Popular decongestant ingredient ineffective, US FDA reveals

A key ingredient in well-known decongestant products like Sudafed PE and Benadryl Allergy Plus Congestion, phenylephrine, has been deemed ineffective when taken orally, according to a US Food and Drug Administration (FDA) panel. The FDA's Nonprescription Drug Advisory Committee (NDAC) reached this conclusion during a meeting held on September 12.

After a comprehensive review of years' worth of data, the NDAC unanimously found that phenylephrine, a common decongestant ingredient, can provide relief for nasal congestion when administered directly into the nose, such as through a nasal spray. However, the panel determined that it does not effectively alleviate congestion when ingested orally. Less than 1% of the drug reaches the bloodstream and the nasal tissues it is intended to target when taken orally.

Phenylephrine functions by constricting blood vessels in the nose and sinuses, but this mechanism does not work efficiently when the drug is taken by mouth. The committee pointed out that none of the original studies on the drug met modern standards of study design or conduct. Earlier research yielded inconsistent results and relied on outdated statistical methods and technology that would not meet current regulatory standards.

Phenylephrine was initially approved as an over-the-counter oral and intranasal decongestant back in 1976. However, its use became more widespread in 2005 as a substitute for pseudoephedrine, another decongestant that had been restricted due to its potential use in making methamphetamine. This led to phenylephrine being included in many over-the-counter decongestant products, making it the most popular decongestant in the United States despite ongoing debates about its effectiveness.

In 2007, researchers from the University of Florida petitioned the FDA to review the effectiveness of phenylephrine in adults. Although they provided some evidence of its ineffectiveness in oral formulations, the FDA advisers requested additional data. Since then, three large clinical trials have been conducted, with results demonstrating that the drug is no more effective than a placebo. These trials also showed that very little phenylephrine enters the bloodstream when taken orally.

The NDAC has concluded that the newly acquired clinical data confirm that orally administered phenylephrine is not effective at any dose that can be developed while maintaining safety margins. The FDA will now need to decide whether to revoke phenylephrine's designation as "generally recognized as safe and effective." If this designation is revoked, products containing phenylephrine may need to be removed from shelves and reformulated by suppliers.

[Information sourced from Live Science]