No metabolites of fluticasone propionate were detected in an in vitro study of radiolabeled fluticasone propionate incubated in a human skin homogenate. The total blood clearance of systemically absorbed fluticasone propionate averages 1,093 mL/min (range, 618 to 1,702 mL/min) after a 1-mg intravenous dose, with renal clearance accounting for less than % of the total. Fluticasone propionate is metabolized in the liver by cytochrome P450 3A4-mediated hydrolysis of the 5- fluoromethyl carbothioate grouping. This transformation occurs in 1 metabolic step to produce the inactive17-ÃŸ-carboxylic acid metabolite, the only known metabolite detected in man. This metabolite has approximately 2,000 times less affinity than the parent drug for the glucocorticoid receptor of human lung cytosol in vitro and negligible pharmacological activity in animal studies. Other metabolites detected in vitro using cultured human hepatoma cells have not been detected in man.
A person who has adrenal insufficiency should always carry identification stating his or her condition in case of an emergency. The card should alert emergency personnel about the need to inject 100 mg of cortisol if its bearer is found severely injured or unable to answer questions. The card should also include the doctors name and telephone number and the name and telephone number of the nearest relative to be notified. When traveling, it is important to have a needle, syringe, and an injectable form of cortisol for emergencies. A person with Addisons disease also should know how to increase medication during periods of stress or mild upper respiratory infections. Immediate medical attention is needed when severe infections or vomiting or diarrhea occur. These conditions can precipitate an addisonian crisis. A patient who is vomiting may require injections of hydrocortisone.
Patients requiring oral corticosteroids should be weaned slowly from systemic corticosteroid use after transferring to ADVAIR HFA. Prednisone reduction can be accomplished by reducing the daily prednisone dose by mg on a weekly basis during therapy with ADVAIR HFA. Lung function (mean forced expiratory volume in 1 second [FEV 1 ] or morning peak expiratory flow [AM PEF]), beta-agonist use, and asthma symptoms should be carefully monitored during withdrawal of oral corticosteroids. In addition, patients should be observed for signs and symptoms of adrenal insufficiency, such as fatigue, lassitude, weakness, nausea and vomiting, and hypotension.