Why is fluticasone more frequently associated with adrenal suppression than other inhaled corticosteroids for the treatment of asthma?

Inhaled corticosteroids are highly effective in controlling asthma but have been associated with adrenal suppression.  Adrenal insufficiency can occur chronically from systemic absorption of the corticosteroid resulting in feedback suppression of endogenous glucocorticoid production. Suppression can also occur acutely if the patient abruptly discontinues treatment rather than gradually stepping down the corticosteroid dose. The suppressed adrenal system is then unable to respond adequately to stressful stimuli such as trauma and infection. Signs and symptoms of adrenal suppression can include anorexia, abdominal pain, weight loss, fatigue, headache, nausea, vomiting, decreased level of consciousness, hypoglycaemia and seizures. 

Although adrenal suppression can occur with any inhaled corticosteroid, fluticasone, in particular, has  been most frequently associated with adrenal insufficiency.  This is likely due to the greater potency of fluticasone, which results in a greater risk of prescription of higher-than-licensed doses of fluticasone (1). In particular, children, the elderly and other patients requiring dose adjustment may be at increased risk.  It is also important for prescribers to remember that “beyond a certain limit, increasing the dose of inhaled corticosteroids offers minimal benefit but increases the risk of systemic adverse effects” (1). 

Reference:
(1) WHO Drug Information Vol. 17, No. 4, 2003, Safety and Efficacy Issues, Fluticasone and adrenal suppression [accessed 4 Feb 2017]