommendations for cough attributed to gastroesophageal reflux disease (GERD), upper respiratory infection (URI), asthma, tuberculosis, bronchitis, environmental causes and/or the common cold, among other factors.

When compared to the 1998 cough consensus statement, the accepted revisions "more narrowly focus the guidelines on the diagnosis and treatment of cough, the symptom, in adult and pediatric populations, and minimize the discussion of cough as a defense mechanism," according to the association.

They also "improve on the rigor of the evidence-based review," describe the methodology used, update and expand certain sections, and include new topics.

"If you look at the world literature as it is now, and well-performed scientific studies, and which medicines effectively suppress coughs related to common cold, all we could find was support for the older A/D combinations; nothing else," Peter Dicpinigaitis, MD, Director of the Montefiore Cough Center, Montefiore Medical Center, New York City, said in a phone interview Jan. 13.

"It doesn't logically follow that the opposite is true, that no patients can get any relief, but if you follow criteria of evidence from well-performed studies, it just hasn't been shown to be effective," Dicpinigaitis, ACCP panel member and one of the authors of the review, maintained. "That's the fact."

In addition, the ACCP does not recommend second-generation antihistamine products such as Schering-Plough's Claritin (loratadine) for treatment of cough due to cold, stating: "In patients with the common cold, newer generation non-sedating antihistaminesare ineffective for reducing cough and should not be used."

Claritin is not indicated for relief of cough.

Codeine and dextromethorphan, which can be found in some OTC cough/cold products, are usually formulated in doses too small to be effective, ACCP notes.

The different treatment strategies are graded on a letter scale as designated by the college's Health & Science Policy Grading System. "A" represents strong supporting data, "B," moderate, "C," weak, "D," negative, or "I," inconclusive data, no recommendation can be made.

The ACCP considered "quality of evidence" and "net benefit of the diagnostic and therapeutic procedure" while reviewing the available evidence, the summary notes.

Another guideline states that patients suffering acute cough due to cold should not take preparations containing zinc, such as Quigley's Cold-Eeze , which includes zinc gluconate glycine as an ingredient.

Cold-Eeze purports to "reduce the duration of the common cold up to 42%," according to the manufacturer's website. Patients are instructed to take Cold-Eeze "at the first sign of cold," which includes "cough" among its list of symptoms.

The ACCP's recommendations also address the treatment and handling of patients with cough due to gastroesophageal reflex disease (GERD).

"In some patients, cough due to GERD will favorably respond to acid suppression therapy alone."

In addition, "proton pump inhibitors may be effective when H2-antagonism has been ineffective," while patients experiencing ineffective proton pump inhibition treatment may experience improved efficacy by adding "prokinetic therapy and diet" to their PPI treatment.

Chronic cough is a predominant focus in the guidelines, which recommend that patients suffering a cough lasting over 8 weeks consult their physician.

"In patients suffering chronic or acute bronchitis, peripheral cough suppressants such as levodropropizine and moguisteine are recommended for the short-term symptomatic relief of coughing."

"In patients with cough due to URI, peripheral cough suppressants have limited efficacy and are not recommended for this use."

In response to the guidelines, the Consumer Healthcare Products Association stressed studies and regulatory history supporting OTC cough remedies for symptom relief in an acute setting.

"We agree with the ACCP recommendation that any chronic cough condition should be addressed by a healthcare professional," CHPA said in a Jan. 11 release.

"But, we stand by the judgments reached by leading regulatory agencies that OTC cough/cold medicines are safe and effective for the symptoms stated on their labels and when used as directed."

CHPA cites FDA's approval of OTC cough medicines for treatment of cough attributed to the common cold, as well as a 2004 CHPA-funded Northwestern University study demonstrating potential cost savings associated with using OTCs to treat certain URIs.

The ACCP concludes that "currently available cough suppressant therapy is severely limited by a dearth of effective agents and their unacceptable side effects."

In addition, "several classes of pharmacologic agents are currently under investigation in an attempt to develop clinically useful cough suppression" to be used in treatment.

As a result, the college makes a "strong recommendation based on expert opinion only" that further research should be conducted to elucidate the mechanisms, production, conditions, assessment and treatment of cough.

- Melina Vissat

Most OTC Cough Meds Dismissed By Chest Physicians Guidelines

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