Does Phenylephrine Really Control Allergic Rhinitis Symptoms?

Allergic rhinitis is a condition that keeps noses and pharmacists running.

During peak allergy seasons, patients bombard pharmacists with questions about OTC relief because their symptoms diminish quality of life, interfere with sleep, limit activities, cause work and school absences, create moodiness, and decrease concentration.

Treatment with decongestants and antihistamines typically curbs symptoms.

Given the more restricted access to pseudoephedrine because of its potential for abuse, OTC phenylephrine hydrochloride is a common and frequent substitute. It may be more convenient at first, but does it really control allergic rhinitis symptoms?

In 2007, the FDA recommended further study of phenylephrine hydrochloride to assess its efficacy and safety for allergic rhinitis. This action came after a citizen petition was filed.

In January 2016, The Annals of Allergy, Asthma, and Immunology published a study that showed phenylephrine hydrochloride tablets were no more effective than placebo.

Phenylephrine hydrochloride has been plagued with poor bioavailability. When the 10 mg immediate-release tablets were studied, their peak effect was shown to dramatically diminish after 1.5 hours. The idea to formulate a modified-release tablet addressed patient adherence and bioavailability issues.

One randomized, double-blinded, placebo control trial evaluated phenylephrine hydrochloride 30 mg modified-release tablets in patients with nasal congestion. This formulation was expected to provide constant phenylephrine hydrochloride levels for 12 hours. For 7 days, the researchers followed 575 participants taking either placebo or phenylephrine twice daily, 12 hours apart.

The investigators assessed difference from baseline over the entire course of treatment based on patients' use of a standardized tool called the reflective daily nasal score. Patients recorded their scores in a diary, and the score averaged patients’ morning and nighttime assessments of nasal congestion.

No significant difference in congestion was noted between the 288 phenylephrine hydrochloride-treated patients and 287 placebo patients. Safety profiles were also similar.

The modified-release formulation didn’t seem to be equivalent or more effective than the immediate-release formulations.

The study recommended that guidelines should be altered to steer patients toward more effective treatments for allergic rhinitis and concluded that phenylephrine hydrochloride is no better than placebo.

Allergic rhinitis, also known as hay fever, affects more than 50 million Americans.