Inhaled fluticasone propionate. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in asthma.

Fluticasone propionate is an androstane carbothioate glucocorticosteroid with almost twice the topical anti-inflammatory potency of beclomethasone dipropionate. Importantly, it is not appreciably absorbed from the gastrointestinal tract. However, the fraction of active drug absorbed from the lungs after inhalation, and therefore total systemic availability, has yet to be determined. Inhaled fluticasone propionate administered at dosages of 1500 micrograms/day for 1 year or 2000 micrograms/day for 6 weeks did not cause clinically significant pituitary-adrenal suppression. Preliminary data from 2 published trials also indicate no significant effect on growth in children. However, wider clinical experience is needed to clarify the effects of long term administration on pituitary-adrenal function, bone metabolism and attainment of adult height in children. In clinical studies, inhaled fluticasone propionate was at least as effective as beclomethasone dipropionate or budesonide when administered at half the dosage of the comparators in patients with mild to moderate or severe asthma. Limited data suggest that fluticasone propionate also has considerable potential in the management of childhood asthma. In trials of up to 1 year in duration, fluticasone propionate appeared to be well tolerated by both adults and children. Whether an improved tolerability profile compared with other corticosteroids is a major clinical benefit of the extremely low oral bioavailability of inhaled fluticasone propionate requires confirmation. Nevertheless, on the basis of available data from initial clinical trials of mostly limited duration, inhaled fluticasone propionate offers an effective treatment option for the management of asthma, with the potential of an enhanced safety profile.