The degree of systemic exposure after inhalation of corticosteroids is of great clinical concern. For optimum outcome, the pulmonary deposition should be sufficiently high to produce the desired anti‐inflammatory effect in the lungs, whereas the plasma concentrations due to the absorption of the corticosteroid from the lung and the gut should be minimal. Recently, it has been reported that inhaled mometasone furoate has a systemic bioavailability of less than 1%, which is much lower than other corticosteroids currently available. However, critical evaluation of the study methodology and results does not support this finding. A major shortfall of the study was an insufficient analytical sensitivity, resulting in a calculated average plasma concentration profile that was entirely below the limit of quantification. These numbers were generated by replacing all concentrations below the limit of quantification by zero and then calculating an average value. This procedure can lead to erroneous results and misinterpretation. Furthermore, the potential contribution of active metabolites needs to be adequately addressed in comparisons of inhaled corticosteroids. Reliable estimates of systemic drug exposure are critical in evaluating the real safety profiles and therapeutic index for inhaled corticosteroids that are effective in treating chronic asthma.
We thank Dr Garcia Arieta for his interest and comments on our article.The use of in vitro data alone is a feature of the European guidance [1]. Dr Garcia Arieta's comment that this route of approv...
Introduction In patients with chronic obstructive pulmonary disease (COPD), dual bronchodilator (long-acting muscarinic antagonist (LAMA)/long-acting beta2-agonist (LABA)) and triple therapy (inhaled corticosteroid (ICS)/LAMA/LABA) reduce risk of exacerbations and lung function decline in short-mid-term, but their long-term impact is unknown. This modelling study explores long-term impact of these therapies on lung function decline, quality of life (QoL) and all-cause mortality. Methods This modelling approach used a longitudinal non-parametric superposition model using published data regarding exacerbations, QoL (assessed by St. George's Respiratory Questionnaire (SGRQ)), and mortality. The model simulated disease progression from 40 to 75 years of age and assessed the impact of initiating dual bronchodilator at age 45 years (“LAMA/LABA only” group) and escalation to triple therapy at age 50 years (“Escalation to triple” group) on forced expiratory volume in 1 s (FEV 1 ) decline, QoL, and mortality. Results Model simulation predicted that by 75 years of age: “LAMA/LABA only” preserves 159.1 mL of FEV 1 versus no treatment, “Escalation to triple” preserves an additional 376.5 mL and 217.3 mL of FEV 1 versus no pharmacotherapy and “LAMA/LABA only”, respectively. In “LAMA/LABA only”, SGRQ score reduces (−3.2) versus no treatment, which further reduces to −7.5 therapy in “Escalation to triple”. In “LAMA/LABA only”, mortality reduces by 5.4% by 75 years versus no treatment, while the “Escalation to triple” shows further decrease in mortality by 12.0%. Conclusion Early pharmacotherapy initiation and escalation from dual bronchodilator to triple therapy could slow disease progression by preserving lung function and improving QoL and survival in patients with COPD.
Abstract The study aim was to investigate the pharmacokinetics of single high doses and repeated therapeutic doses of fluticasone furoate (FF) and batefenterol (BAT; a bifunctional muscarinic antagonist and β 2 ‐agonist) administered in combination (BAT/FF) or as monotherapy. In this open‐label, 6‐period, crossover study of 48 subjects, the treatment sequences were (1) single high‐dose BAT/FF 900/300 μg followed by repeated therapeutic doses of BAT/FF 300/100 μg (once daily for 7 days); (2) single high‐dose BAT 900 μg administered concurrently with FF 300 μg; (3) single high‐dose BAT 900 μg followed by repeated therapeutic‐dose BAT 300 μg; (4) single high‐dose FF 300 μg followed by repeated therapeutic‐dose FF 100 μg; (5) single high‐dose FF 300 μg (magnesium stearate); and (6) single high‐dose FF/vilanterol 300/75 μg. Plasma FF area under the plasma drug concentration‐time curve (AUC) was reduced after single high‐dose BAT/FF versus FF alone (ratio of geometric least squares means: 0.79; 90% confidence interval: 0.75‐0.83). After repeat dosing, FF AUC at the lower therapeutic dosage was similar for BAT/FF and FF (primary endpoint; AUC geometric least squares means: 1.03). Adverse events were minor, the most common being cough. These data support the feasibility of developing BAT/inhaled corticosteroid triple therapy in a single inhaler.
Glucocorticosteroids are a group of structurally related molecules that includes natural hormones and synthetic drugs with a wide range of anti-inflammatory potencies. For synthetic corticosteroid analogues it is commonly assumed that the therapeutic index cannot be improved by increasing their glucocorticoid receptor binding affinity. The validity of this assumption, particularly for inhaled corticosteroids, has not been fully explored. Inhaled corticosteroids exert their anti-inflammatory activity locally in the airways, and hence this can be dissociated from their potential to cause systemic adverse effects. The molecular structural features that increase glucocorticoid receptor binding affinity and selectivity drive topical anti-inflammatory activity. However, in addition, these structural modifications also result in physicochemical and pharmacokinetic changes that can enhance targeting to the airways and reduce systemic exposure. As a consequence, potency and therapeutic index can be correlated. However, this consideration is not reflected in asthma treatment guidelines that classify inhaled corticosteroid formulations as low-, mid- and high dose, and imbed a simple dose equivalence approach where potency is not considered to affect the therapeutic index. This article describes the relationship between potency and therapeutic index, and concludes that higher potency can potentially improve the therapeutic index. Therefore, both efficacy and safety should be considered when classifying inhaled corticosteroid regimens in terms of dose equivalence. The historical approach to dose equivalence in asthma treatment guidelines is not appropriate for the wider range of molecules, potencies and device/formulations now available. A more robust method is needed that incorporates pharmacological principles.
In the session on Pharmacodynamic studies to demonstrate efficacy and safety, presentations were made on methods of evaluating airway deposition of inhaled corticosteroids and bronchodilators, and systemic exposure indirectly using pharmacodynamic study designs. For inhaled corticosteroids, limitations of measuring exhaled nitric oxide and airway responsiveness to adenosine for anti- inflammatory effects were identified, whilst measurement of 18-h area under the cortisol concentra- tion-time curve was recommended for determining equivalent systemic exposure. For bronchodilators, methacholine challenge was recommended as the most sensitive method of determining the relative amount of β-agonist or anti-muscarinic agent delivered to the airways. Whilst some agencies, such as the Food and Drug Administration (FDA), do not require measuring systemic effects when pharmacokinetic measurements are feasible, the European Medicines Agency requires measurement of heart rate and serum potassium, and some require serial electrocardiograms when bioequivalence is not established by pharmacokinetic (PK) studies. The Panel Discussion focused on whether PK would be the most sensitive marker of bioequivalence. Furthermore, there was much discussion about the FDA draft guidance for generic fluticasone propionate/salmeterol. The opinion was expressed that the study design is not capable of detecting a non-equivalent product and would require an unfeasibly large sample size.
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