The study used three sources to recognize 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 with the help of keyword phenylephrine nasal. The studies included had a single-dose, randomized, placebo-controlled design, which consisted of an orally administered agent in the form of phenylephrine 10 mg as a sole active ingredient. The patients included had acute nasal congestion due to the common cold. These were assessed for nasal airway resistance (NAR) as the efficacy end point; and in addition, therapeutic potential of phenylephrine 10 mg was contrasted against placebo. Re-assessment of individual studies and fixed-effects and random-effects meta-analyses were conducted. Statistical significance at 30 and 60 minutes after dosing, the primary time points and a ≥20% reduction in NAR from baseline were suggestive of a clinically relevant difference.

Oral phenylephrine, a non-prescription drug is considered safe and effective by the US Food and Drug Administration (FDA), however, its efficacy as a nasal decongestant is still controversial. The current study analysed available data on the effectiveness of oral phenylephrine 10 mg as a nasal decongestant.

The outcome revealed that 15 potentially relevant studies were recognized, among which 8 met the inclusion criteria. Re-evaluation of data from 7 crossover studies including a total of 113 subjects was done and then pooled for meta-analysis; results from the initial phase of the eighth study, a parallel-group trial including 50 subjects, were used in the re-assessment of individual studies but not in the meta-analyses. Remarkable difference in relation of phenylephrine were seen in 4 of the 8 studies. Moreover, phenylephrine 10 mg was more potent in comparison to 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., Phenylephrine was also more efficient than placebo in the fixed-effects model, at 45, 120, and 180 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). This percent reductions from baseline were ≥20% with phenylephrine from 60 to 180 minutes after dosing.

Thus, the findings of these meta-analyses of 7 crossover studies and the reanalysis of a parallel-group study established the efficiency of phenylephrine as a decongestant in individuals with acute nasal congestion related with the common cold.

Source: Kollar C, Schneider MH, Waksman J, Krusinska E. 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. Clinical Therapeutics. 2007;29(6):P1057-1070.