A study has assessed the effectiveness of Phenylephrine, the active ingredient in products such as Actifed, Sudafed PE, and Tylenol Sinus.

The meta-analysis of 15 previous studies concludes that the standard 10 mg dose of the drug appears to be no more effective than placebo and suggests that the FDA should require additional studies to prove the drug's safety and efficacy.

The reviewed studies contained objective assessments of Phenylephrine's efficacy, primarily nasal airway resistance, as well as subjective measurements of patient-reported congestion relief.
Changes in both measures varied widely among the studies and when statistically combined using meta-analysis techniques, no consistent benefit from the drug could be detected. Reasons for the inconsistencies have not been determined.

Phenylephrine is a drug known to have a low oral bioavailability. As a result, higher-than-expected doses may be necessary to achieve measurable effects. However, it remains to be seen whether these higher doses could increase the risk of adverse effects such as increases in blood pressure or heart rate in some patients.

Phenylephrine, Pseudoephedrine, and Phenylpropanolamine were declared safe and effective for nonprescription use by the US Food and Drug Administration in 1976. Since then, Phenylpropanolamine was removed from the market after being associated with hemorrhagic strokes, and legislation now requires Pseudoephedrine products to be kept " behind the counter " and sold in small quantities to prevent their use in the illegal manufacture of Methamphetamine. This leaves Phenylephrine as the primary ingredient in OTC decongestants available today.

Source: Annals of Pharmacotherapy, 2007

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