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.

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. 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.

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: Clinical Therapeutics. 2007;29(6):P1057-1070.