I was at the chemist today, begging for more Codral. To my surprise (and Jenn’s), the (very sympathetic) pharmacist told us outright that the phenylephrine (PE) versions don’t do anything, that there was no good research showing effectiveness, that the Pharmacist’s Guild recommended against it, and that we should insist on the real thing with pseudoephedrine (PSE).
To say I was shocked doesn’t cover it.
So, I went looking this afternoon; turns out, she was right about the research (not that I’m surprised).
The University of Florida published research in 2006 arguing that PE “is ineffective at the Food and Drug Administration’s approved dose”.
Hendeles and Hatton (2006) is a good resource. Turns out that PE is pretty thoroughly metabolised by the gut and liver, meaning that “only 38% of the dose reaches the systemic circulation, compared with 90% of a pseudoephedrine dose.” A “randomized, double blind, placebo-controlled, crossover study” found PE was “no more effective than a placebo”.
Hatton et al (2007)concluded: “There is insufficient evidence that oral phenylephrine is effective for nonprescription use as a decongestant. The FDA should reclassify oral phenylephrine from Category I (safe and effective) to Category III, which requires additional studies to show safety and efficacy.” based on an analysis of 16 studies.
The only significantly positive meta-analysis I could find (but I’m certainly not an expert) was Kollar, Schneider, Waksman and Krusinska (2007), and (not to be too cynical) they work for GSK, the Consumer Healthcare Products Association and Wyeth.
Eccles (2006) argues that substituting PSE with PE is an “illogical way to control methamphetamine abuse”. Having actually read some research on the subject, I tend to agree.