Chronotherapy of asthma with inhaled steroids: the effect of dosage timing on drug efficacy.

BACKGROUND

Studies in asthma with systemic corticosteroids given at 3:00 PM have shown a superior therapeutic benefit compared with dosing at other time points.

OBJECTIVE

The study was designed to compare beneficial and systemic effects of 800 micrograms of inhaled triamcinolone once daily at 3:00 PM (QD group) versus 200 micrograms conventional four times a day dosing (QID group).

METHODS

Efficacy outcome measures included forced expiratory volume in 1 second (FEV1), peak expiratory flow rates, bronchial responsiveness, and use of beta-agonist. Systemic effects were blood eosinophil and cortisol levels, 24-hour urinary cortisol, and evaluation for oral candidiasis and dysphonia.

RESULTS

The baseline FEV1 was comparable in the two groups: QD = 67% +/- 2% and QID = 66% +/- 2% of predicted value. After 4 weeks of treatment, FEV1 increased similarly in the QD group to 77% +/- 4% and in the QID group to 74% +/- 4% of predicted value. Likewise, the improvement in morning and evening peak expiratory flow rates was not significantly different between the groups. Both QD and QID groups experienced comparable daily decrements in beta-agonist use. The systemic responses to the two regimens as assessed by eosinophil count, morning serum cortisol, and 24-hour urinary cortisol were also comparable.

CONCLUSIONS

The single daily administration of inhaled triamcinolone at 3:00 PM has no increased systemic effects and produces similar improvement in efficacy variables. A dosing strategy based on once daily dosing should increase compliance of inhaled steroid use in the clinical setting.