Meta-analysis of the efficacy of a single dose of phenylephrine 10 mg compared with placebo in adults with acute nasal congestion due to the common cold
Although nonprescription oral phenylephrine 10 mg has been judged "generally recognized as safe and effective" by the US Food and Drug Administration (FDA), its efficacy as a nasal decongestant has been questioned. This study assessed available data on the efficacy of oral phenylephrine 10 mg as a nasal decongestant. Three sources were used to identify potentially relevant publications--the bibliography of the phenylephrine section of the 1976 FDA monograph on over-the-counter cold, cough, allergy, bronchodilator, and antiasthmatic products; a 2004 Cochrane Review of nasal decongestants for the common cold; and a search of MEDLINE from 1966 through January 2007 using the term phenylephrine nasal. To be included in the analyses, studies had to have a single-dose, randomized, placebo-controlled design; involve an orally administered product in which phenylephrine 10 mg was the sole active ingredient; enroll patients with acute nasal congestion due to the common cold; evaluate nasal airway resistance (NAR) as the efficacy end point; and have sufficient data in the study report to allow reanalysis and/or meta-analysis of phenylephrine 10 mg versus placebo. Reanalysis of individual studies and fixed-effects and random-effects meta-analyses were performed. Statistical significance at 30 and 60 minutes after dosing (the primary time points) and a >or=20% reduction in NAR from baseline were considered indicative of a clinically meaningful difference. Fifteen potentially relevant studies were identified, of which 8 met the inclusion criteria. Data from 7 crossover studies involving a total of 113 subjects were reanalyzed and then pooled for meta-analysis; results from the initial phase of the eighth study, a parallel-group trial involving 50 subjects, were included in the reanalysis of individual studies but not in the meta-analyses. Significant differences in favor of phenylephrine were seen in 4 of the 8 studies (P <or= 0.05). Phenylephrine 10 mg was significantly more effective than placebo at the primary time points and at 90 minutes after dosing in the meta-analyses using both the fixed-effects and random-effects models (P <or= 0.05). At 45, 120, and 180 minutes after dosing, phenylephrine 10 mg was also significantly more effective than placebo in the fixed-effects model (P <or= 0.05). Between 30 and 90 minutes after dosing, percent reductions from baseline in NAR ranged from 6.0 percentage points higher with phenylephrine than with placebo (at 30 and 45 minutes after dosing) to 16.6 percentage points higher (at 60 minutes after dosing). From 60 to 180 minutes after dosing, the percent reductions from baseline were generally >or=20% with phenylephrine. These meta-analyses of 7 crossover studies and the reanalysis of a parallel-group study support the effectiveness of a single oral dose of phenylephrine 10 mg as a decongestant in adults with acute nasal congestion associated with the common cold.