Phenylephrine hydrochloride modified-release tablets for nasal congestion: a randomized, placebo-controlled trial in allergic rhinitis patients

The Use and Efficacy of Oral Phenylephrine Versus Placebo Treating Nasal Congestion Over the Years on Adults: A Systematic Review

Nasal congestion is a common issue stemming from various factors such as allergies and anatomical variations. Allergic rhinitis frequently leads to nasal congestion. The pathophysiology involves inflammation, swelling, and mucus production in the nasal mucosa. Multiple treatments are available, including oral phenylephrine, an over-the-counter or prescription option. However, the effectiveness and safety of phenylephrine have been subjects of debate. This systematic review aims to provide an updated perspective on the efficacy of oral phenylephrine versus placebo in addressing nasal congestion in adults. We conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a systematic review involving searches on PubMed, Cochrane, and Scopus databases. Inclusion/exclusion criteria were defined to identify high-quality studies. The focus was on randomized controlled trials (RCTs) and case-control studies published in English between 1998 and 2023, involving adult populations. The interventions compared oral phenylephrine with placebo or standard care, with outcomes centering on changes in nasal congestion symptoms and nasal airway resistance. We identified four articles that met the criteria. These studies exhibited varied designs and populations. The findings consistently indicated that phenylephrine was not more effective than a placebo in relieving nasal congestion. This systematic review demonstrates that oral phenylephrine did not offer substantial relief from nasal congestion compared to a placebo in adults. The studies featured diverse designs, yet the prevailing conclusion was that phenylephrine's efficacy was limited. Safety assessments showed no life-threatening adverse events, with common side effects including headaches and mild discomfort. In summary, this systematic review indicates that oral phenylephrine is not significantly more effective than a placebo in alleviating nasal congestion in adults. Clinicians should explore alternative treatment options, considering the review's limitations. Additional research may be needed to clarify the role of oral phenylephrine in managing nasal congestion.

Why Is Oral Phenylephrine on the Market After Compelling Evidence of Its Ineffectiveness as a Decongestant?

Ineffective over-the-counter (OTC) drugs should be removed from the US market. Despite solid research showing that oral phenylephrine is ineffective as a decongestant, the US Food and Drug Administration has failed to respond to a 2015 citizen's petition to remove it from the OTC nasal decongestant monograph. Other examples of scientifically proven ineffective OTC medications include guaifenesin as an expectorant, dextromethorphan as a cough suppressant, and chlorpheniramine for cold symptoms.

15-hydroxy eicosadienoic acid is an exacerbating factor for nasal congestion in mice

Allergic rhinitis (AR) is one of the most common allergic inflammatory diseases worldwide. In AR, increased blood flow and vascular permeability in nasal mucosa cause rhinorrhea and nasal congestion. We investigated the role of an 11Z,14Z-eicosadienoic acid-derived metabolite, 15-hydroxy-11Z,13Z-eicosadienoic acid (15-HEDE), in functional changes in vasculature and nasal congestion in AR. Repeated intranasal administration of Ovalbumin (OVA) caused AR symptoms, such as sneezing and nasal congestion, in mice. OVA administration increased the level of 15-HEDE in nasal lavage fluid, which reached approximately 0.6 ng/ml after ten OVA treatments. Upon measuring vascular contraction, treatment with 0.1-3 μM 15-HEDE did not cause contraction in mouse aortae, while it dilated aortae that were pre-contracted by thromboxane receptor stimulation. Pretreatment with the voltage-gated K⁺ (K_V ) channel inhibitor 4-aminopyridine significantly inhibited the 15-HEDE-induced vascular relaxation. Intravital imaging showed that administration of 1 μg 15-HEDE dilated blood vessels, and Mile's assay demonstrated that this administration also caused dye leakage, indicating vascular hyperpermeability in mouse ears. Computed tomography scanning and morphological study revealed that administration of 3 μg 15-HEDE narrowed nasal passages and thickened nasal mucosa in mice. Finally, we confirmed that treating mice with 3 μg 15-HEDE caused rhinitis symptoms, such as abdominal breathing, and reduced respiratory frequency, suggesting nasal congestion. 15-HEDE caused vasodilation by activating K_V channels and increased vascular permeability, which may lead to nasal congestion. Furthermore, 15-HEDE might be a new lipid mediator that exacerbates nasal congestion in AR.

Rhinitis 2020: A practice parameter update

This comprehensive practice parameter for allergic rhinitis (AR) and nonallergic rhinitis (NAR) provides updated guidance on diagnosis, assessment, selection of monotherapy and combination pharmacologic options, and allergen immunotherapy for AR. Newer information about local AR is reviewed. Cough is emphasized as a common symptom in both AR and NAR. Food allergy testing is not recommended in the routine evaluation of rhinitis. Intranasal corticosteroids (INCS) remain the preferred monotherapy for persistent AR, but additional studies support the additive benefit of combination treatment with INCS and intranasal antihistamines in both AR and NAR. Either intranasal antihistamines or INCS may be offered as first-line monotherapy for NAR. Montelukast should only be used for AR if there has been an inadequate response or intolerance to alternative therapies. Depot parenteral corticosteroids are not recommended for treatment of AR due to potential risks. While intranasal decongestants generally should be limited to short-term use to prevent rebound congestion, in limited circumstances, patients receiving regimens that include an INCS may be offered, in addition, an intranasal decongestant for up to 4 weeks. Neither acupuncture nor herbal products have adequate studies to support their use for AR. Oral decongestants should be avoided during the first trimester of pregnancy. Recommendations for use of subcutaneous and sublingual tablet allergen immunotherapy in AR are provided. Algorithms based on a combination of evidence and expert opinion are provided to guide in the selection of pharmacologic options for intermittent and persistent AR and NAR.