Decreased rhinovirus shedding after intranasal oxymetazoline application in adults with induced colds compared with intranasal saline.

BACKGROUND: Intranasal oxymetazoline (OMZ) is used as a decongestant during common colds. Recently, intracellular adhesion molecule (ICAM) 1 receptor expression in vitro has been shown to be diminished by OMZ. ICAM-1 is the major receptor used by rhinovirus to gain entry to human cells. The objective of this study was to assess the effect of OMZ on geometric mean titer of rhinovirus in nasal lavage fluid after rhinovirus inoculation. METHODS: Volunteers with antibody titers of ≤1:4 to rhinovirus type 39 were enrolled in a randomized, reference-controlled, double-blind study. Beginning 3 hours after intranasal challenge with 100-300 tissue culture infectious dose (TCID)50 of virus, subjects received active 0.05% OMZ (45 µL containing 22.5 µg of OMZ hydrochloride in citrate buffer) or reference control (physiological saline solution [PSS]) three times daily for 5 days. Rhinovirus was detected in fibroblast cultures. RESULTS: Geometric mean viral titer (log10) in 34 rhinovirus-infected subjects receiving OMZ was 1.49 on day 2 compared with 2.24 in the 38 infected subjects receiving PSS (p = 0.04). On day 3, the mean titers were 1.45 and 2.08, respectively. Median length of viral shedding was 3.3 days (OMZ) and 3.4 (PSS). Duration of clinical illness was 6.1 days in both groups. CONCLUSION: Topical OMZ decreased viral titer on day 2 during experimental rhinovirus infection in normal volunteers.

Alpha-adrenoceptor agonistic activity of oxymetazoline and xylometazoline.

Oxymetazoline and xylometazoline are both used as nasal mucosa decongesting α-adrenoceptor agonists during a common cold. However, it is largely unknown which of the six α-adrenoceptor subtypes are actually present in human nasal mucosa, which are activated by the two alpha-adrenoceptor agonists and to what extent. Therefore, mRNA expression in human nasal mucosa of the six α-adrenoceptor subtypes was studied. Furthermore, the affinity and potency of the imidazolines oxymetazoline and xylometazoline at these α-adrenoceptor subtypes were examined in transfected HEK293 cells. The rank order of mRNA levels of α-adrenoceptor subtypes in human nasal mucosa was: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) >> α(1B) . Oxymetazoline and xylometazoline exhibited in radioligand competition studies higher affinities than the catecholamines adrenaline and noradrenaline at most α-adrenoceptor subtypes. Compared to xylometazoline, oxymetazoline exhibited a significantly higher affinity at α(1A) - but a lower affinity at α(2B) -adrenoceptors. In functional studies in which adrenoceptor-mediated Ca(2+) signals were measured, both, oxymetazoline and xylometazoline behaved at α(2B) -adrenoceptors as full agonists but oxymetazoline was significantly more potent than xylometazoline. Furthermore, oxymetazoline was also a partial agonist at α(1A) -adrenoceptors; however, its potency was relatively low and it was much lower than its affinity. The higher potency at α(2B) -adrenoceptors, i.e. at receptors highly expressed at the mRNA level in human nasal mucosa, could eventually explain why in nasal decongestants oxymetazoline can be used in lower concentrations than xylometazoline.

Anti-rhinovirus-specific activity of the alpha-sympathomimetic oxymetazoline.

Oxymetazoline (CAS 2315-02-8, OMZ, Nasivin) known as the active ingredient in nose drops and sprays demonstrates excellent efficacy in the treatment of rhinitis symptoms that are mainly caused by Rhinovirus infections. To elucidate possible modes of action, the antiviral activity of OMZ was studied in vitro on human pathogenic viruses. No in vitro effects were detected against enveloped RNA viruses, Parainfluenza Virus and Respiratory Syncytial Virus and against Adenovirus, a non-enveloped DNA-virus. In contrast, OMZ showed a specific inhibition of Human Rhinovirus (HRV). Analysis of production of HRV-14 and HRV-39 after treatment of infected HeLa cells using plaque-reduction assay and virus titration showed a strong dose-dependent antiviral activity of OMZ. Additional data demonstrated that OMZ did also directly affect HRV-14 infectivity in a dose-dependent manner. Analysis of a cell-protective effect of OMZ showed that pre-treatment of HeLa cells decreased virus adsorption as well as virus replication. Furthermore, OMZ induced a down-regulation of ICAM-1 expression on Tumor Necrosis Factor-alpha (TNF-alpha)-stimulated HeLa cells and human umbilical vein endothelial cells. Taken together, these results show that OMZ besides its vasoconstrictive action also possesses potent antiviral and anti-inflammatory activities. Therefore, OMZ does not only reduce rhinitis symptoms but additionally offers a causal therapeutic approach.