Impact of nasal congestion on intranasal rescue medication absorption and efficacy: A systematic review.

Background: It is critical for rescue medications to have rapid absorption and onset of action. Although intranasal formulations of rescue medications have advantages over other forms of administration, the impact of nasal congestion on drug absorption has been questioned. Objective: We aimed to determine if nasal congestion impacts the absorption and efficacy of intranasal rescue medications. Methods: A rescue medication is used as needed for the immediate treatment of an episodic medical event that requires urgent intervention. Systematic searches for 15 pre-identified intranasal rescue medications were conducted in PubMED/MEDLINE up to July 2, 2024. Eligible studies were controlled human studies that compared the absorption or efficacy of an identical dose of intranasal rescue medication administered with and without the presence of nasal congestion that was induced by allergen challenge or that was associated with a medical condition (e.g., allergic rhinitis). Results: The searches identified 160 articles; six studies, all open-label, were eligible for final inclusion. Two intranasal epinephrine studies showed increased maximum plasma concentrations after allergen-induced congestion; one of these epinephrine studies also showed a faster time to maximum plasma concentration. Three additional studies that evaluated epinephrine, glucagon, and fentanyl found no effect of congestion on absorption. In the sixth study, congestion had no effect on zolmitriptan efficacy. Conclusion: Available evidence indicates no negative impact of nasal congestion on the absorption of intranasal rescue medications. Congestion may actually increase absorption of some intranasal epinephrine formulations. The impact of congestion on intranasal medication absorption is likely dependent on each drug's properties, mode of action, and formulation.