An asthma medicine widely used around the world to stop children's coughs has no provable benefit for that purpose and may cause harm, a new review of existing studies reports.
The class of drugs known as methylxanthines is no longer used to treat childhood asthma in Western countries, having been replaced by corticosteroids. But the drugs remain the leading therapy for asthma in the developing world, where they are also used to cure routine coughing in children.
"We found a lack of good evidence for using methylxanthines for children's cough that was not associated with other asthma symptoms," says lead study author Anne Chang, M.D., at Royal Children's Hospital in Queensland, Australia.
These medications are known by brand names Accubron Syrup, Aquaphyllin Syrup, Asmalix Elixir, Lanophyllin Elixir, Slo-Phyllin Syrup, Theoclear-80 Syrup, and Theolair Solution.
"This drug was widely abandoned in the U.S. when safer alternatives became available for the immediate relief of wheezing," says Richard L. Gorman, M.D., chair of the American Academy of Pediatrics Committee on Drugs.
The review appears in the July issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Methylxanthines work in part by relaxing the bronchial airways, which helps to reduce coughing, wheezing, shortness of breath or difficulty breathing. They are also potentially dangerous for children, impairing the developing nervous system, and causing irritability, seizures and cardiac arrhythmias that lead to death.
Chang and colleagues searched the published literature for studies that analyzed methylxanthines' effectiveness for children suffering from coughing not related to disorders like cystic fibrosis or asthma. They found four studies, but they were of a limited design, not solid enough to suggest methylxanthine should be used for garden-variety kids' coughs, according to the study.
"The Cochrane Review states there is no data to support the use of methylxanthines. I would strongly concur," Gorman says.
Given the challenges chronic coughing poses for children, Chang and colleagues say methylxanthines should be considered as a potential treatment, but only after more research and only with careful awareness of its side effects.
"Knowledge is always desirable," Gorman notes. "While methylxanthines would not be my first choice of agents to study, a well designed trial or series of trials that demonstrated efficacy in certain situations or lack of efficacy in the face of well known toxicities would be very welcome."
"Information that could be used to stop unsafe practices is as important as information that can be used for effective new therapies," Gorman says.