12.1 Mechanism of Action This product contains both fluticasone propionate and salmeterol. The mechanisms of action described below for the individual components apply to this combination product. These drugs represent 2 different classes of medications (a synthetic corticosteroid and a LABA) that have different effects on clinical, physiologic, and inflammatory indices. Fluticasone Propionate : Fluticasone propionate is a synthetic trifluorinated corticosteroid with anti-inflammatory activity. Fluticasone propionate has been shown in vitro to exhibit a binding affinity for the human glucocorticoid receptor that is 18 times that of dexamethasone, almost twice that of beclomethasone-17-monopropionate (BMP), the active metabolite of beclomethasone dipropionate, and over 3 times that of budesonide. Data from the McKenzie vasoconstrictor assay in humans are consistent with these results. The clinical significance of these findings is unknown. Inflammation is an important component in the pathogenesis of asthma. Corticosteroids have been shown to have a wide range of actions on multiple cell types (e.g., mast cells, eosinophils, neutrophils, macrophages, and lymphocytes) and mediators (e.g., histamine, eicosanoids, leukotrienes, and cytokines) involved in inflammation. These anti-inflammatory actions of corticosteroids contribute to their efficacy in the treatment of asthma. Salmeterol : Salmeterol is a selective LABA. In vitro studies show salmeterol to be at least 50 times more selective for beta 2 ‑adrenoceptors than albuterol. Although beta 2 ‑adrenoceptors are the predominant adrenergic receptors in bronchial smooth muscle and beta 1 ‑adrenoceptors are the predominant receptors in the heart, there are also beta 2 ‑adrenoceptors in the human heart comprising 10% to 50% of the total beta‑adrenoceptors. The precise function of these receptors has not been established, but their presence raises the possibility that even selective beta 2 ‑agonists may have ca... [See full FDA label]

12.3 Pharmacokinetics Absorption Fluticasone Propionate: Fluticasone Propionate/Salmeterol MDPI acts locally in the lung; therefore, plasma levels may not predict therapeutic effect. Trials using oral dosing of labeled and unlabeled drug have demonstrated that the oral systemic bioavailability of fluticasone propionate was negligible (<1%), primarily due to incomplete absorption and presystemic metabolism in the gut and liver. In contrast, the majority of the fluticasone propionate delivered to the lung was systemically absorbed. After administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI to patients aged 12 years and older with persistent asthma in a clinical trial, the mean C max value of fluticasone propionate was 66 pg/mL with a median t max value of approximately 2 hours. Salmeterol: After administration of 232 mcg/14 mcg Fluticasone Propionate/Salmeterol MDPI to patients aged 12 years and older with persistent asthma, the mean C max values of salmeterol was 60 pg/mL. The median t max was 5 minutes. Distribution Fluticasone Propionate: Following intravenous administration, the initial disposition phase for fluticasone propionate was rapid and consistent with its high lipid solubility and tissue binding. The volume of distribution averaged

4.2 L/kg. The percentage of fluticasone propionate bound to human plasma proteins averages 99%. Fluticasone propionate is weakly and reversibly bound to erythrocytes and is not significantly bound to human transcortin. Salmeterol: Volume of distribution data are not available for salmeterol. The percentage of salmeterol bound to human plasma proteins averages 96% in vitro over the concentration range of 8 to 7,722 ng of salmeterol base per milliliter, much higher concentrations than those achieved following therapeutic doses of salmeterol. Elimination Fluticasone Propionate: Following intravenous dosing, fluticasone propionate showed polyexponential kinetics and had a terminal elimination half-life of approxi... [See full FDA label]