Health Canada says it will review a declaration by American government experts who say a key ingredient in over-the-counter cold and allergy medications also available in this country does not work to get rid of nasal and sinus congestion.
Advisers to the U.S. Food and Drug Administration voted unanimously this week against the effectiveness of orally administered decongestantphenylephrine, found in medicationssuch as Sudafed and DayQuil.
The FDA must still decide whether to revoke the over-the-counter designation for medications containing phenylephrine, meaning they may need to be removed from store shelves.
Phenylephrine became a common ingredient in cold and allergy medicines after a 2006 U.S. law banned over-the-counter sales of products that contain another type of decongestant called pseudoephedrine, which, in large quantities, can be used to make methamphetamine.
That version is kept behind pharmacy counters.
Health Canada said Friday that, following a review, it will take any necessary action to ensure Canadians have access to safe and effective products.
Various studies have already questioned the benefits of phenylephrine, which is also available in nasal sprays, though the FDA said its advisory committee's latest vote only relates to phenylephrine in oral form, not the nasal spray.
Mina Tadrous, an assistant professor of pharmacy at the University of Toronto, said the advisers believe the oral phenylephrine products may be ineffective because they are metabolized too quickly in the liver.
"The nasal spray works. You're sending it to the place where you need help. If you take a pill it gets absorbed and then it passes by the liver and then it goes up to your nose."
In Canada, pseudoephedrine is still available in combination with other ingredients in some over-the-counter Tylenol and Advil products. Tadrous said it's best to consult a pharmacist about specific symptoms.
He said phenylephrine is an example of a medication that was approved in the late 1960s with "slight evidence" that it may work as a decongestant.
The most important factor for regulators was its safety.
The FDA said in a statement this week that its advisory committee did not raise any concerns about safety issues with the use of oral phenylephrine at the recommended dose.
The effectiveness of thousands of drugs has been re-evaluated over the years as part of lengthy processes involving few resources, but a challenge is deciding which older ingredients should undergo the same scrutiny if no safety issues have been flagged, Tadrous said.
— With files from The Associated Press
This report by The Canadian Press was first published Sept. 15.
Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.
Camille Bains, The Canadian Press
