There are no data available on the effects of acute or chronic overdosage with NASONEX Nasal Spray 50 mcg. Because of low systemic bioavailability, and an absence of acute drug-related systemic findings in clinical studies, overdose is unlikely to require any therapy other than observation. Intranasal administration of 1600 mcg (4 times the recommended dose of NASONEX Nasal Spray 50 mcg for the treatment of nasal polyps in patients 18 years of age and older) daily for 29 days, to healthy human volunteers, showed no increased incidence of adverse events. Single intranasal doses up to 4000 mcg and oral inhalation doses up to 8000 mcg have been studied in human volunteers with no adverse effects reported. Chronic over dosage with any corticosteroid may result in signs or symptoms of hypercorticism [see Warnings and Precautions]. Acute overdosage with this dosage form is unlikely since one bottle of NASONEX Nasal Spray 50 mcg contains approximately 8500 mcg of mometasone furoate.
It is likely that much of the mechanism for the anti-allergic and anti-inflammatory effects of mometasone furoate lies in its ability to inhibit the release of mediators of allergic reactions. Mometasone furoate significantly inhibits the release of leukotrienes from leucocytes of allergic patients. In cell culture, mometasone furoate demonstrated high potency in inhibition of synthesis and release of IL-1, IL-5, IL-6 and TNFα; it is also a potent inhibitor of leukotriene production. In addition, it is an extremely potent inhibitor of the production of the Th2 cytokines, IL-4 and IL-5, from human CD4+ T-cells.