Pharmacology Versus Convenience: A Benefit/Risk Analysis of Regular Maintenance Versus Infrequent or As-Needed Inhaled Corticosteroid Use in Mild Asthma.

Abstract

IntroductionThis study compared the bronchoprotective and benefit/risk profiles of various inhaled corticosteroid (ICS) dosing regimens in mild asthma.MethodsA pharmacokinetic/pharmacodynamic model was developed and validated describing the relationship between ICS dose and time-course for airway bronchoprotection, [provocative concentration of adenosine monophosphate (AMP) causing ≥ 20% decline in forced expiratory volume in 1 s (FEV1) (AMP PC20)], for fluticasone furoate (FF), fluticasone propionate (FP) and budesonide (BUD). For regular ICS maintenance therapy (100% and 50% adherence) and infrequent or as-needed use (dosing 3–4 times per week), treatment effectiveness was expressed as percent time during 28 days when bronchoprotection exceeded either the threshold for a treatment-related bronchoprotective effect (AMP PC20 ≥ 0.25 doubling dose) or the threshold for a clinically significant bronchoprotective effect (AMP PC20 ≥ 1.0 doubling dose). This value was divided by the total ICS dose administered expressed in prednisolone equivalents to give a therapeutic index (TI).ResultsThe model-predicted time course of ICS-induced bronchoprotection with regular daily maintenance dosing and 100% adherence showed that all ICS at the highest recommended doses for mild asthma exceeded the threshold for clinically significant bronchoprotective effect for all or most of the 28-day dosing period, mean (90% CI); 100% (96.1–100), 99.9% (8.0–100) and 100% (58.2–100) with TI values of 16.9, 6.6 and 5.4 for FF 100 µg OD, FP 200 µg BID and BUD 200 µg BID, respectively. For simulated poor adherence (50%) to regular daily maintenance therapy, corresponding mean (90% CI) values were; 75.7% (39.4–89.1), 52.3% (0.7–69.2) and 51.3% (28.6–58.3) with TI values of 25.7, 6.9 and 5.6. For simulated infrequent/as needed use the corresponding values were; 77.0% (37.6–87.0), 25.5% (0.0–38.0) and 26.2% (14.3–31.5) with TI values of 26.1, 6.7 and 5.7. For all regimen/scenarios, FF had the most sustained efficacy and favourable TI followed by FP and BUD.ConclusionsAt doses recommended for mild asthma, all ICS regimens provide sustained bronchoprotective efficacy when dosed regularly with high adherence. With poor adherence or use 3–4 times per week (infrequent/as needed), longer-acting ICS molecules will more likely provide sustained protection and a better TI versus shorter duration of action molecules (FF > FP ≥ BUD). These data highlight the benefits of using ICS as regular daily maintenance dosing in mild asthma and the potential risks of under-treatment with ICS (which may occur with ICS/formoterol as-needed approach in mild persistent asthma) associated with reduced levels of bronchoprotection.