A reappraisal of the clinical efficacy of nebulized flunisolide in pediatric asthma: The Italian experience

Flunisolide (FLU) is a synthetic corticosteroid with potent topical anti-inflammatory activity. Its oral bioavailability is poor (6.7%). After gastrointestinal and lung absorption, the drug undergoes rapid and extensive first-pass metabolism by the liver to an inactive 6-hydroxylated metabolite. Plasma half-life is estimated to be 3.9 to 4.6 hours. FLU has a low volume of distribution at steady state and a short terminal half-life after inhalation (96 L and 1.6 hour, respectively). FLU, like budesonide, has a short pulmonary residence time and it is hypothesized that it may undergo esterification in the cell due to the presence of a free hydroxyl group at C21. Nebulization may offer important advantages over other inhalation methods. Nebulizers allow drug delivery in very young children through passive inhalation, depending less on patient coordination and cooperation. Comparative studies indicate that FLU is nebulized to a better advantage than beclomethasone dipropionate and budesonide. This is attributed to its elevated water solubility. The aim of this article is to outline the factors that influence drug nebulization and the pharmacokinetics–pharmacodynamics of FLU compared to other inhaled corticosteroids. In addition, we report a series of clinical data regarding the efficacy of nebulized FLU with focus on the Italian experience. Overall, the physicochemical characteristics and pharmacokinetic profile of FLU favor its use for nebulization. Clinical data indicate that nebulized FLU is effective in asthma treatment in infants and children. Side effects were not reported at the commonly used doses.